It was concluded that the weight loss % was greatest for jute fibers when used in concrete composite, while there was no significant effect on the basalt fiber samples. The strength of jute fiber in the concrete sample was also most severely affected by the aging process, compared to other fibers. The strength of basalt fibers in a concrete composite was least affected by the aging process. In some cases, the sisal fiber sample showed an increase in fiber tenacity after the aging process due to fibrillation, which might have increased the interfacial area. The fiber microstructure before and after the aging was evaluated through the use of scanning electron microscopy (SEM). SEM analyses of different fibers were carried out to investigate surface degradation. The fiber pull-out strength was found to be the greatest for basalt fiber, followed by jute and sisal. This is indicative of the excellent adhesion of such fibers with cement in a concrete composite. In these cases, the use of sisal fiber results in defibrillation and increased specific surface area. Sugarcane and coconut fibers ruptured due to their inherent weakness and provided only a small increment in the mechanical performance of the concrete. Basalt fiber-reinforced concrete offered the greatest compressive strength, followed by jute and sisal. These observations provide crucial information regarding the durability and aging of natural fiber-reinforced concrete.This paper presents an experimental study on the influence of alkaline environments on natural fibers of plant and mineral origin in concretes. The durability of concrete-based composite materials is influenced by the properties of the reinforcing fiber, and the serviceability of concrete is dependent on its durability. The aim of the present study is to investigate the strength, weight loss %, and surface degradation of jute, sugarcane, coconut, sisal, as well as basalt fibers through an accelerated aging method when used as reinforcements in concrete. The samples were immersed in an alkaline environment of sodium and calcium hydroxide at two different levels of pH for one week. Further, the fibers were immersed in NaOH and Ca(OH) Concrete is one of the most important construction materials around the globe, but it has some deficiencies, such as brittleness and relatively low impact resistance, tensile strength, fire resistance, durability, and resistance to crack formation. These weaknesses can be overcome by using fibers as reinforcements. In recent years, steel has been used as a reinforcement material in cementitious composite, but it is susceptible to corrosion, which reduces its durability . Many me2 emissions around the world [3 and 10,920 kg/m3, respectively. In contrast, textile-reinforced concrete (TRC) has a lower embodied energy and carbon value, i.e., 3160 MJ/m3 and 340 kg/m3, respectively [The global construction sector consumes 40% of all materials and energy ,4. The phe world . The steectively . Textileectively . Naturalectively . Plant fectively ,13,14,15Plant-based natural fibers are classified as stalk/stem/bast fibers , leaf fibers  and seed–hair/fruit fibers . Jute is a type of bast fiber that is extracted from the outer cell layer of the plant stem. It can be used as a reinforcement in concrete structures, such as in the case of textile reinforcement concrete (TRC). Many researchers have used jute as a reinforcement in concrete to increase its flexural and tensile strength . Sugarca2 is an inorganic material having a -OH (hydroxyl) group on the surface which migrates to the fiber structure. Cement becomes highly alkaline in wet environments (the pH of wet concrete is between 11 and 13). Several investigations on the long-term performance of concrete reinforced with fibers, especially natural fibers, have been reported [Cement is an alkaline matrix. Ca(OH)reported ,24. Howe2 resulted in reduced mechanical properties for jute and polyester yarn specimens. Jute yarn underwent hydrolysis and dissolution of lignin, hemicellulose, and cellulose, whereas polyester yarn underwent hydrolysis associated with polymer chain scission [In previous research, accelerated aging of concrete structures reinforced with different materials was reported . The durscission . The degscission .Based on the available literature, a research gap was identified. The main objective of the present work is to study the ageing of plant and mineral fibers when exposed to an alkaline environment and the effect of this ageing on the durability of concrete materials. The effect of an alkaline environment can be assessed by a comparison of the mechanical performance before and after exposure, as recommended by other researchers . An analPlant-based natural fibers such as jute, sugarcane, coconut, sisal, and mineral fiber, i.e., basalt, were selected for this investigation. The coconut fibers, jute fibers, and sugarcane fibers were purchased from a local market in Faisalabad, Pakistan. Sisal fibers and basalt fibers were supplied by Nanning Jie Cheng Hang Co. Ltd., Nanning, Guangxi, China. Apart from sugarcane fiber (bagasse), none of the materials required further processing. Sugarcane bagasse was obtained from agricultural waste after the juice had been extracted from it. After cleaning and processing, the fibers were cut to the required length of 30 mm ,36,37. TSeveral properties of the fibers used in this research were evaluated in the laboratory, while some others were taken from information provided by the suppliers. Before characterization, all the fibers were conditioned at 25 °C and 65% relative humidity. Fiber properties were measured by ASTM standards ,48,49,502), of analytical grade. These were purchased from a local market in Faisalabad, Pakistan. Although calcium hydroxide is the alkali which is most prevalent in cement, sodium hydroxide was also used to gain a better understanding of the effect of a rigorous alkaline environment on natural fibers. To quantify the limits of the fiber degradation, accelerated aging tests were performed on basalt, jute, sisal, sugarcane, and coconut fibers.The alkalis used for the treatment of the fibers were sodium hydroxide and calcium hydroxide From a chemical point of view, plant fibers consist of cellulose, lignin, and hemicellulose. The rest is pectin, wax, and several other impurities. The characteristics of cellulose, hemicellulose, and lignin in plant fibers play an important role in determining their mechanical, chemical, and thermo-mechanical properties. Cellulose consists of covalent-bonded pyranose rings in each glucose unit. The molecular chains, mutually connected by hydrogen bonds, constitute the microfibers, which are bound to each other by hemicellulose and lignin. Cellulose has a crystalline structure , depending on the source. Due to its structure, cellulose is quite rigid at the molecular level and exhibits relatively higher resistance to tensile stresses. Cellulose is almost insoluble in alkaline solutions, while hemicellulose dissolves easily. Hemicellulose is a branched short-chain polymer which is highly reactive and non-crystalline in nature. Lignin is a hydrophobic natural adhesive that is present in plant fibers and is soluble in alkaline solutions to a limited extent. Lignin actually works as a glue between cellulose and hemicellulose and helps the material to gain rigidity ,52. A co2) content, followed by Al2O3, Fe2O3, Na2O, CaO, and MgO. Basalt fibers are composed of several oxides, as shown in Basalt is a mineral fiber with a high silica 2 solutions of 1 M, 2 M, 4 M, an 6 M concentrations for 48 h in order to investigate the gradual effect of an alkaline environment on the mechanical properties of the fibers. After removal from the alkali solution, the fibers were neutralized by treatment with acetic acid. Any residual alkaline material was removed by washing the fibers with distilled water. The fibers were dried after treatment in an oven for 30 mins and then further dried in air for 24 h for further investigation. For each sample, 10 measurements were carried out and the average was reported.All the fibers were dried (to remove any moisture) and weighed using a digital balance with an accuracy of 0 ± 0.1%. The fiber length was measured carefully. Fiber samples of 30 mm in length were immersed for 1 week in an alkali solution in tight plastic containers to prevent evaporative losses. NaOH solution with 98% concentration and Ca(OH)2 on different fibers such as basalt, jute, sugarcane, sisal, and coconut was studied under different pH levels and different molar concentrations. Notably, the reduction in strength and weight were used to study the effect of alkali treatment on the selected fibers. The strength and weight loss % were measures, and a microscopic analysis of the fiber surfaces before and after chemical exposure was conducted.The effect of treatment with NaOH and Ca(OH)WL is the weight loss, W1 is the weight of sample before treatment, and W2 is the weight of the sample after treatment. For each sample, 10 measurements were carried out and the average was reported.The test sample were weighed before and after alkali aging to quantify the weight loss. Weight loss of the samples was calculated using the formula:The breaking tenacity of different fibers was measured using a universal materials testing machine , according to the ASTM D3822M-14 standard . Fiber sSEM was used to investigate the degradation of the surface of fibers after treatment with alkali solutions. SEM images were taken in the range of 100–500× at 100 micrometers. Microstructural images were prepared for different types of fibers before and after the alkali treatments. The samples were prepared with a sputter, i.e., Quorum Q150R ES, which uses gold-plating with an argon gas atmosphere. The thickness of the gold plating was kept at 2 nm using a current of 20 mA. A Quanta 250 scanning electron microscope was used for this purpose. The samples were visualized in a nitrogen atmosphere with a secondary electron (SE) detector, using an acceleration voltage of 20 kV.For the concrete samples, ordinary Portland cement (OPC) was used. The conventional procedure of chemical analysis for cements normally involves a tiresome process during the preparation of the samples. In this study, the concentrations of elements in cement were determined by the inductively coupled plasma-optical emission spectroscopy (ICP-OES) method ,37. ThisThe