This study used liquefied red mud (RM) sludge, an aluminum industry by-product, as a construction material. Accordingly, various methods were examined that used the fabricated liquefied red mud (LRM) as an admixture for concrete, and the mechanical properties of concrete were then evaluated according to the cement type and the amount of LRM. The LRM mixing methods (replacement and addition) were compared, and the slump and compressive strengths of concrete were evaluated for each method. To examine the mechanical properties according to the cement type and the amount of LRM, two types of cement (ordinary Portland cement and slag cement (SC)) were used, and 20 and 40 wt% LRM (with respect to the cement weight) were added. The mechanical properties of the stress–strain curve (SSC), compressive strength, peak strain, and elastic modulus were quantified. When the slump and compressive strength of concrete were considered based on the experimental results, the addition LRM mixing method was recommended as the appropriate method for LRM. As the addition of LRM increased, the mechanical properties of concrete degraded. However, when SC was used, the mechanical properties did not significantly change when different amounts of LRM were added (up to 20%). In addition, the SSC of LRM concrete could be approximated based on the use of the relationship of the compressive strength and peak strain according to the cement type and the amount of LRM.  Red mud (RM) is an aluminum industry by-product that is generated during the process of extraction of alumina from bauxite ore. It is discharged in a high-alkaline state at a pH in the range of 10–13 owing to the influence of caustic soda (NaOH) which is added in the process . In geneThe continuous industrial growth depends on the stable treatment of waste and the conservation of natural resources . Therefo2 emissions from cement production has been a major issue. Cement is one of the most important materials in the construction industry, and has been extensively used in many countries. The production of one ton of clinker is estimated to emit one ton of CO2 gas. Additionally, it has been reported that approximately 7% of global CO2 emissions is related to cement production [2 emissions is to decrease the use of cement. Industrial by-products, such as fly ash, ground granulated blast-furnace slag, and silica fume, have been used as admixtures for concrete. RM is an industrial by-product, and can be used as an admixture for cement-based materials, such as mortar and concrete [In the construction industry, the reduction of COconcrete ,9. Moreoconcrete ,11,12,13In many prior studies, the effects of RM on the fluidity, hardening properties , and durability (chloride penetration and whitening) of mortar and concrete have been experimentally evaluated ,16,17,18RM is discharged as sludge from the Bayer process with a moisture content of 50%. It is very difficult to manage constant moisture content because it is significantly affected by environmental conditions . TherefoTherefore, in this study, we fabricated liquefied red mud (LRM) to achieve the efficient quality control of RM and the omission of the energy-intensive drying process. In addition, the proper use of LRM as concrete admixture was examined to expand the use of RM as a building material. The mechanical properties of concrete mixed with LRM are presented based on the evaluation of the compressive strength, peak strain, elastic modulus, and stress–strain relationship of concrete according to the cement type and the amount of LRM.3, an average diameter of 4.31 μm, a moisture content of 50.2%, and a viscosity of 20,000 cPs. The main oxides contained in RM were SiO2, Al2O3, Fe2O3, CaO, MgO, Na2O, and K2O, while the content of SiO2, Al2O3, and Fe2O3, represented more than 80% of the total mass. LRM was fabricated with the use of water, RM sludge, a thickener, and an antifoamer. The RM sludge  obtained3. The average particle diameter was 3.15 μm and the viscosity was 7850 cPs. Ordinary Portland cement (OPC) and slag cement (SC) were used. 3, maximum size of 5 mm, water absorption of 1.01%, and a fineness modulus of 2.6, were used as fine aggregates. Granite with a density of 2.67 g/cm3, a maximum size of 20 mm and water absorption of 1.39% were used as the coarse aggregate.ck) was set as 35 and 15 MPa and SC was used. The slump was measured as a fresh property and the compressive strength as a hardened property.ck 25 MPa) regardless of the cement type. Regarding the LRM, 20% and 40% of the cement weight were added in the same manner as in the previous step. Regarding the mechanical properties, the stress–strain curve (SSC), compressive strength, elastic modulus, and peak strain, were evaluated. For the evaluation of the mechanical properties of LRM-added concrete as a function of the cement type, two types of cement, i.e., OPC and SC were used. The W/B ratio was set to 55% (fThe sand-aggregate (S/A) ratio was set at 50% for all the concrete specimens used in the experiment.2 per second, and the stress of each specimen was measured with a load cell. The deformation of each specimen under the compression load was evaluated using the average value of the displacement meters installed on both sides of the specimen. In the SSC obtained from the compression test  of the maximum stress, and the curves were almost linear. It is generally known that the cracks generated from the adhesion relationship between the cement paste and aggregate interface affected the curvature when stresses were less than 70% of the maximum stress . The shaMeanwhile, the curvature in the straight shape of the SSC occurred earlier as the LRM content increased. The onset of the curvature in the SSC is related to the cracks of mortar and their propagation. Previous studies have reported that the mixing of RM lowers the compressive strength of mortar. Therefore, different curvature starting points depend on the LRM application conditions, and are estimated to be affected by the strength development of mortar owing to the use of LRM.The ultimate stress of the concrete that used OPC showed a decreasing tendency with the addition of LRM, and the difference due to the LRM content was not large. However, in the case of the concrete that used SC, the ultimate stress did not significantly decrease for LRM contents up to 20%. After the maximum stress, the OPC concrete exhibited a short stress-reduction section, but the SC concrete exhibited brittle behavior as it ruptured when the maximum stress was developed or yielded a shorter stress-reduction section.2O, concrete containing RM includes high-alkali components. According to the previous literature [Meanwhile, the difference in the compressive strength of LRM-added concrete depended on the cement type and appeared to be affected by the increased alkali environment generated by the addition of RM. As the RM generally contains approximately 10% Naterature , alkali Therefore, to address the compressive strength reduction problem with concrete that uses RM, it is necessary to determine the appropriate cement type and RM substitution rate. In the range examined in this study, it was confirmed that more than 90% of the compressive strength of the plain type could be developed up to an age of 91 d if SC is used and if 20% LRM is added. In addition, based on the experimental results, the compressive strength development rate according to the LRM content can be expressed with Equations (1) and (2), depending on the cement type.Some codes have proposed the value of 0.002 as the peak strain of concrete in the case of uniaxial loading. However, the peak strain actually varies depending on the concrete mix, curing condition, shape and size of the specimen, loading rate, age, and experimental equipment ,30. Neveβ that determines the shape of the SSC exhibits no special tendency according to the cement type and LRM addition condition. The value of β was fixed to two. The variable fc was calculated with Equations (1) and (2), and the peak strain was estimated from the calculated fc using Equation (3). Based on the equation estimated by the LRM content, the approximate SSCs which were relatively similar to the experimentally obtained SSCs could be derived. Therefore, the approximate stress–strain relationship of LRM concrete can be used as a reference for various engineering areas.In this study, however, the descending phase could not be estimated because data could not be collected. In the SSC of the descending concrete, the descending phase after the ultimate stress is affected by the experimental equipment and is not recognized as a material property, but the nonlinear structural analysis of concrete structures, such as the seismic design, may require the descending phase section. Therefore, in future research, more detailed verification will be necessary based on the comparison between the experimental data of this section and the approximation formula.1. In this study, LRM was fabricated by mixing RM sludge, water, a thickener, and an antifoamer. When LRM was used as an admixture for concrete, there was no degradation in the fluidity of concrete that used conventional RM because the moisture reduction that affected the fluidity of the concrete mix could be prevented2. Concrete mixed with LRM exhibited problems associated with the increased W/B ratio and the decreased mechanical properties because the cement content decreased, and the water content increased compared to the designed mix. Therefore, the LRM addition method is recommended compared to the replacement method in which some cement was replaced with LRM based on considerations of changes in the fluidity and mechanical properties of concrete3. Owing to the influence of the high-alkaline environment generated by the addition of RM on the hydration products of cement, the mechanical properties of the LRM-added concrete varied depending on the cement type. Based on the experiment results, it is recommended that SC uses LRM as the concrete admixture and an LRM content of 20% with respect to the weight of the cement4. From the relationship between the compressive strength and peak strain according to the cement type and LRM content, the stress–strain relationship of the LRM concrete that can be used in engineering areas could be approximated. As the LRM content examined in this study had a limited range and the stress–strain relationship of concrete was affected by various mixing factors, it is necessary to use the results which had been verified experimentally given that they emulate accurately the required conditions when accurate stress–strain relationships are required