concrete samples were prepared by mixing the cement and fibers with water, i.e., 60% water, 38% cement and 2% fiber by weight were mixed. The mixture was stirred thoroughly using a glass rod for about 30 min and then allowed to hydrate in sealed plastic containers. Five parts by weight of the concrete mixture (water + cement + fiber) and four parts by weight of alkali were mixed as recommended by the supplier. Then, 2% weight of fiber was added to the concrete mix for each kind of cellulosic and mineral fiber reinforced sample. Further, a reference/control sample was also prepared without fiber. The samples were removed from the mold after 48 h of curing at room temperature and then dried again for 48 h at room temperature.As per the literature, there is no standard method to check the pull-out strength of fiber from concrete. Based on the available related literature, a suitable method was developed to perform these experiments ,45. FibeSamples of size 52 mm × 52 mm × 52 mm were prepared for concrete blocks reinforced with 2% weight of natural fibers, as well as plain concrete without any fiber (control sample). The compressive strength was measured using a digital-display hydraulic universal testing machine (Model: Beijing Sinofound WES-100) using test standard ASTM C109/C109M-07 . A loadip > 0.05), while the alternate hypothesis (H1) means the opposite of null hypothesis, i.e., a statistically significant difference was observed among the measured data with (p < 0.05). The analysis was carried out keeping a 95% confidence interval, which ensures significance of the studied factors if the p value is below 0.05.Each experiment was executed ten times, and average was considered as the response variable. In order to analyze the effect of alkalinity on fiber tenacity, analysis of variance (ANOVA) was used to ensure the significance of the test results. To evaluate the test data, the Minitab version 21.1.0, Statistical software package was used. The null hypothesis (H0) means a statistically insignificant difference among the measured data with 2.It was visible that NaOH at all concentrations had a more severe effect on the natural cellulosic fibers as compared to Ca(OH)2, which might reduce the strength of basalt fibers, even though there was no significant weight loss in basalt fiber, as cations of the reaction mixture bind to the fiber silicate structure. For example, when the fibers were treated with alkali, the network structure broke and cations  moved freely in the solution, because Na+ and Ca2+ cations have comparable dimensions; this is why cations of Na+ replace Ca2+ in the network structure. These replacements of cations in the network structure of basalt might marginally reduce the mechanical properties but do not affect its weight [After the accelerated aging process, mechanical tests were conducted to quantify the tenacity of each type of fiber. The tenacity of single untreated fibers was compared with that of alkali treated fibers of the same type. The results demonstrated that the tenacity of the fibers reduced after the aging process. The basalt fibers showed a minimal reduction in mechanical properties as compared to other natural cellulosic fibers. The marginal reduction in mechanical properties in basalt fibers may have been due to their crystallographic structure. The structure of basalt fiber is produced by single tetrahedron olivine, linear chain pyroxenes, and tetrahedral structure gioclase. Some bonds of linear tetrahedrons break down in an alkaline environment, causing a minor reduction in the mechanical properties. The formation of oxides occurs when Fe reacts with Os weight ,58,59,602 of 1 M, 2 M, 4 M, and 6 M concentrations for 48 h to investigate the gradual changes. The results are shown in Further, the tenacity of the fibers was also evaluated after treatment with NaOH and Ca(OH)The strength and stiffness of fibers are directly related to their cellulose content and crystallinity index. A higher crystallinity index means a lower amount of amorphous regions. Fibers exhibit minimum reactivity because they are highly crystalline, thus rendering fewer hydroxyl groups available for reactions with interacting chemicals ,62,63.As the cement slurry is a highly alkaline matrix, quick deterioration of mechanical properties of the fibers may occur if they have high hemicellulose content. Mainly, the hemicellulose  is degraded and lost in a alkaline environment. Free hydroxyl groups of cellulose-OH- result in an undesirable hydrophilic characteristic in fibers. Hydrogen atoms in the free hydroxyl groups are replaced by sodium/calcium atoms. Due to alkali reactions, hydrogen bonds in the crosslinked networks of the cellulose and lignin structure are broken. This makes the fiber soft, which also leads to a decrease in tenacity. In addition, the alkaline condition affects the hydrogen bonding in the chemical structures of natural cellulosic fibers, resulting in an increase in fiber surface roughness. The reaction of cellulose with alkali is as follows:Among all the plant fibers used, the reduction in mechanical property was maximal in jute, followed by sugarcane. Jute is a lignocellulosic fiber in which the lignin content is 13.1%, the cellulose content 62%, and the hemicellulose content is 24%. The alkaline solution dissolved the hemicellulose present in the jute fibers. Strong alkaline solutions also cause the hydrolysis of cellulose, which results in the degradation of the fibers ,64,65. A2. These observations were consistent with previous results [2 in 1 M, 2 M, 4 M, and 6 M concentrations for 48 h and after 1 week treatment with both alkalis at high concentrations. These results indicate the excellent performance of mineral fibers, e.g., basalt, as reinforcement materials in concrete.It was evident that NaOH caused more severe damage to the cellulosic fibers and thus caused reduction in tenacity compared to treatment with Ca(OH) results ,69,70. Bp value of the results was α = 0.00, which is below 0.05, and clearly shows that the results are significant and the effect of accelerated aging on fibers is significant (R square is 95.41%). A greater R-square indicates greater effectiveness of the treatment.The ANOVA results showed that the alkali concentration and its pH had significant effects on the mechanical properties of fibers used in concrete. The The surface morphology of the fibers was also investigated using scanning electronic microscopy. Microscopic images of different types of fibers before and after alkali treatment are shown in appf), [d designates the fiber diameter, and el is the embedded fiber length inside concrete block.The bonding between the concrete matrix and the reinforcing fibers determines the pull-out behavior. A strong adhesion and interfacial bonding between the reinforcing fibers and the concrete or cement matrix is key to stability and performance under tensile/compressive load. Weaker bonding may lead to deboning and easy pull-out of the fibers. If the interfacial strength between the fibers and the matrix is too high, the fibers might rupture when there is crack initiation. In the opposite case, if the interface is too weak, the fiber reinforcement is easily pulled out of the concrete. Therefore, the bond strength determines the mechanical properties of fiber-reinforced concrete. Pull out tests are useful to obtain information about the load transfer between the cement matrix and the fiber reinforcement. These tests characterize both pull-out and rupture of the textile fiber as different failure modes. The peak load is not necessarily the breaking point of the fiber itself, but rather, the load at initiation of cracking . Traditifapp), .ґapp = appr values calculated using Equation (3) usually distinguish between “good” and “poor” bond strengths and provide an estimation of the efficiency of interfacial bonding between the cement matrix and the fiber. The appr values obtained for the different types of fibers are given in The appґ) levels can be reached at high levels of deformations. It was observed that the adhesion performance of basalt and jute fibers was superior to that of other types of fibers. This could be predicted based on the basic of mechanical properties of such fibers and the Halpin-Tsai equations governing the performance of composites/concrete reinforced with fibers. The Halpin-Tsai model is commonly used to predict the compressional strength and modulus for composites with defined fiber alignments [cK is the effective compressional property of the composite/concrete, while fK and mK are the corresponding fiber and matrix compressional properties; fV denotes the fiber volume fraction, and ζ is a geometrical parameter which represents the reinforcement geometry, packing geometry, and the loading conditions.In the case of basalt fibers, very small slippage (displacement) was observed, as they have excellent adhesion with the cement matrix. The maximum tensile stress was the highest in the case of basalt fibers. A similar situation was observed in the case of jute fibers, but in this case, the maximum force recorded was much lower than that of basalt, as jute fiber has an overall lower strength value. In case of sisal and sugarcane, much higher slippage/displacement/deformation was observed. Such large displacements prior to material failure are crucial with regard to structural safety as well as energy dissipation, particularly in the case of dynamic loading in concrete. Higher strength . The results are given in For all the concrete samples reinforced with 2% weight of different types of fibers , the compressive strength was higher than in the control sample. The maximum compressive strength was observed for the 2% basalt fiber-reinforced concrete sample, followed by the jute and sisal fiber-based samples. The blocks prepared with sugarcane and coconut fiber-based concrete exhibited the lowest compressive strengths, even though these values were higher than those of the control sample. These findings are in accordance with theoretical/numerical estimations based on the Halpsin-Tsai models ,72,73,74The inherent mechanical properties of the fibers seemed to improve the compression behavior of concretes reinforced with different types of cellulosic/mineral fibers. These observations were consistent with the results of the Halpin-Tsai equations and findings from other researchers ,32,45. BFiber reinforced concrete is of prime importance in the construction sector. Fiber is used as a reinforcement in concrete retrofitting, serving as an internal and external reinforcement in concrete structures. It is gradually becoming an important part of the construction industry. Different lignocellulosic fiber materials are found all over the world, either as wood or agricultural waste. In this study, the durability of different lignocellulosic fibers and mineral fibers were investigated, and tests were performed to quantify the weight and strength loss of the fibers before and after undergoing an accelerated aging process. Based on the results, the following conclusions are drawn. The percentage of weight lost after the aging process was greatest in the cases of jute and sugarcane fibers. There was no significant weight loss in the case of basalt fibers after the aging process. The tenacity of jute fibers was affected the most after the aging process. Coconut/coir fibers showed minimum reductions in strength, while the tenacity of sisal fibers sometimes increased after the aging process due to fibrillation. SEM images showed degradation of the fiber surface, a reduction in diameter, and the development of small voids on the surface of fibers after the aging process, especially in the case of jute fibers. It is important to consider the chemistry of plant fibers to achieve greater durability of concrete. The pull-out strength was found to be greatest for basalt, followed by jute and sisal fibers. This is indicative of the excellent adhesion of such fibers with the cement in a concrete composite. Sisal fibers resulted in defibrillation and an increase in specific surface area, thus increasing the interfacial strength. Sugarcane and coconut fibers ruptured due to their inherent weaknesses. The compressive strength of basalt fiber-based concrete was found to be the greatest, followed by jute and sisal based concrete samples. The experimental findings were validated by numerical/theoretical models based on Halpin-Tsai equations. These observations broaden our understanding of the compatibility of natural-origin cellulosic as well as mineral fibers in concrete materials and help in determining the durability and aging of natural fiber-reinforced concrete under alkaline conditions. Natural fiber reinforced concrete may be an alternative sustainable construction material in the future.


These technologies include the production of geopolymer concretes. The purpose of the study was a detailed in-depth analytical review of studies of the processes of structure formation and properties of geopolymer concretes in retrospect and the current state of the issue. Geopolymer concrete is a suitable, environmentally friendly and sustainable alternative to concrete based on ordinary Portland cement (OPC) with higher strength and deformation properties due to its more stable and denser aluminosilicate spatial microstructure. The properties and durability of geopolymer concretes depend on the composition of the mixture and the proportions of its components. A review of the mechanisms of structure formation, the main directions for the selection of compositions and processes of polymerization of geopolymer concretes has been made. The technologies of combined selection of the composition of geopolymer concrete, production of nanomodified geopolymer concrete, 3D printing of building structures from geopolymer concrete, and monitoring the state of structures using self-sensitive geopolymer concrete are considered. Geopolymer concrete with the optimal ratio of activator and binder has the best properties. Geopolymer concretes with partial replacement of OPC with aluminosilicate binder have a denser and more compact microstructure due to the formation of a large amount of calcium silicate hydrate, which provides improved strength, durability, less shrinkage, porosity and water absorption. An assessment of the potential reduction in greenhouse gas emissions from the production of geopolymer concrete compared to the production of OPC has been made. The potential of using geopolymer concretes in construction practice is assessed in detail.The concept of sustainable development provides for the search for environmentally friendly alternatives to traditional materials and technologies that would reduce the amount of CO Therefore, there is a significant increase in the number of studies on geopolymer concrete, and an increase in the volume of new experimental and theoretical data about it, which need to be systematized.(2)The practical applied research problem lies in the fact that such insufficiently deep knowledge and systematization of existing ideas do not allow in some way to unify and standardize certain approaches, technologies and compositions, although this could in principle be done to improve understanding in the world community of efficiency and correct use of geopolymer concretes and geopolymer technologies.The current problem of modern construction and production of building materials, products and structures is the low degree of environmental friendliness of construction processes, products, materials and structures. Thus, the world community represented by engineers, scientists, technologists, and materials scientists is aimed at obtaining environmentally friendly, highly functional materials for various industries, including construction. In this regard, it is difficult to overestimate the role of geopolymer concretes. Geopolymer concretes are a relatively new, but already well-proven way to considerably improve the ecofriendly affability and economy of structure. The thing is that these geopolymer concretes are based on the clinker-free technology of binders. In their composition, they combine industrial and other types of waste, as well as other environmentally friendly methods of production and obtaining new buildings and structures. All this gives a complex ecological and economic effect. Thus, the significance of the study is a result of the international environmental agenda and the desire of construction and production around the world to reduce resource costs: labor and material costs. The problem raised in the study consists of two aspects:2, the emissions of which are the main cause of global warming, along with deforestation and burning of fossil fuels 4− and [AlO4]5− tetrahedra, interconnected by oxygen bridges. Si-O-Al compounds are closed in chains and rings. Positive ions  compensate for the negatively charged four-coordinate Al. In the course of the studies conducted using the methods of thermal analysis, nuclear magnetic resonance, and mercury porosimetry, it was found that the pores of geopolymer compositions contain water and sodium or potassium cations that have not entered into a chemical reaction with the binder. When dried, they migrate to the surface of the material and undergo atmospheric carbonization, which is the cause of efflorescence on the surface of products made of geopolymer materials [+ and Na+, then hydrolysis of aluminosilicate compounds, destruction of the depolymerized glassy structure, and splitting of Si and Al compounds into unstable monomeric structures [In the hardening geopolymer compositions, spatial aluminosilicate structures with the empirical formula M {-(Si-O)z-Al-O}n·w·Haterials . Accordiaterials  the dissructures . Accordiructures , the geoructures . Researcructures  proposedructures , are sho2O3 nanoparticles activated with alkaline hydroxide occurs through surface phase separation without passing through the induction period inherent in binders with such an activator [The synthesis of geopolymer materials based on aluminosilicate raw materials with a high content of Alctivator . At the Work  based on3−Na+.At the first stage in − to silicon atoms, as a result of which the valence of electrons increases to a five-covalent state.At the second stage in At the third stage in At the fourth stage in +, resulting in the formation of simple  Si-O-Na bonds.At the fifth stage in At the sixth stage when NaOH is used as an activator as in At the seventh stage in The mechanism of chemical reactions that take place during structure formation is the basis for the study of geopolymer materials, in particular, their properties, structure formation features, types of alkaline binders and mixture formulations. In conjunction with the fact that the scope of geopolymer concretes, their structure and properties depend on the Si/Al ratio ,61, undeWhen considering geopolymer concrete as an alternative to concrete with a binder in the form of OPC, it is necessary to consider the properties not only of fully cured concrete but also of the ready-to-lay mixture. Fresh mix properties include workability, setting time, shrinkage and structural changes during the setting process. It is important to note that the process of polymerization of geopolymer compositions is exothermic, so the temperature released by geopolymer concrete during hydration is also an important parameter. The properties of fully cured concrete include CS, axial TS, flexural TS, and modulus of elasticity ,142.The workability of geopolymer concretes depends on the concentration of the activator in relation to the main components of the geopolymer composition. It can also be increased by increasing the amount of water in relation to the binder or by adding superplasticizers and hardening retarders. The workability of geopolymer concretes also deteriorated with increasing NaOH concentration ,144. FigThe hardening time of geopolymer concretes depends on the concentration of NaOH, the proportion of silicates to hydroxides, the composition of the binder, and the content of superplasticizers in the mixture. Increasing the concentration of NaOH reduces the hardening time by accelerating the process of polymerization of geopolymer compositions. However, the short hardening time of the composition significantly worsens its workability ,146.Shrinkage during the hardening of geopolymer concrete significantly affects the process of formation of shrinkage cracks in it. Geopolymer concretes have greater shrinkage than OPC based concretes due to the greater number of mesopores than OPC. Geopolymer concretes shrink more than OPC-based concretes due to the fact that the alkali-activated binder itself has much greater shrinkage than OPC, and also due to the greater number of mesopores than OPC. Reducing the number of