The article describes the possibility of using waste glass cullet as an alternative aggregate for the production of cement composites. Three concrete mixes based on Portland cement CEM I 42.5 R with different contents of recyclate were designed. Borosilicate glass cullet was introduced into the batch by reducing the content of natural aggregate by 0%, 2.5% and 7.5%. Apparent density, water absorption and compressive strength at elevated temperature were measured. The temperature distribution, in cubic samples, was followed by thermocouples. The elements were heated in a special furnace at the temperatures of 200 °C, 400 °C, 600 °C and 800 °C. The composite topography and phase composition were observed using X-ray energy scattering electron microscopy. The results show that the appropriate modification of the cement composite with 2.5% heat-resistant glass cullet improves both the thermal and mechanical properties. Compressive strength reaches an average value of 48.6 MPa after 28 days. The increase in temperature weakens the structure of the composite. It was found that the obtained cement composite has good physico–chemical properties. The research results are presented in the article. Glass is commonly used in the construction industry and in various industries branches. It is an inspiration in the search for new applications that require an interdisciplinary approach to the design and implementation processes .2), borax (source of glass forming component B2O3), sodium–potassium feldspar (source of Al2O3), sodium carbonate, limestone and others. Components of glass brands used in the construction sector comprise circa 70–72% SiO2, circa 15% Na2O, circa 10% CaO, as well as MgO, Al2O3 and other ingredients adopted to improve the properties of glass or to streamline the production process [Glass is distinguished by its transparency and is also a relatively hard material. Depending on its brand, it occupies the fifth or sixth position in the 10-level Mosh hardness scale. Its main weakness is its fragility. It is made of glass sand  ,7,8,9,10Glass used for the production of concrete needs to undergo a special processing procedure ,11. The Numerous researchers are looking for innovative solutions that would meet performance requirements and determine the inventive nature of the use of waste cullet. Recently conducted studies ,22,23,24Cullet is used as a substitute for cement, sand and coarse aggregate in concrete, and in addition may be used for stabilisation of natural soils or for the construction of roads and subgrades ,40. The When designing a cement composite, cullet may be introduced into concrete in the form of fibres, dust or grains. The addition of glass consisting of fibres ,48,49,50Replacing cement in the concrete mixture with crushed glass powder ,38,39 alWhen using glass cullet as a substitute for sand ,36,37,52Studies performed until now have proven that it is possible to adopt a solution based on replacement of coarse natural aggregate by waste aggregate. Studies took into consideration glass ,55,56,57A review of published research ,11 has sThe objective of the study was to assess the reuse of heat-resistant glass cullet obtained from damaged dishes. During pilot studies, apart from mechanical properties, also determined was the impact of fire temperatures on properties of the designed composite. The article presents the results of tests and analyses of the microstructure of the contact zone of the material.Pilot testing comprised the use of cement composite with diverse additions of recyclate C-0, C-2.5, C-7.5 . A part of the natural aggregate was replaced by borosilicate heatresistant glass cullet. When selecting recycled aggregate it was necessary to take into account first of all advantageous physical parameters and ecological aspects. The material was obtained primarily from broken glass of kitchen and laboratory dishes stocked on premises of the glass works in Wołomin  [2), boron trioxide (B2O3) or aluminium oxide (Al2O3). The isotropic material is characterised by higher resistance to thermal shock with a low thermal expansion coefficient. It retains a good thermal resistance in the working temperature range of −40 °C to 500 °C and withstands temperature difference in the range of 150–210 °C. A granulometric analysis of heat resistant glass cullet is presented in 3 (at 20 °C).Glass ingredients comprise among others silicon oxide  and gravel with a grading of 2/16 mm .All series of samples were produced based on Portland cement CEM I 42.5 R  and fly ash. The declared physical, chemical and mechanical properties of cement are presented in Mineral additive was used in the mixture that consisted of fly ash ProAsh cat. A  with pozzolanic properties. The fly ash fulfils criteria imposed by standard EN 450-1:2012 . ConcretConcrete mixtures were produced with the use of a plasticiser admixture that reduces the amount of water—Master Pozzolith 18 BVC . The concrete admixture belongs to a group of surfactants based on lignin sulphonates that are known to enhance the moisturising of cement grains by batched water and to assure better workability of the mixture. Physical and chemical properties of the admixture are presented in Potable water was used for production of the concrete mixture.Samples for testing were chosen in a random way. The composition of the source mixture is presented in For all the samples a constant water–cement ratio was assumed that equals 0.62. All mixtures were mixed and compacted thanks to the used chemical admixture 18 BVC  that consists of a superplasticiser based on lignin sulphonates. In addition, the aggregate composition and sand content (SC) of concrete mixtures were determined. The sand content of C-0, C-2.5 and C-7.5 amounted to 47%, 49%, 51%, respectively, in conformity with recommendations presented in EN 933-1: 2012 . The samThe technical properties of concrete are a set of all the physical, mechanical, rheological properties and their resistance to the impact of the environment. The article presents a few selected properties of the composite: absorbability, apparent density, compressive strength, deformability under the impact of temperature change , resistance to high temperature and microscopic structure testing.Optimum grading is found in the aggregate with the smallest number of cavities between grains, with containing possibly the coarsest aggregate grains. To determine the grading of glass cullet a sieve analysis was carried out. The recyclate was sifted through a set of sieves on a shaker, and then fractions remaining on the sieves and on the bottom were weighed. The test was performed pursuant to standard EN 933-1:2012 .The resistance to grinding was determined by measuring the fragmentation of the aggregate as a result of rolling together the aggregate with steel balls in a rotating drum. The Los Angeles (LA) factor corresponds to the mass of the analytical sample in fragmentation, expressed in %, which has passed through a 1.6 mm sieve after a complete drum rotation cycle. The test was carried out in accordance with the standard PN-EN 1097-2.Tests were conducted of the consistence of concrete mixtures according to the standard EN 12350-2:2009 . The mixBefore the commencement of proper tests, all the samples were weighed and dried to constant mass in the thermal chamber KC-100/200 , which was repeated until two consequent measurements were found not to differ one from the other by more than 0.1%, at the temperature of 105 °C ± 5 °C. All measurements of the mass were implemented to within an accuracy of 0.001 g. Test trials were conducted with a view to the determination of physical and mechanical properties. An absorbability test was implemented pursuant to the standard EN 206:2013 . ConstruMechanical tests were carried out in laboratory conditions at room temperature with the use of a hydraulic press. The production and curing of concrete samples designated for compressive strength tests were performed according to the standard PN-EN 12390-2 . The samc) was determined according to the standard PN-EN 12390-3 [c,cub150f and c,cub100f—compressive strength ascertained on cubic samples with edge lengths of 15 and 10 cm, respectively.The measurement unit was a Controls Advantest 9 press  including specialist software (Version 2.16-02/2010). Compressive strength is strictly correlated with the microstructure of hardened cement grout and the strength of aggregate and the aggregate–grout contact zone. Compressive strength  furnished with powered heating compartments. The stand has a dedicated programme ThermoPro that allows the programming of the thermal process. The temperature distribution in the analysed element was monitored using NiCr-Ni thermocouples that meet criteria defined by the standard .In order to identify phases based on a qualitative chemical analysis and crystalline structure, to obtain high resolution images of the forms of very small items and to obtain spatial differences in the chemical composition, scanning electron microscopy (SEM) was used. The observations were implemented using the FEG Quanta 250 microscope  equipped with an EDS system , based on energy dispersion microscopy used to conduct analyses of the chemical composition with the aim of obtaining maps of the distribution of elements and spot chemical analyses of the material. This enabled the determination of semi-quantitative chemical composition of the observed phases. The EDS detector analyses X-ray radiation that indicates the elemental composition of the tested sample.Using the X-ray diffractometer , analyses were performed of the topography and phase composition of the designed composite. Materials needed for testing were obtained from fragments of crushed samples remaining from the strength testing.Samples for SEM testing were coated with powder and fixed to the grip with the use of a carbon adhesive. Next the samples were given a circa 50 nm carbon coating as a result of cathode spraying to assure conductivity on the sample surface.The objective of the test was to find how waste cullet affects the properties of cement composite. The research population comprised three modified composites  containing various amounts of recycled aggregate . From each population 15 samples were collected. The experiment includes observations and assessment of selected properties of the sample . A granulometric analysis was carried out for glass cullet. Tests comprised assessment of the density, absorbability (humidity), compressive strength, resistance to elevated temperature, composite structure, and topography of the tested material. Chemical elements contained in the composites were identified. Granulometric determination was done on a glass sample obtained from recycling, and then a calculation was made of the degree of uniformity. Results of the sieve analysis were applied onto a semi-logarithmic grid and in such a way that a continuous grading curve was obtained  for recyThe glass aggregate curve is not contained within the area of the limiting sifting curves (upper and lower ones). The sand content of recyclate equals 1.27%. The recyclate fails to meet standard requirements of particularly good grading. The recyclate curve is below the lower limiting curve, yet that does not discriminate recyclate as an additive to concrete. The glass mixture comprises aggregate with a fraction of 0/16 mm.Steel spheres and a 5000 g analytical sample were placed in the Los Angeles drum . 