micropores and shrinkage of geopolymer concrete is possible by selecting the optimal amount of activator, the proportion of silicates to hydroxides and activator to binder, as well as by controlling the hardening conditions. It is also important to note that there is a wide range of different raw materials and types of activators for geopolymer concretes, which under different hardening conditions have quite different structural changes during hardening . The polThe process of polymerization of geopolymer concretes is exothermic and is associated with a significant release of heat in the process of hydration of the mixture components. The polymerization process, which occurs during the interaction of aluminosilicates with alkaline activators, occurs more intensively than the hydration process of OPC, as a result of which the heat released by geopolymer compositions during hardening is higher. The heat released by geopolymer concretes during the hardening process largely depends on the type of activator used and the type of feedstock. It has been established that hydroxide activators significantly increase the temperature released during the hardening process of the geopolymer composition . The typThe strength characteristics of hardened and hardened geopolymer concrete are determined by its components and their granulometric composition . The CS 2SiO3/NaOH ratio, the CS of geopolymer concrete based on slag increased, while an increase in the proportion of activator to binder led to a decrease in CS.According to , it can The weak point of concrete based on OPC is the low TS relative to the CS. Studies of geopolymer concrete have shown that its TS during thermal hardening is similar to the TS of concrete on OPC and that the dependence of the TS of geopolymer concrete on its CS is similar to that of concrete with OPC as a binder . The TS The modulus of elasticity of geopolymer concretes with the same strength is lower than that of concretes based on OPC. Presumably, this is associated with the processes occurring during the polymerization of geopolymer concretes and with their aluminosilicate base . The elaThe main factors that ensure the durability of geopolymer concrete, as well as other building materials, is its ability to withstand atmospheric influences, the chemical effects of aggressive environments, abrasion and other types of wearing effects. The durability of geopolymer concretes is determined by their properties such as sorption capacity, saturated water absorption, approximate volume of open pores, permeability for chloride and sulfate ions, as well as other acids . CompareThe properties of geopolymer concretes are determined by a number of characteristics of their raw materials ,176. TheDespite the variety of binders for geopolymer concretes, many of their characteristics are determined by the activator, in the alkaline environment in which the aluminosilicate polymerization reaction will take place. The main characteristics of the activator are its type and molarity, that is, the concentration of the activating mortar. When interacting with different types of binders, activating mortars can affect the properties of geopolymer concrete in different ways. Thus, an increase in the concentration of the activating sodium hydroxide mortar when mixed with alkali-activated slag increased the CS of the final composition, since an increase in the activity of the alkaline medium led to the formation of a large amount of products involved in the hydration reaction . IncreasAs mentioned earlier in The proportion of its main components—an activating alkaline mortar and aluminosilicate binder—has a significant impact on the strength of geopolymer concretes. The alkaline environment of the activator is necessary for the dissolution of silica and alumina contained in the binder, which subsequently form a spatial polymer structure that determines the strength properties of the final material. As a rule, an increase in the amount of activator in relation to the binder leads to a proportional decrease in the strength of the final material . MoreoveResearchers  revealed2 or CH and silic acid H4SiO4, forms calcium silicate hydrate. Thus, in the process of hydration of geopolymer concrete with partial replacement of OPC with aluminosilicate binder, hydration of aluminosilicates, hydration of Portland cement and the pozzolanic reaction of calcium hydroxide with aluminosilicates occur [Despite the outstanding qualities of geopolymer concrete with the complete replacement of OPC with aluminosilicate binders, geopolymer concrete with a partial replacement of Portland cement with aluminosilicates is very popular. The peculiarity of such concrete is that in the process of hydration, an aluminosilicate binder first enters into the reaction, which, when interacting with water, forms a film of positively charged calcium ions, which prevents the further course of the reaction. However, calcium hydroxide, formed during the hydration of the constituents of OPC, raises the pH level, which destroys the calcium ion film . At the es occur . At the es occur ,82. SummThe addition of OPC somewhat improves the microstructure of geopolymer concrete. This is due to the coexistence of hydration products and polycondensation products. Such changes in the microstructure of composites lead to a decrease in water absorption, porosity, sorption and chloride permeability of geopolymer concrete. In general, the addition of OPC makes the microstructure more compact and denser, in which the interfacial bonding of the fibers with the matrix is better .According to , it was The environmental friendliness of geopolymer concrete compared to concrete on OPC, as well as its outstanding physical and mechanical characteristics, determine the growing popularity of this material in construction. The replacement of concrete based on OPC with geopolymer concrete based on aluminosilicate binders is consistent with the concept of sustainable development. Technologies for the use of geopolymer concretes are being actively explored to reduce energy costs and greenhouse gas emissions. However, geopolymer concrete is a promising material for the construction industry also in terms of its strength properties, outstanding resistance to abrasion, aggressive environments and high temperatures . In receThe assessment of the impact of a particular technology on global warming is usually conducted using the GWP  coefficient. It provides an assessment of the degree of impact of various greenhouse gases on global warming over a certain period of time in comparison with the standard, which is taken as carbon dioxide, whose GWP is equal to 1. When assessing the global warming potential of a greenhouse gas, the number of years after the release, during which the gas exists in the atmosphere is calculated. The technology for the production of geopolymer concretes can reduce greenhouse gas emissions by up to 64% compared to the technology for the production of concrete using OPC. However, differences in the impact on greenhouse gas emissions between different types of geopolymer concretes are not so significant [2 emissions than geopolymer concretes based on metakaolin, since metakaolin requires a large amount of silicates for the polymerization reaction [It has now been established that the production of geopolymer concrete has a significantly lower global warming potential than the production of OPC . It has reaction . Howeverreaction . 2 emissions was only 9% less than concrete on OPC [It is important to note that the global warming potential is a very relative factor when it comes to the use of a material such as geopolymer concrete. This relativity is due to the fact that different calculation methods consider different types of activities associated with the use of geopolymer concrete. It was found that when taking into account all activities and energy processes associated with the production and use of geopolymer concrete, from the selection of raw materials to the placement of the finished mixture in the formwork, taking into account the transport of raw materials, the amount of COe on OPC .In recent years, 3D printing technology has gained sharp popularity due to the high speed of the production process, and the accuracy of execution, automation and manufacturability; 3D printing in one form or another is used in almost all areas of activity, going beyond global production and firmly entrenched in ordinary everyday tasks. However, the aerospace, automotive, aircraft and construction industries have become pioneers in the use of this technology. In construction, 3D printing technology provides not only the freedom to implement design mortars, but also the automation of construction processes, the reduction in waste, the consumption of raw materials and energy, and the absence of the need for highly paid labor . The abo3D printing technology using geopolymer concrete implies certain mixture characteristics suitable for automated paving, as well as the use of superplasticizers. A number of studies have been devoted to determining the optimal proportions of mixtures based on various types of binders for use in 3D printing technology. Compositions with a binder based on GGBS, FA and microsilica were studied. The influence of the content of the activator in relation to the binder and the proportion of water to the binder were investigated. The best strength characteristics were obtained at a water-to-binder proportion of 0.33 and an activator amount of 8% of the binder volume . The addThe spatial polymeric aluminosilicate structure of geopolymer concretes provides their outstanding physical and mechanical characteristics compared to concrete based on OPC, which together with the environmental friendliness of geopolymer concretes, makes them one of the main alternatives to traditional concrete . The typIn recent years, the interest of researchers has been attracted by the effect of nanomodification of geopolymer concretes based on various types of aluminosilicate binders with graphene oxide using 3D printing technology .The development of smart materials is one of the main directions for the development of new technologies in the construction industry which allow continuous diagnostics and analysis of the state of building structures without their destruction. With regard to geopolymer concretes, at the moment in scientific publications, topics