500 rotBulk density (apparent density) was tested on cubic samples (100 × 100 × 100) mm. For the testing three samples of each concrete were used. Results of the test are shown in 3. The reduced density could have been caused by building up of the contact zone between the binder and aggregate. The porosity of the composite is also affected by reaction of the used aggregate and the binder. Changes in the zone of adhesive-aggregate were also observed in studies [Bulk density decreases with the increase in the amount of recyclate in the sample, and differs for all types of concrete. Cement composite C-7.5 with the addition of glass recyclate obtained a density of 2327.3 kg/m studies . However studies  certain The subsequent test comprised the determination of total absorbability (humidity) of the material by the weight method. Tests comprised 15 samples of each type of concrete. Next the samples were dried to constant mass. Constant mass is achieved when sample masses does not differ one from another by 0.1%. After saturation with water the samples were heated up to a temperature of 105 ± 5 °C for 72 h, and then they were taken out and weighed. Reinserted for 24 h. After that time, the samples were taken out and measured. A total of seven cycles of this type were carried out.The saturation time of samples and their drying are determined by standard EN 13369:2018 . The dryWater absorption varied, and for mixtures C-0, C-2.5 and C-7.5 amounted to 3.7%, 5.1% and 4.8%, respectively. The difference in results of absorbability was 1.1–1.4%. This proved that, as the amount of glass aggregate grows, the absorption of concrete also grew, most likely also leading to the formation of air voids in the concrete volume. While analysing the results of their own studies, the authors of [The figure also shows error bars with standard error that equals 0.05% for concrete C-0 and 0.07% for C-2.5 and 0.06% for C-7.5. The water absorption obtained during testing is lower than 6%. According to standards pertaining to precast concrete and sidewalk elements , they should be considered as satisfactory for any class.The compressive strength test was performed after 28 and 180 curing days of the cement composite. Samples were tested at the laboratory temperature of 20 °C. Three samples were used to determine average strength. The obtained results are presented in the bar chart .Destructive testing was carried out on samples that had not been subjected to heating. Lower values for concrete C-2.5 and C-7.5 were observed compared to reference concrete C-0 after 28 days of curing. The differences in values vary and appear to have a downtrend. Compressive strength falls with the amount of waste glass in the sample. It has been found that strength after 180 days for C-7.5 was by 3.8 MPa higher than in sample C-2.5 and concurrently lower by 10.5 MPa than for reference concrete C-0. The target strength on control samples amounted to 55.8 MPa. The conducted testing allows the presumption that a higher strength of the composite was obtained by substituting 2.5% of gravel with recyclate. Results obtained from all the tested composites may be considered to be satisfactory. The concrete was classified as C30/37, i.e., lower by one class (C35/45) or two classes (C40/50) obtained after 28 and 180 days by reference concrete C-0.The next destructive testing was performed on heated cubes after 180 days of curing. Heating was performed for three cubes each for temperatures of 200 °C, 400 °C, 600 °C and 800 °C. The heating process progressed in line with the standard temperature-time curve according to EN 1991-1-2. Temperature in the furnace was kept up for a further 60 min until the heating process was completed. Testing of average compressive strength took place at room temperature after total cooling down. An increase was observed in average compressive strength after heating the up of the samples to a temperature of 200 °C. The strength of C-2.5 concrete grew by 4.8 MPa, and for the C-7.5 concrete by 6.2 MPa in relation to the strength determined at room temperature. On the other hand, it may be considered surprising that the strength of composite C-0 increased slightly. The cement composite did not lose its properties thanks to the low coefficient of thermal expansion and the good ability of borosilicate glass to work at temperatures up to 300 °C. The impact of fire temperatures exceeding 400 °C causes a fall in strength by circa 16% (C-0), 10% (C-2.5), 8% (C-7.5). At a temperature of 600 °C the concretes were found to have a reduction of as much as by 50% compared to samples made of reference concrete.Using smaller contents of recyclate in the concrete has a positive effect on the strength of samples subjected to a fire.2 and the significance level for the given coefficient.A curve of multiple regression has been plotted for temperatures and for average strength  includinThe obtained diagrams present a negative correlation, with a visible dependence ascertained between values, for which a decrease (increase) in strength is accompanied by an increase (decrease) in temperature. The coefficient of determination is significant at the level of 0.001 for C-0, 0.002 for C-2.5 and 0.004 for C-7.5.Before commencing the heating process, all samples were dried to constant mass. The testing was conducted according to the standard temperature-time curve according to EN 1991-1-2:2005 . The samAn increase in temperature weakens the structure of the material. Cracking is visible on the sample surface. The actual distribution of temperatures shown in Thermocouples distributed in the pilot sample enabled modelling the progress of standardised fire. The thermal process was programmed by specifying the time of heating, temperature, as well as the number of process sections that should be implemented.The point at which the temperatures become balanced proves that the sample had been heated evenly throughout its entire volume. In the process of cooling down a visible increase occurs in the temperature of the internal layers .The paper presents a continuation of deliberations commenced in article , which a2 is characterised by a relatively low thermal expansion coefficient equalling circa Structural testing of the composition of heat-resistant glass (unheated at 20 °C and heated up to 800 °C) did not detect any significant changes. Glass is characterised by low resistance to the impact of alkali and significant resistance to water and strong acids. Silica glass SiO2 (22.32%), alumina Al2O3 (14.35%), sodium oxide Na2O (0.98%)  .The phase composition of concrete was determined using X-ray diffraction analysis . It is d2O and K2O) slightly decreases. The content of Al2O3 ranges from 3.68 to 4.69% which allows the statement that the tested concrete is thermally resistant.The glass composition analysis was conducted after glass was subjected to the impact of temperatures of 20 °C and 800 °C, with the determination made from point A and the area of the collected sample. The results are specified in 2) and oxides K2O, Na2O among others. In addition, peaks coming from alumina AL2O3, which enhanced mechanical, chemical and thermal properties of silicate glass were ascertained.The spectra of the chemical composition a,c confiBased on the conducted structural testing and data obtained from published studies pertaining to analyses of absorption spectra in infrared of Raman spectra, a presumption may be made that cement composite containing an additive of heat-resistant glass is less susceptible to strains resulting from thermal expansion ,73,74. T(1)The average compressive strength of concrete improved using 2.5% of waste glass cullet was found to be 48.6 MPa and 49.1 MPa, respectively, after 28 and 180 days of curing.(2)Replacement of 2.5% and 7.5% of natural aggregate (gravel and sand) with recycled aggregate allowed the attainment of concrete of class C30/37. Compared to reference concrete, a fall in strength was recorded. It may also be seen that the strength of the composite grows with the extension of the concrete curing time.(3)The most advantageous temperature of firing amounted to 200 °C. The composite was found to have an increase in strength by 6.2 MPa after 180 days of curing.(4)An excessively high temperature (800 °C) causes damage to gravel grains which caused an impairment of the properties of hardened concrete. In the composites, compressive strength decreased by circa 50%.(5)The mass loss of the C-2.5 composite did not exceed 1% . Concrete may be successfully used as a fire partition wall.(6)Testing pointed to the existence of concentrations of selected elements, which remained within acceptable levels.(7)Glass cullet (borosilicate glass) used for testing was not found to have changes to the structure and composition after the impact of temperature at the level of 800 °C.(8)The correlation between average compressive strength and temperature is significant and equals 0.004 for C-7.5 concrete.Source materials contain limited information as to the impact of fire-resistant cullet on the physical, mechanical and chemical properties of cement composite. Specific data obtained during the conducted experiment and the analysis of obtained results enable the formulation of the following final conclusions:The heat resistant glass cullet is not biodegradable and offers satisfactory performance parameters. Appropriate disposal and processing allow multiple re-use. Based on the conducted studies and analyses it has been proven that waste obtained from broken dishes may serve as perfect supplementation for aggregate of natural origin and can replace coarse aggregate used for concrete. Given environmental standards, it may be presumed that composite is an ecological full-value construction material.The authors are conducting additional tests to analyse the impact of ground glass cullet on properties of cement composite. Those studies are expected to broaden the available knowledge and to determine features of concrete not included in the programme of the present study.


A significant increase of the use of high-performance fiber-reinforced concrete (HPFRC) to strengthen reinforced concrete structures (RC) has been noted for the past few years, thereby achieving composite RC-HPFRC elements. Such a technique tries to take advantage of the superior material properties of HPFRC in the ultimate and service load regimes. Many of the existing works on RC-HPFRC elements have focused on the strength increase at the ultimate load state and much less effort has been devoted to the serviceability response. The in-service performance of RC structures is governed by the behavior of the tension chord, which determines the crack pattern  and deformations. The presence of HPFRC is supposed to improve serviceability due to its strain-hardening and tension-softening capacities. In this paper, the experimental analysis of composite RC-HPFRC tension members is dealt with. Specimens consisting of a RC tie strengthened with two 35 mm thick HPFRC layers have been subjected to loads in the service range so that the deformational and cracking response can be analyzed. The HPFRC has been a cement-based mortar with 3% volumetric amount of short straight steel fibers with a compressive and tensile strength of 144 MPa and 8.5 MPa, respectively. The experiments have shown that RC-HPFRC has higher stiffness, first cracking strength and reduced crack widths and deformations compared to companion unstrengthened RC. To understand the observed behavioral stages, the experimental results are compared with an analytical tension chord model, which is a simplified version of a previous general model by the authors consisting of 4 key points. In addition, the influence of time-dependent shrinkage has been included in the presented approach. In the last years, the use of high-performance fiber-reinforced concrete (HPFRC) as strengthening material for existing concrete structures has increased significantly ,2,3. TheThe composite action of reinforced concrete (RC) members strengthened with HPFRC layers (referred to as RC-HPFRC elements hereafter) is a complex mechanism due to the different mechanical properties of both layers and their interaction. In tension, conventional concrete has a low tensile strength and negligible softening capacity, while HPFRC typically has a three-stage tensile response ,15,16,17Most existing works on RC-HPFRC have focused on the contribution of the HPFRC layer to the ultimate capacity of composite members, which is not only due to the utilization of the tensile capacity of HPFRC for bending-critical elements, but also includes strength gains of up to 2–3 times the resistance of unstrengthened shear-critical members due to the additional mechanisms mobilized by the RC-HPFRC interaction after interlayer detachment ,19,20. IThe present paper represents a step forward in the authors’ research towards a better understanding of the composite behavior of RC-HPFRC members. Previous research ,25 has fThe main objective of the present paper is to evaluate the benefits on stiffness, cracking strength, and ability to reduce crack widths and deformations by strengthening conventional RC with HPFRC layers. Specific tests have been carried out on composite RC-HPFRC tension members under service load levels, as well as on a companion conventional RC specimen. Crack widths and deformations are analyzed to understand the improved serviceability and the potential durability of RC-HPFRC with respect to RC with the help of a novel simplified theoretical approach able to define the behavioral phases of RC-HPFRC tension members with 4 key points. A significant novelty of the model with respect to previous approaches  is the i3 of cement CEM I 42.5R, a maximum aggregate size of 12 mm and water/cement ratio of 0.5. The average compressive strength was 33 MPa at 28 days and 37 MPa at testing age (from 3 cylinders of 150 mm × 300 mm). The indirect tensile strength at testing age was 2.7 MPa (from 3 cylinders of 150 mm × 300 mm).The experimental research has studied composite RC-HPFRC tension members. The RC part has consisted of a conventional concrete prism centrically reinforced with a 16 mm ribbed steel bar (refer to The HPFRC has been manufactured from a Compact Reinforced Concrete (CRC) dry-mortar premix kindly supplied by Hi-Con A/S . The mortar is a portland cement/micro silica-based binder including super plasticizer and sand aggregates of 4 mm maximum size. The mortar was mixed with the water with a water/premix weight ratio of 0.08 and a 3% volumetric amount of steel fibers in a vertical pan mixer following the instructions of the supplier. The fibers were straight, with a length of 12.5 mm, diameter of 0.3 mm, and yield strength of 2950 MPa. The average compressive strength on 15 cm cubes was 132 MPa at 28 days and 144 MPa at the age of testing of RC-HPFRC members (from 3 cubes at each age).The tensile properties of HPFRC have been determined by inverse analysis  from 5 fThe experimental campaign included four tests on tension members. A reference test (T0) consisted of a RC specimen, while the other tests  were composite RC-HPFRC tension members. Therefore, test T0 can serve as a reference to be compared with the response of strengthened elements T1–T3. The dimensions of specimens and set-up configuration are represented in The HPFRC strengthening layers were applied when the age of the RC was 60 days. The concrete surfaces were prepared by bush-hammering to achieve adequate roughness and facilitate composite action of HPFRC and conventional concrete . The appThe specimens were stored in horizontal position, with the HPFRC layers at the bottom and top sides, in laboratory environment until the testing date. The tension tests were carried out 88 days after application of HPFRC, i.e., the total age of the conventional concrete was 148 days.The specimens were tested in tension with displacement control at a rate of 0.02 mm/s applied from the upper end with a hydraulic actuator , until a total deformation sufficient to cover the in-service range of concrete structures (strains of 1.5–2.0‰). The transducers used for the instrumentation were the following refer to : 3 LVDTsAll specimens were manufactured and tested at the Laboratory of Structures of the Technical University of Madrid, Spain (UPM).Digital image correlation (DIC) is a powerful photogrammetric technique which shows the deformation of a 2-D plain surface by taking a sequence of photographs of a speckle pattern . In the case of the RC-HPFRC specimens studied in this paper, one of the lateral sides with both the RC and HPFRC layers visible was painted with a speckle pattern consisting of randomly placed black points of 1–3 mm on a white background refer to b,c. The The global behavior of tested specimens can be represented by the load-deformation diagrams of The initial stiffness of the specimens, given by the slope of the first elastic stage, was 528 MN for T1–T3 (on average) and 318 MN for T0, which means a 66% stiffness increase provided by the contribution of the HPFRC layers. In this first stage, the composite behavior was monolithic because there were no cracks. Therefore, the stiffness increase can be attributed to the elastic stiffness of the HPFRC layers refer to .The average value of the first cracking load has been 30.0 kN for specimens T1–T3 and 19.3 kN for specimen T0, which means a significant 55% additional cracking strength achieved by the addition of the HPFRC layers. After the first crack formation, the global stiffness of the second stage of all specimens logically decreased. The average stiffness of the second stage, calculated as the slope of a secant line of the cracked part of the tests, was 24.2 MN for specimens T1–T3 (on average) and 27.9 MN for T0. The smaller secant stiffness of strengthened specimens is due to the fact that the second part departs from a higher cracking strength, but at the end of the service range their behavior tries to approximate the response of RC member, as the bridging capacity of the HPFRC through cracks and the tension stiffening contribution diminishes. Due to the testing procedure with displacement control, subsequent crack formation in specimens is accompanied by moderate load releases and subsequent reloading, which can be observed through some load oscillations in the diagrams of The number of cracks formed in the specimens has been detected with the help of the DIC technique. Two methods can be used. On the one hand, the contours of the longitudinal strains derived from the DIC analysis can be obtained, as plotted in c (c being the concrete cover). It is noted that other codes have reduced such contribution to 2c [c [The analysis of strain contours and longitudinal displacements along sections 1 to 3 has shown the following number of cracks of each specimen: 6 (T0), 7 (T1), 8 (T2), and 6 (T3). Moreover, the average crack spacing is: 11.8 cm (T0), 12.7 cm (T1), 9.6 cm (T2) and 15.2 cm (T3). Therefore, an average value of 12.5 cm has been obtained for composite members T1–T3, which is 6% higher than the crack spacing of T0. It seems that such a slight increase has been due to the larger concrete cover of composite specimens on the strengthened sides. The crack spacing calculated with the rules of Eurocode 2  would beon to 2c  and 1c [to 2c [c .It is also interesting that the strain contours and representation of longitudinal displacements b have inIn addition to the detection of crack positions, the DIC analysis offers the possibility to calculate the width of detected cracks and verify the benefits given by HPFRC strengthening. This can be done with the use of virtual extensometers bridging the two mouths of the cracks. Such a technique automatically provides the values of the displacement jumps sketched in pc = 2.5‰ in The small crack width at the HPFRC layers is indicative of the strain-hardening capacity of the material. According to the strain hardening limit derived from material characterization . In the present paper, the analytical model is limited to the strain hardening stage of the HPFRC due to the fact that its experimentally determined upper bound  until first crack formation. At this stage there is perfect bond at the interfaces (concrete-steel and HPFRC-concrete). Therefore, there are no relative slips, and the three materials have the same strain at any cross-section. Point A is characterized by the first cracking load, which takes place when the strain reaches the tensile capacity of the weakest material , i.e., εPhase 2: the concrete is cracked, while steel and HPFRC are elastic. At the cracks, the externally applied load is carried by the steel and the HPFRC. Due to concrete cracking, there is relative slip at the interfaces. For compatibility, the strain of steel and HPFRC are the same at the cracks. The first point of phase 2 (point B) corresponds to the same load as point A, but with a sudden strain increase due to the stress release at the concrete upon cracking:The horizontal transition between points A and B is a simplified approximation of the crack formation stage analogous to the one done in RC models ,42,43.ccε, refer to The end of phase 2 takes place when the elastic limit of the HPFRC is reached (pc) is reached and a macrocrack opens. The load and strain of point D can be calculated by:Phase 3: the concrete is cracked, the steel is elastic, and HPFRC is hardening. As in phase 2, there is relative slip at the interfaces, and the load is carried by steel and HPFRC at the cracks, where they have the same strain. The first point of phase 3 is point C. The end of phase 3 occurs when the strain-hardening limit of HPFRC  produces shortening of RC tension members and formation of self-equilibrated internal stresses (compression at the steel and tension at the concrete). Note that t is the time from end of concrete curing to the time of loading. According