related to the piezo-resistant behavior of geopolymer concretes under various deformations and the development of technologies that allow using this factor for the continuous monitoring of the state of building structures are gaining popularity. The authors of  carried 2 in laboratory conditions. Four electrodes were installed in each section, measuring the deformation and temperature of the concrete base with an accuracy of 1 μm and 0.2 °C, respectively. The research results showed the possibility of using a robotic method of applying self-sensitive geopolymers for further analysis and monitoring of the concrete state of building structures.The work  is devotIn recent years, one of the most interesting areas in the field of building materials is the creation of self-healing materials for building structures. Of particular interest to researchers is the development of technologies for self-healing concrete. For example, researchers  consider3H5O2)2) and various types of bacteria that can simply be added to the mixture or located in special microcapsules that will open when cracks form. When cracks occur, the bacteria come out of their dormant state and, with the help of certain enzymes, produce a precipitate of CaCO3, which seals the cracks in the concrete up to a certain opening width. Relatively recent studies [By analogy with ordinary concrete, the above technology can also be applied to geopolymer concrete, despite the concentrated alkaline environment in which the geopolymerization reaction takes place. According to , some of studies ,206 haveAs an alternative method for creating self-healing materials, a number of studies have proposed the use of hollow fibers that are located in the body of the material of construction, by analogy with arteries in a living organism. Hollow fibers may contain several material components, which, when released during interaction with each other or with air, seal the crack initiation site ,208. AddAlthough the above methods for creating self-healing materials are applicable to both conventional concrete and geopolymer concretes, the latter are known for significantly higher resistance to high temperatures, which opens up additional possibilities. Thus, researchers  proposedGeopolymer concrete, as mentioned earlier, is more environmentally friendly than conventional concrete due to its low carbon footprint. Self-healing concrete technologies can enhance these properties of geopolymer concrete, reducing environmental pollution by increasing the service life of geopolymer concrete structures, reducing repair costs and saving energy.In order to fully evaluate this review in terms of scientific novelty and practical significance, it is necessary to conduct a comparative analysis between the study and reviews previously performed by other authors. It is conditionally possible to divide the studies conducted by other authors, grouping them according to a number of factors. For example, part of the research was devoted to the scientometric analysis of the development of research on geopolymers, and their economic and environmental prospects ,32,52, wHowever, within the framework of such a wide and diverse topic as geopolymer concretes, for the most objective assessment of the further prospects for their development, comprehensive review studies are needed to consider promising areas in the study of these materials, taking into account their properties, features and history of research topics. Thus, in the presented work, the review of the development of research on geopolymer concretes is supported by a review of research on the microstructure and properties of these materials, their determining factors and various combinations of geopolymer mixture components. Such a framework made it possible to fully present an overview of research on current trends and innovations in the field of geopolymer concretes, which are presented not as a separate narrow topic, but as part of a global picture of research on these materials.Prospects for further research are seen in obtaining new knowledge and developing theoretical ideas about the most relevant and priority areas for the use of geopolymer concretes.(1)Geopolymer concrete is a suitable, environmentally friendly and sustainable alternative to concrete based on OPC with higher strength, physical-mechanical and deformation properties due to its more stable and denser aluminosilicate spatial microstructure. With the active use of agricultural and industrial waste, the production of geopolymer concrete can also become more economical than the production of OPC.(2)The main factors influencing the properties of fresh and hardened geopolymer concrete mixture are identified and visually presented. The physical and mechanical properties and durability of geopolymer concretes depend on the composition of the mixture and the proportions of its components. The selection of compositions must necessarily consider the main ratios of the components that determine the physical and mechanical properties of the finished material. These include activator-to-binder ratio, silicates to hydroxides, binder type, activator concentration, aggregate fineness modulus, presence and amount of superplasticizers, water-to-binder ratio, and binder-to-sand ratio.(3)Despite a large number of types of aluminosilicate binders, most researchers have considered geopolymer concretes based on FA and GGBS because of their higher strength characteristics and outstanding physical and mechanical properties compared to other types of binders. Microsilica, metakaolin, perfluorooctanoic acid, high calcium ash and rice straw ash have been considered by researchers as independent binders much less often, but their influence as additives has often been analyzed. The most popular activator mortars used by researchers are sodium hydroxide and sodium metasilicate, as well as their combinations in various ratios. Moreover, sodium metasilicate showed a faster course of the polymerization reaction compared to sodium hydroxide. The course of the polymerization reaction, in addition to the type of binder used, is greatly influenced by the characteristics of the activator, such as its concentration, amount in relation to the binder and reactivity. The optimal value of the proportion of activator to binder allows you to get the best mechanical properties and durability.(4)Geopolymer concretes with partial replacement of OPC with aluminosilicate binder have a denser and more compact microstructure due to the formation of a large amount of calcium silicate hydrate, which provides improved CS, durability, less shrinkage, porosity and water absorption.(5)2SiO3, the proportion of activator to binder, the proportion of NaOH to slag, the combined use of various activating compositions, various variations in conditions and curing temperatures, the concentration of activators, various types of coarse filler, the addition of nanomodifiers, the percentage of reinforcement, adding various additives, fibers and coarse aggregates from recycled waste to find the optimal mixture parameters and a combination of various factors to obtain the best properties of the final material. Recent research uses new ideas and technologies, such as 3D printing of fiber-reinforced geopolymer concrete, and needs to be further developed in studies based on the analysis of the properties of compositions obtained with various types of binders and activators.The first studies devoted to the subject of geopolymer concretes were aimed at obtaining new data on the influence of the ratios of the mixture components on the strength and physical-mechanical properties of the final material. They were based on the influence of such factors as the proportion of NaOH/Na(6)The technologies of the combined selection of the composition of geopolymer concrete, production of nanomodified geopolymer concrete, 3D printing of building structures from geopolymer concrete, and monitoring the state of structures using self-sensitive geopolymer concrete are considered.(7)An assessment was made of the potential reduction in greenhouse gas emissions from the production of geopolymer concrete compared to the production of OPC.(8)The inclusion of nanomodifiers, such as graphene oxide, in the composition of geopolymer concretes reduces the hardening time of the composition and increases the stability of the microstructure of the material, improving its physical and mechanical properties and positively affecting durability.(9)The most promising areas for further research of geopolymer concretes are the search for new types of aluminosilicate binders and activators; the analysis of the economic and environmental efficiency of geopolymer concretes; the development of methods for the optimal selection of compositions; the analysis of the effect of nanomodification of the composition of geopolymer concrete on the characteristics of the finished material; the search for new technologies that allow more efficient and productive 3D printing using geopolymer concretes; the search for new technologies to improve the properties of geopolymer concretes by nanomodifying the composition with graphene oxide and the search for alternative, more effective nanomodifiers; the search for technologies that can reduce the toxicity of certain types of geopolymer concretes for fresh reservoirs and humans; the search for new technologies and replacement methods concrete on OPC with geopolymer concrete and the search for new methods for monitoring the state of structures using self-sensing concrete. Self-healing concrete technologies can enhance the properties of geopolymer concrete, reduce environmental pollution by increasing the service life of geopolymer concrete structures, and reduce repair costs and save energy.The literature review presented in this article covers a wide range of research in the field of geopolymer concretes carried out in recent years. Based on the information provided, the following main conclusions can be drawn:As a result, a review of studies on modern trends and innovations in the field of geopolymer concretes was made, which was presented not as a separate narrow topic, but as part of a global picture of research on these materials. Prospects for further research are seen in obtaining new knowledge and developing theoretical ideas about the most relevant and priority areas for the use of geopolymer concretes.