to Bischoff [cr,redF in Equation (10).c and Δσs are the internal stresses developed in the concrete and the steel. It has been extensively reported that the time-dependent shrinkage of concrete affects the behavior of tension members ,45,46. IBischoff , the loaIn case of composite RC-HPFRC members, the shrinkage effect is more complicated due to the construction sequence and the presence of two materials shrinking from different times . Such time-dependent effects have not been considered in the previous general model  and it iPhase 1: Before the instant of application of the HPFRC strengthening layers (denoted as Ut hereafter), the shrinkage of the conventional concrete produces the following shortening of the tension member and internal stresses:Ut) to the time of loading (t), both conventional concrete and HPFRC shrink. The free shrinkage strains of conventional concrete and HPFRC are εcs and εUs in absolute values, respectively. The composite tension chord is then monolithically shortened by the following strain:From the installation of the HPFRC layers  is the creep coefficient from Ut to t. The total modification of the elastic uncracked stage at the time of loading (t) can be included in the tension chord model by modifying the behavior of Phase 1 with Equations (11) and (13) for the origin offset and Equations (12) and (14) for the first cracking strength reduction Ec(tU):Phases 2 and 3: After the conventional concrete cracks, the load is carried by the HPFRC and the steel reinforcement. The behavior of Phases 2 and 3 must be modified by an origin offset (Δε’) and by the reduction of the load carrying capacity of the HPFRC  in order to easily focus on the serviceability range (F/yF < 1.0). On the other hand, the crack width has been measured at two points of the flexural crack formed at the midspan section: at the level of the longitudinal steel reinforcement and at the centroid of the HPFRC strengthening layer.In order to further evaluate the potential benefits of the application of HPFRC strengthening layers with appreciable strain hardening capacity as those investigated in the present research, the results of previous experiments on beams tested by the authors  are assepc = 1.2‰) can be noted from the tensile properties listed in The HPFRC consisted of a CRC with 2% of steel fibers. The main difference with respect to the HPFRC used in the tension members T1–T3 was the smaller number of fibers, which was responsible for the poorer tensile properties. The small hardening capacity of the HPFRC (εUh = 35 mm (the same HPFRC thickness as the one used in tension members T1–T3), the crack width at the steel reinforcement level and at the HPFRC was approximately the same from the first crack formation, without regard of the load level. Such a result is a more deficient response than the one shown in Uh = 55 mm . Nevertheless, the increase of the consumption of high-performance material to achieve this is a significant 57% (55/35-1).The relevance of the tensile properties can be discussed with the load-crack width diagrams plotted in  = 55 mm  shows thTherefore, from the comparison of the results of tension members T1–T3 with those of bending tests of , it can The in-service behavior of RC-HPFRC tension members is characterized by larger stiffness, higher first cracking strength and smaller crack widths than comparative unstrengthened RC members. According to the test results presented in this paper, the increase of initial stiffness and first cracking strength have been 66% and 55%, respectively. The widest crack widths measured at the axis of the specimens was 0.3 mm and 0.2 mm for RC and RC-HPFRC specimens, respectively. The experimental results showed that the tension stiffening contribution of RC-HPFRC members is significant and should not be neglected for serviceability verifications.The width along each single crack is smaller in the HPFRC layers than in the conventional concrete layer. According to the experimental results, crack widths were not larger than 0.05 mm at the HPFRC layers, while 0.2 mm was measured at the RC layer. Moreover, the study has demonstrated that the HPFRC can stay in the microcracking phase within the service-load range if a HPFRC mix with strain-hardening capacity is used (as in the present paper), which is rather favorable to achieve increased permeability and durability of the strengthened member.While in RC tension members the load is fully carried by the steel reinforcement at the cracks in the service load range, a non-negligible contribution of the HPFRC can also be expected in cracked sections of RC-HPFRC elements due to the strain hardening and softening capacities.From the analysis carried out in the present paper, it is fundamental to take into account the time-dependent shrinkage effect in order to fully understand the different behavioral stages of composite RC-HPFRC tension members. A simple mechanical model consisting of four key points has been proposed. An important ability of the model is the consideration of the shrinkage of the two concretes .With respect to previous research by the authors , this paA simplified model for service load domains was presented consisting of 4 hey points, which includes the complex phenomena related with the shrinkage of the two concretes .From the study carried out in the present paper, the following conclusions can be drawn:


Occupational noise-induced hearing loss (ONIHL) does not occur in isolation from other influencing factors such as health conditions and illnesses like human immunodeficiency virus and acquired immunodeficiency syndrome (HIV and AIDS), as well as tuberculosis (TB). How the burden of disease influences the occurrence and/or management of ONIHL becomes a key if the goal of hearing conservation programmes (HCPs) is to be achieved within these contexts.The purpose of this scoping review was to conduct an investigation on how the burden of disease’s influence on ONIHL is reported in literature, with a specific focus on the most prevalent diseases in South African mines – HIV and AIDS and TB.A scoping review was conducted using the Arksey and O’Malley’s framework. A search was conducted in five electronic bibliographic databases and the grey literature.The search procured 10 publications, with two specific to ONIHL within the South African context. In addition to the two publications specific to TB and ONIHL, findings revealed a serious gap in the evidence around the scoping review question globally. This obvious lack of investigations into the influence of these two conditions in the South African mining context raises serious implications about the responsiveness, and proactive nature of HCPs within this population.Considering the burden of diseases on otology and audiology is critical as certain diseases cause hearing impairment either as a primary effect, as a secondary/opportunistic effect or as a side effect of treatment options for that disease. An employee suffering from any such disease with concomitant exposure to hazardous noise levels presents an even bigger challenge to HCPs if such is not taken into consideration in the conception, implementation and monitoring of HCPs. Evidence indicates that South Africa remains one of the low- and middle-income (LAMI) countries with poor health outcomes and high mortality rates linked to the unique quadruple burden of disease , to reduce deaths related to HIV and improve life expectancy  in ONIHL and HCPs. The selected studies were restricted to the studies published in English, with a focus on these two major burdens of diseases in this population. The search consisted of the following terms: Africa, conservation, disease, HIV/AIDS, health, noise-induced hearing loss, occupational, burden, impact, effects, developing countries, mines and tuberculosis.a priori decision was made to screen only the first 10 hits (as sorted by relevance by Google Scholar) after considering the time required to screen each hit and because it was believed that further screening was unlikely to yield more relevant articles  in ONIHL and/or HCPs to determine and characterise the existing evidence base on the impact of the burden of disease in ONIHL. The second stage involved excluding from analysis the publications that described HIV/AIDS and/or TB and hearing loss in areas other than ONIHL; however, reference lists from these publications were reviewed to identify additional relevant publications. Owing to limited resources for translation, only English publications were included.For efficient time management and as recommended by Arksey and O’Malley , the firAll relevant citations for the current scoping review on HIV/AIDS and/or TB in ONIHL and HCPs after title and abstract inspection were obtained for later review of full publications. A spreadsheet was developed by the author where relevance of the publication was confirmed and where details of the publication, such as type of publication, author and publication year, title, focus and aims, methodology, context, results/recommendations and reported challenges, gaps and limitations, were mentioned. The characteristics of each publication were extracted by both researchers. Further publications were excluded at this phase if they did not meet the minimum eligibility criteria. In adherence with Levac et al.’s  frameworThe data were compiled in a single spreadsheet and imported into Microsoft Excel 2016  for descriptive analysis.This article followed all ethical standards for a research without direct contact with human or animal subjects.Current findings highlight a significant need for research in this area as indicated by paucity of evidence on highly prevalent burden of disease conditions relating to ONIHL and HCPs within the context of Africa and the world. This is despite the available evidence on the influence of HIV/AIDS and TB on hearing function within and outside the context of noise exposure . These studies, as shown in Barwise et al. , driven As far as reviews on health risks of goldminers are concerned, Eisler  simply dOf all the pillars for successful implementation of HCPs, which include periodic noise exposure measurement/monitoring; engineering controls; administrative controls; personal hearing protection; employee/management education, motivation, and training; risk-based medical examination; medical surveillance; and audiometric evaluations as well as record-keeping Amedofu, , carefulOccupational Diseases in Mines and Works Act (ODMWA). On the contrary, Elgstrand and Vingård , is the one conducted by Edwards . It quesp < 0.01) elevated compared to the control group, and that hearing thresholds over time also deteriorated significantly (p < 0.01) more in workers with TB (single and multiple treatment) than in workers without TB. These findings were recently supported by Khoza-Shangase (Brits et al. , in theiShangase  in a retShangase  uses finHuman immunodeficiency virus, TB and cancer are three of South Africa’s greatest burdens of disease (Olu et al., Occupational noise-induced hearing loss is a complex condition influenced by a number of factors, with ototoxicity being one of the key factors. Although limited research has been conducted in the synergistic effects of noise and ototoxic medications in the mining industry, sufficient evidence exists for the audiology community to increase their focus on this population and deliberate on how to ensure successful preventive measures are in place to maintain miners’ quality of life. Hearing conservation programmes naïve of the burden of disease implications fail to ensure closer monitoring of employees, individualised administrative controls for involved miners and exploration of other protective measures for employees on ototoxic treatments such as oto-protective agents; hence, implications for policy and practice reviews in HCPs are important.


Shamatha, Transcendental, and Stillness Meditation are said to aim for “contentless” experiences, where mental content such as thoughts, perceptions, and mental images is absent. Silence is understood to be a central feature of those experiences. The main source of information about the experiences is texts by experts from within the three traditions. Previous research has tended not to use an explicit scientific method for selecting and reviewing expert texts on meditation. We have identified evidence synthesis as a robust and transparent method that is suitable for this purpose. In this paper we use evidence synthesis based on expert texts to examine silence/quietness as a feature of the contentless experiences in the three practices. Objective criteria were used to select a sample of 135 expert texts. A database containing the expert descriptions of the meditation techniques and experiences was produced by extracting the relevant material from the publications and coding that material to differentiate individual features. The database, which forms part of the  Contentless experiences are often treated as pure consciousness, or consciousness itself , or narrow . The main objective was not to generate from the features higher level themes or groupings, but to explain how the experts refer to the features (whether broad or narrow) and to compare the features across the practices.The decision to employ narrative synthesis rather than one of the more specialized qualitative evidence synthesis methods was made on the basis of fitness for purpose . A key fregation , thematiynthesis , meta-etnography , and groynthesis , once inThe narrative synthesis method comprises four basic components: (a) selection of the publications for review; (b) critical appraisal – assessing the quality of the publications; (c) data extraction – extracting relevant material; and (d) synthesis – coding that material and performing any additional analyses . In the The project is compliant with the ENTREQ reporting guidelines for qualitative evidence synthesis . SupplemTraditional accounts were selected using purposive sampling . That inFor each practice, the strategy for selecting publications involved two steps: (a) identifying a limited number of authors within the meditation tradition who have outstanding qualifications as experts in the practice and who write in clear English; and (b) identifying, by way of a structured process, samples of those authors’ publications that would reveal their understandings of the practice. Those steps are described in detail below.The procedure constituted a form of critical appraisal, in that publications were only selected if the author had outstanding qualifications as an expert in the relevant practice . The ratCandidate authors were identified from scoping reading of selected publications of a broad range of authors, and from general background reading. From the list of candidate authors for each practice one or more authors with outstanding qualifications as an expert in the practice was identified. Assessment of whether an author has outstanding qualifications was made on the basis of the following criteria:•The author is recognized as an expert by other meditation experts or laypeople;•They have been in dialogue with meditation teachers or practitioners, including those regarded as senior or advanced;•They have academic qualifications or achievements (including publications) in relation to the meditation tradition or otherwise;•They hold or have held positions in relevant organizations, such as meditation bodies;•They have meditation teaching experience and expertise;•They maintain a personal meditation practice; and•They have other qualifications that are material to the assessment.For an author to be assessed as having outstanding qualifications it was required that they have high ratings on a number of these criteria. Having high ratings on at least the first two was treated as essential. It was not strictly necessary for the author to have high ratings on each of the other criteria. Having exemplary ratings on some criteria could on balance be treated as sufficient even where the author had lower ratings on one or more others.Alan Wallace stood out as having outstanding qualifications with respect to Shamatha. Five authors  stood out with respect to TM, and two authors  with respect to Stillness Meditation. In each case TW made the initial assessment, and OC and JW confirmed the decisions.stopping rules) that are applicable in the context of an evidence synthesis involving purposive sampling. data saturation, which in the present context would mean that the existing authors provide virtually all of the available insights and perspectives relating to the practices. The other is data sufficiency, which would entail that the existing authors provide insights and perspectives that are sufficient for the purposes of the evidence synthesis. Data sufficiency can take into account practical constraints, such as limitations on time and resources. Suri indicates that data saturation is rarely achieved. Data sufficiency appears to better reflect what is considered appropriate in practice.The next step was to consider whether it would be sufficient to rely on those authors, or whether others should also be included. That assessment was made having regard to rules about sample size , we determined that reviewing his publications in a comprehensive and in-depth manner would lead to a higher quality understanding than reviewing the accounts of multiple Shamatha authors at a more superficial level. Based on these considerations, it was determined that the selection of Wallace achieved data sufficiency in relation to Shamatha.The decision to focus on Wallace provides a concrete example of the way in which our method deals with the practical problem of how to reasonably limit the publications for review when faced with a very large body of expert literature. A further strength of our method is that, if other researchers feel that additional Shamatha authors may contribute further insights, they can readily extend the work to those authors using a similar process.The five TM authors provide a range of perspectives. Pearson contextualizes TM relative to historical reports of contentless experience; Shear focuses on philosophical aspects; Travis conducts empirical studies; Roth is a meditation teacher; and Rosenthal is a psychiatrist. It was expected that each author might therefore draw out unique aspects of the technique and experience. The high-level impression based on the scoping reading was that, while that is correct, the authors also present the technique and experience in broadly similar terms. Adding another author may have yielded some additional insight, but the broad similarity in the five authors’ accounts suggested that these would be marginal. Consequently, it was concluded that the five authors together provide data sufficiency.Data sufficiency with respect to Stillness Meditation was clearly achieved by the selection of Meares and McKinnon. Meares developed the practice, and McKinnon has taught it for over 35 years. Meares and McKinnon are responsible for all of the major publications concerning the practice.7. Understandings of the other two TM authors , the Shamatha author , and the Stillness Meditation authors  are spread across their publications. Relying only on their more recent materials would risk omitting important details. For that reason publications of those five authors were selected by applying eligibility criteria to lists of their full output.The next step was to select publications of the authors identified above. Three of the TM authors  have recently published major works that appear to present their understandings of the practice in a consolidated form . For thoThe primary sources for the list/s of an author’s publications were searches in online databases, and reference lists and citations from relevant publications or websites. The rationale was that those are the main sources recommended for evidence syntheses , 2013. FThe searches were designed to capture all relevant publications, meaning that iterative searches were not required (ENTREQ checklist item 3). Iterative searches involve searching for select literature, reading it, conducting further searches on the basis of that reading, and so on . In mostFathoming the Mind, which was released in October 2018. The justification for including that text was that it is a major work of more than 200 pages, and was released prior to 2019, when the analysis in the current project commenced. To the best of our knowledge, none of the eight authors published any other works that are commensurate in scale between March 2018 (the month following the searches) and March 2020 (the month in which the present paper was submitted for publication).Details of the reference lists and citations that were relied on in addition to the searches are provided in The eligibility criteria applied to each author’s list comprised inclusion criteria, and, in some cases, exclusion criteria. Publications that satisfied all inclusion criteria for an author, and that did not satisfy any applicable exclusion criteria, were selected for inclusion in the three evidence syntheses. The effect of the criteria was to excise from the full set of publications for an author at least some of the publications that were: (a) not relevant – i.e., that did not address the technique or experience; and/or (b) likely to merely duplicate relevant content from other publications in the set. To duplicate content in this context means to repeat the same idea without adding anything conceptually. It does not require word-for-word repetition.The resulting sample comprised a core set of publications setting out the main elements of the author’s understanding of the practice, in some cases together with a small number of extraneous publications. The extraneous materials were mainly publications that were likely to merely duplicate the core content, but that had not been excised via the criteria. Where final samples contained some extraneous materials, that did not matter, since those publications could be identified as part of the extraction component (see section “Data Extraction” below).The eligibility criteria included general criteria (see further below), which were the same for each author, and author-specific criteria. Author-specific criteria were utilized because they could incorporate particular features of an author’s publications in order to excise extraneous materials more effectively. As an example, the scoping reading indicated that Shear had published a major work in 1990 that appeared to present his understanding of TM in a consolidated form . On thatThe general criteria – applying for all five authors – were that the publication was a book, book chapter or journal article (not including encyclopedia entries), in English, and non-fiction. The author-specific criteria are set out in As noted above, •The author-specific criteria and the sources for the lists;•Justifications for the criteria (in addition to those provided above); and•Descriptions of how the criteria were applied at a practical level – for example, on the basis of citation, title, and abstract, or by reading the publication in full.A flowchart summarizing the selection process for all three practices is presented at TW was responsible for the initial application of the eligibility criteria. For three of the five authors , the criteria could be applied in a manner that was straightforward, with no gray areas, for example by determining whether or not a text was published from a certain year onward. The only criterion for these authors that involved any appreciable subjective judgment was the Meares inclusion criterion that the publication refers to a practice that might be reasonably identified as Stillness Meditation. For that criterion, any gray area was removed by erring on the side of including all publications for which there was any doubt.For the other two authors , applying the criteria involved more scope for subjectivity, requiring for instance an assessment as to whether the main focus of the publication (or a specific portion of it) was the meditation technique and/or experience. To address that issue, guidelines were established for how to apply the criteria for those two authors . In addiThe publications selected for inclusion in the evidence syntheses on the basis of the process above are listed in The next step in the process was to extract particular data from the selected publications. The data that were extracted included: (a) descriptions of what it is like to experience the goal-states or the interim-states fundamental in achieving the goal-states ; and (b)Information not required included theoretical, philosophical, and metaphysical understandings. That information was extracted only if it was thought necessary or helpful to properly interpret or contextualize the data relating to the techniques and experiences.In order to compare the three practices on an even footing, the evidence syntheses do not focus on features specific to meditation sessions being led or supported by a teacher. For example, a teacher in Stillness Meditation will typically use calming touch on the meditator’s head and shoulders to provide a sense of safety and reassurance , 2011. D8.The selected publications include certain participant-based academic empirical studies authored or co-authored by Shear, Travis or Wallace. Material in those studies was extracted if it indicated the expert’s understanding of the technique or experience that was separate to the participant-based findings. Across the full