Whether neoadjuvant therapy confers a survival benefit in advanced prostate cancer (PCa) remains uncertain. The primary endpoints of previous retrospective and phase II clinical studies that used neoadjuvant therapy, including androgen deprivation therapy combined with new-generation androgen receptor signaling inhibitors or chemotherapy, were pathological downstaging, progression-free survival, prostate-specific antigen relief, and local symptom improvement. To the best of our knowledge, no studies have explored the efficacy and safety of neoadjuvant therapy in improving the surgical resection rate in cases of unresectable primary tumors of PCa. We first designed this retrospective study to evaluate the potential value of apalutamide as neoadjuvant therapy in improving the resectability rate of radical prostatectomy (RP). We initially reported 7 patients with unresectable primary lesions who underwent neoadjuvant apalutamide treatment for a median of 4 months, and all of them successfully underwent RP treatment. Our study supported apalutamide as neoadjuvant therapy, which helped improve RP’s success rate and did not significantly increase perioperative complications, and the neoadjuvant therapy was controllable. Our findings’ clinical value and benefit for survival still need further clinical research to confirm. The main goals of neoadjuvant therapy for prostate cancer (PCa) based on androgen deprivation therapy (ADT) are to reduce tumor size, reduce the rate of positive surgical margins, and achieve pathological remission, but no benefit has been observed in terms of cancer-related death . Thus, nThere is no phase Ⅲ clinical study data to prove the value of survival benefit in neoadjuvant therapy for progressive PCa. Several phase II clinical studies of ARSI and chemotherapy as neoadjuvant therapy, including docetaxel  or cabazWe included PCa patients diagnosed and treated by the Fujian Prostate Disease Diagnosis and Treatment Alliance  from January 2021 to August 2023. Patients were screened according to the following inclusion and exclusion criteria. The inclusion criteria were as followings: (a) the patient was diagnosed with advanced prostate acinar adenocarcinoma (T4N0-1M0-1); (b) their physical status score were 0 according to Eastern Cooperative Oncology Group (ECOG) ; (c) the2 (range 21.7–26.3 kg/m2). Their median initial PSA was 70.12 ng/mL (range 17.34–271.58 ng/mL), and their median needle biopsy Gleason score was 9 points (range 8–10 points). Their newly diagnosed stage was cT4N0-1M0-1b. Their median ADT plus apalutamide treatment duration was 4 months (range 3–12 months). Preoperative PSA was less than 0.01–4.09 ng/mL. After neoadjuvant treatment, these patients were all re-evaluated as prostate resectable, and all underwent RP or cytoreductive proctectomy  investigating neoadjuvant apalutamide monotherapy and RP in newly diagnosed intermediate- and high-risk PCa patients, cancer burden reduction and PSA relief were obtained without any pathologic complete response . NeoadjuAlthough whether ADT combined with ARSI as neoadjuvant therapy can bring survival benefits is worthy of further research, it is relatively sure that ADT alone before RP is not recommended, especially for patients with intermediate- and low-risk PCa, as ADT can cause side effects such as weight gain and mood changes, and increases the risk of cardiovascular disease, diabetes, and osteoporosis, guidelines also strongly recommend that men who choose surgery should not undergo ADT . HoweverEvaluating which patients are suitable for RP after neoadjuvant therapy is also worth exploring. Recently, it was found that the response of prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/CT to primary PCa lesions after neoadjuvant therapy could predict the pathological response, which might be helpful for the selection of patients to perform RP. In a phase II clinical trial of high-risk PCa patients receiving ADT plus docetaxel or ADT plus abiraterone as neoadjuvant therapy, with a median follow-up time of 30 months, the study found that [68 Ga] PSMA PET/CT was an ideal tool for monitoring response to neoadjuvant therapy . After aHow to choose follow-up therapy after neoadjuvant therapy with RP is also an uncertain issue . An advaAs an exploratory retrospective study with a small sample size, this study has some limitations specific to retrospective studies. In the future, case-control studies with a large sample size are needed to evaluate this study’s conclusions further. It was important to note that the patients we selected had unresectable PCa. The definition of unresectable PCa was subjective, and whether it was resectable had a close relationship with the surgeon’s surgical skills. However, our cases were all evaluated by MRI, which objectively confirmed that PCa had progressed and invaded the rectum, bladder, or surrounding tissues. In addition, our case was based on two experienced surgeons who had undergone more than 100 PCa cases, suggesting these two surgeons were already qualified in RP. After a median of 4 months of neoadjuvant therapy with apalutamide, these patients underwent MRI re-examinations, the prostate was resectable was re-evaluated, and the potential benefits of RP through MDT were also discussed to maintain as much as possible the safety of RP and the reduction of surgical complications. Furthermore, although our study had a median follow-up time of 13 months (range 9–25 months), this follow-up time was far from enough to observe patients with PCa to determine whether apalutamide as a neoadjuvant treatment brought benefit in progression-free survival, overall survival, or its long-term side effects. However, for the purpose of our research, neoadjuvant treatment with apalutamide could help transform these selective PCa patients from unresectable primary lesions to resectable primary lesions. This was the paramount significance of this preliminary study.To the best of our knowledge, we have performed the first preliminary assessment of unresectable progressive prostate cancer; those after neoadjuvant apalutamide therapy were converted to resectable prostate cancer, with no significant increase in perioperative complications and a tolerable safety of the neoadjuvant therapy. Our study provides a new opportunity for RP therapy in progressive prostate cancer. Further clinical studies still need to confirm whether this treatment brings survival benefits to patients.


Nocardiosis is an opportunistic infection in immunocompromised individuals, particularly patients with acquired immune deficiency syndrome (AIDS). Clinical manifestations of nocardiosis are wide-ranging but the most common is pneumonia.Nocardia species infected adult patients (≥15 years) with at least 28 days of treatment follow-up. This study aims to compare clinical manifestations and survival analysis of cultured confirmed pulmonary nocardiosis among AIDS and non-AIDS patients.This 14 year retrospective study included Nocardia species infection, of which 22 were excluded from this study because 13 had cutaneous nocardiosis and nine had pulmonary nocardiosis with follow-up less than 28 days. A total of 215 confirmed pulmonary nocardiosis were recruited to the analysis, 97(45.1%) were HIV-infected and 118 (54.9%) were non-HIV. All HIV-infected patient has CD4 count below 200 cell/mm3 , known as AIDS. Most of them were male with a mean age of 37 (range 15-83) years. One hundred fifty of the 215 (69.7%) patients underwent brain imaging. Sixteen cases (10.7%) had brain abscess. Disseminated nocardiosis  was found in equal proportions in AIDS  and non-AIDS patients , while pulmonary nocardiosis with local invasion  was more common in AIDS  than non-AIDS patients . Overall and 28 days mortality were 116 (53.9%) and 88 (40.9%), respectively. In Cox’s proportional hazard analysis, AIDS was the independent factor associated with 28 days mortality in pulmonary nocardiosis  and those who underwent brain imaging  after adjusted by sex, age, duration of illness, respiratory failure, shock, multi-lobar pneumonia, disseminated nocardiosis, and combination antibiotic therapy.From 2009 to 2022, 237 patients had culture confirmed Pulmonary nocardiosis is a serious opportunistic infection in AIDS patient and has shown significantly higher mortality than non-AIDS. Therefore, nocardiosis should always be considered as a cause of pneumonia in AIDS patients in order to prompt aggressive treatment.Yupin Suputtamongkol, MD, Abbott Labs: Grant/Research Support|Abbott Labs: Mahidol University is partner in the Abbott Pandemic Defense Coalition


Thermoplastic vulcanizates (TPVs) are multifunctional materials consisting of two or more phases with solid elastomeric properties at room temperatures and fluid-like properties above their melting point. They are produced through a reactive blending process known as dynamic vulcanization. The most widely produced TPV type is ethylene propylene diene monomer/polypropylene (EPDM/PP), which is the focus of this study. The peroxides are mainly selected to be used in crosslinking of EPDM/PP-based TPV. However, they still have some disadvantages, such as the side reactions resulting in the beta chain scission of the PP phase and undesired disproportionation reactions. To eliminate these disadvantages, coagents are used. In this study, for the first time, the use of vinyl functionalized polyhedral oligomeric silsesquioxane (OV-POSS) nanoparticles was investigated as a potential coagent in EPDM/PP-based TPV production via peroxide-initiated dynamic vulcanization. The properties of the TPVs having POSS were compared with the conventional TPVs containing conventional coagents, such as triallyl cyanurate (TAC). POSS content and EPDM/PP ratio were investigated as the material parameters. Mechanical properties of EPDM/PP TPVs exhibited higher values in the presence of OV-POSS, which resulted from the active participation of OV-POSS into the three-dimensional network structure of EPDM/PP during dynamic vulcanization. Thermoplastic vulcanizates (TPVs) are multifunctional polymeric materials classified as thermoplastic elastomers. TPV materials comprise a large amount of crosslinked elastomer as a dispersed phase and a small amount of continuous thermoplastic matrix ,2. ThereThe most widely used crosslinking agents for EPDM/PP TPVs are peroxides and phenolic resins ,20,21. DCoagents are used to eliminate these disadvantages in the presence of peroxides ,23,24,25Polyhedral oligomeric silsesquioxanes (POSSs) are structurally lattice-shaped molecules. It can be called polyhedral skeletons formed by silicon and oxygen with closed formulas (RSiO1.5). Here, “n” is greater than four and is often 8. The R group in the structure can consist of many different functional groups . Since POSSs are 1.5 nm in size and have an average molecular weight of 1000 Da, they are almost similar in size to many polymer molecules. Recent studies show that different types of POSS molecules have been used as co-plasticizer, nucleating agents, adhesion promoters, non-flammability additives, compatibilizers, modification agents, antibacterial agents, anti-proliferative agents, etc. ,44,45,46POSS structures containing vinyl or acrylic groups can turn into very reactive coagents in the presence of peroxides. Therefore, it can increase crosslinking efficiency of peroxide-containing TPV systems. Blanco and Zaharescu prepared EPDM/POSS composites and subjected them to γ-irradiation. They stated that the POSS cage restricted the chain mobility of EPDM . In a reIn this study, an octavinyl functionalized POSS (OV-POSS) was utilized as a coagent for the first time in a TPV system. The vinyl groups on the nanocage of OV-POSS would make it involved in the crosslinking reaction as a coagent and simultaneously improve the strength of the resulting TPV at a molecular level due to the molecular stiffness of the POSS cage. Dynamic vulcanization in the presence of peroxide was carried out in a laboratory micro-compounder . The content of OV-POSS as a coagent, peroxide content, and EPDM/PP ratio was taken as the material parameters. The crosslinking density, compression set, tensile properties, morphology, and rheology of the TPVs were investigated. The performance of nascent TPV was compared with that of conventional TPVs.® and Irgafos®) were purchased from Hybrid Plastics and BASF, respectively.The materials used in the study are shown in TPVs were prepared via melt blending in a vertically positioned twin-screw batch micro-compounder having a recirculation channel  . The barThe coagent/DCP ratio was taken as 1, 3, 5, and 7. The samples were abbreviated with respect to the type and loading level of the coagent, such as 70/30 EPDM/PP/Coagent(X) . Here, XAn Anton Paar Modular Compact Rheometer, MCR 102, with plate-plate geometry of 25 mm diameter, was used to conduct the rheological tests. Frequency sweep measurements were carried out at 175 °C under a nitrogen atmosphere at a shear strain of 1% and an angular frequency range between 0.1 and 600 rad/s.The tensile properties were measured with an Instron Universal Testing Machine (Model 3345) according to ISO37 with type 2 sample geometry. The crosshead speed was 500 mm/min. Tensile strength, elongation at break, and 100% modulus values of TPVs were obtained from stress–strain graphs.Compression set determination of the samples was conducted according to ASTM D395 with method B and type 2 geometry. The hardness of the samples was measured according to ASTM D2240 using a Zwick Shore-type durometer.Ʋe + PP. The latter was done to avoid the need to correct for a part of the PP being extracted as amorphous PP [c” is the average molecular weight between the crosslinked points (g/mol), “ρ” is the density of samples (g/cm3), “V0” is the molar volume of the solvent (for cyclohexane is 108.7 cm3/mol), “ꭕ” is polymer-swelling agent interaction parameter, or Flory–Huggins parameter, which in this case is 0.315 [0” is the initial mass of the sample (g), “Ws” is the mass of the swollen sample (g), and “ρ1” and “ρ” are the density of the cyclohexane and EPDM (g/cm3), respectively. Sample densities were measured with the Mettler Toledo density kit according to the Archimedes principle.The overall crosslink density (CLD) of the EPDM phase in EPDM/PP TPVs was determined based on solvent-swelling measurements in cyclohexane at 25 °C according to the Flory–Rehner method (Equation (1)). Samples were submerged in acetone, then cyclohexane. After 24 h, the swollen sample was weighed, dried, and weighed again. From the degree of swelling, an overall CLD was calculated relative to the EPDM + PP phases as expressed by phous PP ,56,57. can be calculated from Equation (3) using the final (mf) and initial (mi) weights of the specimen.The surface morphologies of the TPVs were examined by the QUANTA 400F Field Emission model scanning electron microscope (SEM) to determine the phase sizes and interfacial interactions of the samples. The samples were cryogenically broken for SEM analysis, and the fracture surfaces were sputter-coated with gold. Moreover, the surface morphology of TPVs was also evaluated by atomic force microscopy  in dynamic force mode. A microtome was used to prepare ultrathin sections for AFM analyses.The variation of complex viscosity (η*), storage (G′), and loss (G″) modulus concerning the EPDM/PP ratio and content of the TAC and OV-POSS as the coagent are shown in All the complex viscosity values (η*) decreased with increasing frequency (ω), indicating the shear-thinning behavior of the pseudoplastic liquid due to the deformation of the entanglement of the chains at high frequencies. The neat-PP exhibited a plateau region at low shear rates, where complex viscosity is slightly influenced by the increasing frequency, followed by a decreasing viscosity region at high shear rates due to the alignment of the molecules a. SimilaIt is known that the TPV’s morphology and structure influence the rheological behavior. The viscoelastic properties of a binary polymer blend system depend on the dispersed phase’s deformability and shape/size. Moreover, the deformability is also related to the size of the dispersed component. The elastic and viscous characteristics of the TPVs are well reflected by the