set of selected publications for all eight experts, material was also extracted if it was a participant-based finding about the experience of the goal-state/s, and the finding was from an academic empirical study and heavily relied on by the expert/sThe first step in the extraction procedure was to read the selected publications (or the selected portions) in full and to mark the material that was potentially relevant, adopting a broad interpretation of that phrase. The second step was to work through those sections in detail and copy or summarize the material relating to the techniques and experiences in a Microsoft Word table for each practice. The order in which the publications were reviewed for this step is described in all of the material relating to the techniques and experiences in the sections that had been marked. Material was extracted only if it added something conceptually to any material already in the relevant table. In this way, conceptual duplication of points in the table was avoided. A conservative approach was taken concerning whether material in the publications added anything conceptually to material in the table. For example, material could be taken as adding something where it:It was not necessary to copy •Expanded on or qualified a description in the table; or•Simply repeated the description, but through the repetition indicated that the feature:•was regarded as central to the practice rather than marginal;•was recognized by multiple experts; or•remained part of the practice at a later point in time.TW was responsible for the data extraction, and for the coding of the extracted material as described below (see section “Synthesis”). He was guided by regular feedback from OC and JW. OC also performed an independent review of a sample of the extraction and coding . For eacThe final step in the process was to synthesize the extracted material. Synthesis is a form of analysis that involves generating new knowledge by forming connections within extracted material that have not been made before . As refeThe technique selected for the current project was thematic analysis. This section describes the tailored form of thematic analysis that was utilized in the present evidence synthesis and how it was applied in a structured manner. The form of analysis used in the project involves several of the other techniques identified by A similar approach has been taken in the current project. On the basis that it is unnecessary and unhelpful for the purposes of the project, the first component (theory development) has been left out and no distinction has been drawn between the second and third components (the preliminary and detailed syntheses). The fourth component (synthesis assessment) is addressed in the “Discussion” section/s, independently of the guidelines.Synthesis comprised both coding of the extracted material and the steps taken to compare the techniques and experiences across the three practices. To code the extracted material, the extraction tables for the three practices were each divided into two sections: “Techniques and Interim-States” and “Goal-state/s.” As material was extracted, it was placed in one or both of those sections, as appropriate. Within those sections, the material was placed under one or more additional subject headings. For example, extracted material describing a goal-state as wakeful was placed in the “Wakefulness” section of the “Goal-state/s” part of the table. In that way it was coded as both “Wakefulness” and “Goal-state/s.”The codes “Techniques and interim-states” and “Goal-state/s” were developed deductively, meaning they were determined at the outset (ENTREQ checklist item 19). All other codes were developed inductively: They were created as required, based on the features referred to in the extracted material  indicate that the experts see that feature as reflecting at least the absence of certain types of disturbance, and possibly the absence of all forms of disturbance. To explain this point it is necessary to consider the most relevant categories of disturbance in turn.For each of the practices it is clear that terms such as silence and quietness reflect at least the absence of thoughts. 9, the experts give no indication that the conventional understanding is not applicable, and they refer to the silence as sheer, absolute, all-encompassing, and so on. On this basis it seems implied that in each practice the experts intend the term silence to extend to the absence of sounds.In the passages in the database the experts do not expressly state that the term silence reflects the absence of sounds. However, the absence of sounds is reported in each practice, the term silence is conventionally understood as meaning or including the absence of noiseall disturbances. He also says that there is “[n]othing to disturb the quiet within” .Based on the passages in the database, each of these interpretations seems reasonable. As noted above, the term silence is conventionally understood as meaning or including the absence of noise. The passages in the database provide no indication that it would be inappropriate to understand the term silence in this way. If someone reading Wallace’s reference to silence (see above) conceived that term as being only about the absence of noise, they might interpret it as reflecting only the absence of thoughts and sounds. The reason for this is that thoughts and sounds can readily be understood as forms of noise, whereas it is harder to construe other disturbances such as non-auditory perceptions, mental images, and negative feelings in that way. Sounds, as we have been using that term, are auditory sense impressions from external sources. They clearly constitute noise. Thoughts can easily be conceived as a form of internal noise. Other disturbances could possibly be treated as noise in a metaphorical sense: As the meditator approaches the goal-state/s, the disturbance – or noise – is turned down, and in the goal-state/s it reaches zero. Clearly, though, treating these other disturbances as noise is more of a stretch.10. If the person reading Wallace’s reference to silence had in mind this extended definition, they would likely see it as reflecting the absence of thoughts, sounds and other disturbances.Numerous passages in the database leave room for the term silence to be interpreted in a broader manner that extends beyond the absence of noise. In particular, they allow for the term to be interpreted as reflecting a complete calm or absence of disturbanceand the complete absence of disturbance. As such, when Wallace uses the word silence, at one level that may reflect simply that thoughts and sounds are absent, and at another it may reflect that there are no thoughts, sounds or other disturbances.One further point is that the two interpretations can co-exist. The term silence could mean the absence of noise In summary, the analysis above provides the following insights. In each practice it is reported or implied that the goal-states involve an absence of disturbances including thoughts, sounds, other perceptions, mental images, and negative feelings. The terms silence and quietness reflect at least the absence of thoughts and sounds, and this fits neatly with a conception of silence/quietness as the absence of internal and external noise. For the most part, the experts do not clearly indicate that the terms silence and quietness can extend to the absence of disturbances other than thoughts and sounds, however they also do not rule this out. Interpreting the terms in that extended manner would fit with a conception of silence/quietness as complete calm or absence of disturbance.In view of these conclusions, researchers seeking to understand silence/quietness in contentless experiences should keep in mind the potential for a single term to be used in different ways. In particular, the terms may reflect the absence of thoughts and sounds, the absence of thoughts, sounds and other disturbances, or they may have each of those meanings at the same time.This conclusion fits with the observation that there is often a degree of flexibility in the terms the experts use to describe the goal-states. The terms tend not to be defined in a rigid and very specific manner. The flexibility seems important given that the goal-states are so unusual compared to ordinary waking experiences. They are said to involve an absence of concepts and an absence of subject-object duality, and can therefore be challenging to describe , or as otherwise overlapping with them to a large extent.The experts themselves do not refer to there being four bands. We are dividing the features into four bands purely to illustrate the varying connections between the features.A key conclusion from our earlier analysis was that silence/quietness can be conceived in different ways. The experts make clear that it reflects the absence of thoughts and sounds, and they leave scope for a broader conception in which it also reflects the absence of other disturbances. The features no thoughts and no sounds can be treated as central to – or intimately connected with – silence/quietness, and for this reason they are placed in the first band. On the broader conception of silence/quietness the feature no other disturbances is also central, so it is also in that band. The absence of other disturbances is represented as a single feature, but it could equally be presented as the component features no other perceptions, no mental images, and so on.The features in the first band together represent the feature no disturbances. That feature appears equivalent or very nearly equivalent to the feature calm/ease/peacefulness. It also seems extremely close to the features emptiness/nothingness, little or no mental activity, mental rest, and stillness, where stillness is understood in the broad manner described earlier. These four features each reflect the absence of mental content such as thoughts, sounds, other perceptions, mental images, etc., but as explained above each may also have a unique experiential quality. In the diagram, the features calm/ease/peacefulness, emptiness/nothingness, little or no mental activity, mental rest, and stillness are in the second band. That indicates their extreme closeness to the features central to silence/quietness.The third band represents features that may be slightly more removed from the central features but that are still closely connected to them. The examples in the diagram are bliss/joy/happiness/goodness, security/safety, contentment, and simplicity. Bliss/joy/happiness/goodness, for instance, appears different to the central features , but it seems closely related to them, and in particular the absence of negative feelings. In Shamatha, for example, bliss or happiness is said to arise due to the mind no longer being “pummeled to death with afflictions, craving, hostility, and aversion” , p. 32.The fourth band represents features that are less closely connected to the central features. For this band, the examples are that the meditator is conscious (as opposed to not conscious), awake (as opposed to not awake), and has a degree of attentional stability and attentional vividness. These features have some connection with the absence of disturbances but it is not as close as for the other features above. For example, the feature conscious is connected to the absence of disturbances in that the meditator can only report the absence of disturbances because they were conscious of it during the goal-state. That connection is not specific to the absence of disturbances, however. There is a similar connection between the feature conscious and all the other features of the goal-states.The present paper examines silence/quietness as a specific feature of the goal-states – i.e., as one of the many features that make up the experience as a whole. It is also possible to treat the silence/quietness as the entire goal-state/s in each practice. For example, a meditator may say that they had an “experience of silence,” and mean not just silence specifically, but rather all of the goal-state features, including silence, awakeness, bliss/joy/happiness/goodness, and so on. Researchers wishing to understand silence/quietness in this much broader sense would need to examine all of the goal-state features in detail. Our database contributes to this endeavour by identifying each of the goal-state features in the traditional accounts, and showing how the experts refer to them.The analysis above is grounded in our findings concerning how silence/quietness is referred to in the database. Readers can have confidence that the findings accurately reflect how the feature is conceived within the traditions because the database and findings have been generated using an appropriate scientific method. The database represents a stronger evidence base than traditional descriptions identified by researchers in an unsystematic and/or opaque manner.The method is both rigorous and transparent. Rigour is ensured by relying only on experts with outstanding qualifications; using objective criteria to identify samples of those authors’ publications that reveal their understandings of the practices; working through those publications systematically and in fine detail in order to extract relevant material; and fully coding the extracted text. Transparency is provided by documenting each element of the process, satisfying the ENTREQ reporting guidelines, and making the full method and database available.In our analysis we conclude that certain aspects of the experts’ understandings are unclear. For example, it is unclear exactly if and when the experts intend the words silence and quietness to extend to disturbances other than thoughts and sounds, and it is unclear precisely how silence/quietness differs from stillness. The discovery of these ambiguities represents a strength of our method. A more superficial approach would likely fail to recognize the fine distinctions to which they relate. Identifying the ambiguities helps to generate research questions that can be examined in future studies to provide greater clarity (see section “Future Research” below).There are three main limitations of the evidence synthesis.The method incorporates a series of structural elements designed to provide an objective basis for making decisions relating to the selection, extraction, and synthesis of expert texts or material within them. These include numerous rules applied by one of our team members and independent assessment by a second team member, for a sample of publications, to identify any issues with the first team member’s decisions. A limitation of the method is that there remains a degree of subjectivity in how the rules are applied. As an example, our judgment that a description concerns what it is like to have an experience and should therefore be extracted may differ to the assessment of other researchers.All forms of evidence synthesis involve a degree of subjectivity . A strenWe have aimed to be as transparent as possible. The transparency allows others to critique or audit the process and see if the findings replicate. If experts in or outside the traditions consider that any facet of the method or its application is problematic, they are free to argue that point.The second limitation is that the method involves selecting and reviewing only a sample of the traditional publications for the three practices rather than all of them. As noted earlier, the large number of traditional publications for the three practices means that it is not feasible to review them all. Examining additional publications (outside the sample) might clarify some aspects of the goal-states. However, the sampling strategy was explicitly designed to ensure that the selected publications allow a deep understanding of how the experiences are described in each practice.The third limitation is that there are various issues concerning the reliability of the descriptions of meditation experiences in the database. The data and findings allow us to address our specific research question, namely, “How is the silence of the goal-states described in the traditional texts?” However, it cannot be simply assumed that the descriptions in the traditional publications reflect with a high degree of accuracy the experiences that meditators have in practice.For example, the traditional descriptions are likely to be normative to some degree and can be influenced by doctrinal considerations . In addiThe traditional accounts also have certain strengths when it comes to reliability. For instance, typically they take into consideration the expert’s personal experience during meditation and the experience of large numbers of other meditators, such as students, patients, or peers of the expert. The experts will often describe a particular feature of the experience and then provide examples from individual meditators (quoted or paraphrased) to support those descriptions. In numerous cases the reports from the individual meditators relate to a specific experience at a particular point in time.micro-phenomenology, which claims to provide “great precision”  The experts frequently present it alongside other features; (b) The terms silence and quietness are often used without elaboration as to their precise meaning; (c) The experts suggest that it has a particular connection to stillness, and the absence of concepts, mental activity/noise, thoughts, and disturbance; and (d) They indicate that it is in some sense complete.Analysis of the findings led to the following additional insights. The terms silence and quietness reflect the absence of thoughts and sounds. In general, the experts do not clearly indicate that the terms can extend to the absence of other disturbances, but they leave room for that interpretation. It is not clear from the expert texts exactly how the feature silence/quietness is distinct from other features such as stillness that may also reflect the absence of disturbances. As a separate matter, the absence of disturbances can be treated as central to silence/quietness, but silence/quietness is also connected to the other features of the goal-states in varying degrees.As shown by the findings and insights above, the evidence synthesis identifies fine distinctions and areas of ambiguity within the expert texts. These lead to new research questions which can be investigated in participant-based studies or other text-based studies with the aim of achieving greater clarity. The findings, insights, and paths for future research in this paper demonstrate the value of investigating silence/quietness using evidence synthesis.All datasets generated for this study are included in the article/TW wrote the first draft of the manuscript and compiled the database. All authors contributed to the conception and design of the project, and to manuscript revision.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Despite recent progress in hepatitis treatment, there have been no significant advances in the development of liver cancer vaccines in recent years. In this study, we investigated the regulatory effect and potential mechanism of hepatocyte growth factor receptor  on tumor vaccinations for liver cancer in mice. Herein, we demonstrate that MET expression is significantly associated with the immunogenicity of liver cancer in mice and humans, and that MET depletion dramatically enhances the protective efficacy of chemotherapy-based anti-liver cancer vaccination. Mechanistically, MET repressed liver cancer immunogenicity independent of the traditional PI3K–AKT cascade, and MET interacted with vacuolar ATP synthase (V-ATPase) and mediated the activation of mammalian target of rapamycin (MTOR), thus suppressing liver cancer immunogenicity. The efficacy of chemotherapy-based liver cancer vaccination was markedly enhanced by targeting the MET–V-ATPase–MTOR axis, highlighting a translational strategy for identifying MET-associated drug candidates for cancer prevention. Further research on liver cancer vaccines has been primarily hindered by limited knowledge of the molecular mechanisms that drive the suppression of liver cancer immunogenicity. Herein, we focus on MET, an important receptor tyrosine kinase (RTK) and the receptor of hepatocyte growth factor (HGF).8 After binding to HGF, MET is activated via dimerization and autophosphorylation to initiate downstream signaling pathways.9 Ample evidence has shown the significance of MET in liver development and oncogenic transformation, as well as its role in therapeutic resistance;13 thus, the current study was aimed at determining the effect of MET on liver cancer immunogenicity and the protective efficacy of liver cancer vaccination.The early diagnosis and therapeutic management of liver cancer remain challenging tasks due to the high fatality rate of this cancer.14 and thus, it has been recognized as a pivotal factor for controlling metabolite-dependent cell growth.15 Indeed, hyperactive MTOR signaling is frequently observed in cancer pathology.17 Many factors regulate MTOR activation in different physiological and pathological conditions, including but not limited to KLHL22, SAMTOR, and Sestrin2;21 however, the potential influences of MTOR on tumor vaccination have rarely been characterized. Herein, we identify an AKT-independent MET–MTOR signaling pathway useful for determining the efficacy of liver cancer vaccination. We found that MET serves as a central component of the MTOR complex, independent of the PI3K–AKT cascade, and participates in MTOR activation by interacting with V-ATPase. We also demonstrate that the newly discovered MET–V-ATPase–MTOR signaling pathway more strongly suppresses liver cancer immunogenicity than does the traditional MET–AKT–MTOR pathway.The mechanistic  target of rapamycin complex (MTORC) is critical for sensing multiple variables related to metabolism,Met-KO) H22  mice and in immunocompetent C57BL/6 mice, respectively  and MET-depleted , a public web portal based on The Cancer Genome Atlas (TCGA), to analyze the relevance of MET to multiple immune features across 30 cancer types. Consistent with the mouse data, the expression levels of MET in clinical samples exhibited a negative correlation with the relative abundance of most tumor-infiltrating lymphocytes (TILs) Fig. , major h23 In the present study, using a pre-setup protocol , but not cisplatin (CDDP), has been reported as a viable treatment that serves as a tumor vaccination in several cancer types, as observed by OXP induction of the immunogenic death of cancer cells and activation of tumor immunogenicity.col Fig. , we obsecol Fig. . Intrigucol Fig. . Similarlls Fig. .Fig. 3ME24 To determine whether MET-controlled liver cancer immunogenicity is mediated by the AKT signaling pathway, we introduced the AKT constitutively activated mutant T308D/S473D (AKT-DD) and repeated the experiments described above , exerts its functions mainly through its pivotal downstream executor in the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)–AKT cascade.ove Fig. . Unexpecove Fig.  or the Hove Fig. . These r+-adenosine triphosphatase ATPase (V-ATPase) complex, including subunits A, B, D, E, F, G, and H (but not C), was immunoprecipitated with MET  were individually immunoprecipitated and subsequently analyzed using tandem mass spectrometry (LC–MS/MS). The candidate proteins  were selected, and the data were overlapped in a Venn diagram Fig. . IntriguMET Fig. . Concomi18 To identify the subunit in the V-ATPase complex that dominates the interaction with MET, we performed bidirectional immunoprecipitation experiments with antibodies against MET  and GRB2-associated-binding protein 1 (GAB1).29 To determine whether the V-ATPase complex could interact with MET via the PxPP motif, we retrieved the sequences of the V-ATPase complex. Notably, none of the subunits of the V-ATPase complex contained a PxPP or analogous motif   -centric lysosomal sensing machinery Fig. . Further01) Fig.  and ATP601) Fig.  in clini32 MTOR phosphorylates S6K1 at Thr389, and activated S6K1 further phosphorylates RPS6 to regulate protein translation, synthesis, and metabolism.15 To investigate the role of MET in MTOR activation, we used WT and Met-KO HepG2 cells and observed that the amino acid-enhanced phosphorylation of S6K1 at Thr389 was repressed in MET-KO cells  kinase 1 (S6K1).lls Fig. . A simillls Fig. . We furtlls Fig.  and MET-lls Fig. . These r33 Forced expression of constitutively active the Rag GTPase mutant Q99L (RagBGTP) rescued S6K1 phosphorylation at Thr389, that had been abolished due to MET depletion  enhanced chemotherapy-based vaccination induced by the WT H22 cells (80% for the OXP-treated cells and 50% for the CDDP-treated cells)   and thus creates a tumor microenvironment resistant to immune attack.ls) Fig.  and Hepals) Fig. . Howeverls) Fig.  and Hepals) Fig. . Consistls) Fig.  and Hepals) Fig. , similarls) Fig.  and Hepals) Fig. , similarin vitro. First, we analyzed the impacts of mTOR inhibition on MET-deficient cancer cells. WT and MET-KO HepG2 cells were individually treated with or without RAPA, and subsequently, the cell proliferation, viability, and colony formation capacity were analyzed. The results showed that, compared to that of the WT control, RAPA markedly inhibited the proliferation of the MET-KO cells  axis and the MTOR signaling pathway.46 For instance, both growth factors and MTOR signaling strongly inhibit autophagy and prevent insufficient energy conversion and unnecessary physical dissipation under normal conditions or metabolic stress.49 Nonetheless, the intracellular relationship between the growth factor–receptor axis and MTOR signaling pathway has not been fully understood .50 For instance, at least in glioma, EGFR activates MTOR and its downstream substrate RPS6 through PKC, independent of AKT, which raises questions about the necessity of AKT as a critical intermediate for coupling the EGFR activation and MTOR signaling.51 In the current study, we also established that HGF enhances MET lysosomal translocation, where it interacts with ATP6V1A to regulate MTOR activation in an AKT-independent manner. Considering the dominant role of MTOR in metabolic processes, this finding may help us better understand MET-driven functions, especially in metabolism-controlled immunity, and may ultimately assist in formulating strategies for the development and use of MET-targeted therapies.Growth factor receptors (growth regulatory elements) are activated by corresponding ligands (sometimes multiple ligands), and they transduce outside signals for cellular proliferation, survival, and differentiation into cells.53 However, the MET-binding motif was not specifically identified. MET substrates predominantly bind in proline-rich regions (PxPP).27 Unlike AKT (RXRXXS/T), AMPK (LXRXXS/T), and PKC [(R/K)(R/K)X(S/T)X(R/X)], the domains available to determine the potential substrates of MET are extremely limited.54 Therefore, more detailed studies are warranted to fully understand the association between MET and the V-ATPase complex.Another pivotal observation of this study suggests that the phosphorylation state of MET determines its level of interaction with the V-ATPase complex. To our knowledge, this is the first report showing an interaction between MET and the V-ATPase complex in a phosphorylation-dependent manner.Supplementary Material