change of G′ and G″ with angular frequency. Generally, at low frequencies, the G′ value provides information about the long-range relaxation (beyond entanglement distance). In contrast, the corresponding value at high frequency relies on short-range relaxation (motion with entanglement) . Figure In a TPV system, the mechanical properties are associated with the rubber/plastic ratio, the crosslink density of the rubber phase, the size and distribution of the rubber phase, the thickness of the plastic ligaments, and the compatibility of the plastic and rubber phases ,64,65,66The mechanical properties of nano-sized particle-reinforced polymer composites, such as POSS nanoparticle-containing polymer composites, depend highly on particle size, particle-matrix interfacial adhesion, and particle loading ratio . Rigid iThe representative stress–strain curves of selected TPVs are given in The variation in the mechanical properties of the samples, such as elongation at break, 100% modulus, tensile strength, compression set, and hardness with respect to the composition, is given in When the hardness values of EPDM/PP/Coagent(X) TPVs are examined, a similar trend was observed with the tensile strength and 100% modulus values, especially when OV-POSS was used as the coagent. This was due to the improvement in crosslink density of the EPDM/PP system in the presence of OV-POSS .The variation in the compression set values of TPVs with respect to coagent type and coagaent/DCP ratios are shown in In this section, the mechanical properties of the samples aged at 70 °C for 70 h were evaluated by compression tests. The mass change of samples measured after the swelling test at 125 °C in IRM 903 standard oil for 70 h is given in The effectiveness of the coagents used to increase the crosslinking efficiency can also be seen from the SEM pictures. As 7 phr TAC was added to the 70/30 EPDM/PP + DCP system, the average size of the dispersed EPDM particles decreased significantly and were homogeneously dispersed in the PP matrix. Additionally, the most notable result here is that the large spherical particles (circled in the SEM images) observed with the addition of DCP to the 30/70 EPDM/PP system are no longer visible. This indicates that the chain scission reactions occurring in the PP phase in the presence of DCP radicals are suppressed by the addition of TAC into the structure. For EPDM/PP TPVs having 7 phr OV-POSS coagent, almost a single-phase morphological structure was determined regardless of the mixing ratio. These findings show that the dispersed phase particle sizes decreased significantly depending on the composition of TPV in the presence of OV-POSS, indicating that OV-POSS is an effective coagent for PP/EPDM system.Two- and three-dimensional phase-topography AFM images of the samples are shown in When the AFM images of dynamically cured TPVs were examined, phase inversion in 70/30 EPDM/PP after vulcanization was observed. After phase inversion, the continuous EPDM phase turned into the dispersed phase and dispersed more homogeneously in the PP phase, resulting from EPDM’s crosslinking during dynamic vulcanization. It is clearly seen that the phase separation observed before dynamic curing is not present in EPDM/PP/Coagent(3) systems. This was because the chain scission reactions occurring in PP were partially prevented in the presence of a coagent, and hence, the cross-linked EPDM particles were finely dispersed. The smallest dispersed particle sizes in EPDM/PP system were obtained in the presence of OV-POSS in AFM pictures, which is another indication of the effectiveness of OV-POSS as a coagent for EPDM/PP vulcanizates.In this study, the potential use of POSS nanocages having vinyl bonds was investigated as a coagent in EPDM/PP-based TPV production via dynamic vulcanization for the first time in the literature. The properties of the TPVs having POSS were compared with the TPVs produced using conventional coagents of TAC. The motivation for using POSS to prepare TPV was the potential of having increased crosslink density due to high functionality per POSS molecule and the limited segregation of the EPDM particles during dynamic vulcanization in the presence of POSS. In addition, once the OV-POSS forms the crosslink bridges between the constituents, then a self-reinforcing effect at a molecular level could be realized due to the stiff cage structure of POSS.Rheological analyses showed that EPDM/PP TPVs, including OV-POSS as a coagent, exhibited higher complex viscosity values. The relaxation was suppressed, and the elasticity of the TPV became more dominant in the presence of OV-POSS. Mechanical test results revealed that the tensile strength and 100% modulus of EPDM/PP TPVs, including OV-POSS, was higher than that of EPDM/PP TPVs with TAC due to the higher crosslinking density in the presence of OV-POSS. SEM and AFM analysis showed that dispersed phase particle sizes decreased significantly depending on the mixing ratio and coagent type. In general, OV-POSS nanoparticles with unsaturated double bonds were found to be effective coagents for EPDM/PP systems compared to conventional coagents.


An estimated 25% of U.S. nursing home residents may have an antibiotic resistant infection. Antibiotic resistance is primarily driven by antibiotic use, thus, increasing our understanding of trends in antibiotic use within nursing homes is needed to address this public health threat. Our study examined changes in antibiotic prescriptions among nursing home residents using claims data from January 2018 through December 2020.Linked files from Medicare Part D and the Minimum Dataset 3.0 covering years 2018-2020 were used to describe antibiotic use in U.S. nursing homes via nationwide trend analysis. Over two million adults, aged 65 years and older, who were covered by Medicare Part D for the entire duration of their stay were included. Changes in trends by antibiotic class and U.S. region were also assessed.The majority of antibiotics prescribed in U.S. nursing homes were administered by the oral route (98%), and cephalosporins were the most prescribed class of antibiotics (38.6%). The overall proportion of orally administered antibiotics prescribed across U.S. nursing homes increased from January 2018 through December 2020 by 2.6%. There were 155 DOT/1000 patient days in 2018, 166 in 2019, and an increase to 269 in 2020 for oral antibiotics. Intravenous (IV) antibiotic prescribing increased by 71% during this time but only accounted for 2% of all antibiotic prescriptions. There was 1 DOT/1000 patient days in 2018 and 2019 and 3 DOT/1000 patient days in 2020 for IV antibiotics. Variations in prescribing were seen by U.S. region, with the largest increase in oral antibiotics in the West (4.6% increase); and by antibiotic class, with increases in the use of carbapenems (82%), cephalosporins (11.3%), oxazolidinones (70.1%), and Daptomycin (65.3%). All changes were statistically significant at the 0.05 cutoff level.From 2018 through 2019, antibiotic prescribing rates remained relatively unchanged in U.S. nursing homes. However, there were differences by antibiotic class and U.S. region. There was a large increase in the use of both oral and IV antibiotics in 2020, most likely due to confounding factors introduced by the COVID-19 pandemic.All Authors: No reported disclosures


Currently, mass concrete is increasingly utilized in various engineering projects that demand high physical properties of concrete. The water-cement ratio of mass concrete is comparatively smaller than that of the concrete used in dam engineering. However, the occurrence of severe cracking in mass concrete has been reported in numerous engineering applications. To address this issue, the incorporation of MgO expansive agent (MEA) in concrete has been widely recognized as an effective method to prevent mass concrete from cracking. In this research, three distinct temperature conditions were established based on the temperature elevation of mass concrete in practical engineering scenarios. To replicate the temperature increase under operational conditions, a device was fabricated that employed a stainless-steel barrel as the container for concrete, which was enveloped with insulation cotton for thermal insulation purposes. Three different MEA dosages were used during the pouring of concrete, and sine strain gauges were placed within the concrete to gauge the resulting strain. The hydration level of MEA was studied using thermogravimetric analysis (TG) to calculate the degree of hydration. The findings demonstrate that temperature has a significant impact on the performance of MEA; a higher temperature results in more complete hydration of MEA. The design of the three temperature conditions revealed that when the peak temperature exceeded 60 °C in two cases, the addition of 6% MEA was sufficient to fully compensate for the early shrinkage of concrete. Moreover, in instances where the peak temperature exceeded 60 °C, the impact of temperature on accelerating MEA hydration was more noticeable. The utilization of mass concrete has become increasingly prevalent in various civil engineering projects such as high-rise buildings, tunnels, and box girders, due to the upsurge in demand for such projects. Concrete is a fragile material with a lower tensile strength compared to its compressive strength, and mass concrete possesses the attributes of high total heat release and a large volume. The substantial size of the concrete impedes the timely dissipation of the heat generated from hydration, causing a rapid and considerable temperature increase in the mass concrete, with a significant temperature differential between the interior and exterior. Previously, dams utilized concrete with a high water-cement ratio and a relatively small amount of cement, leading to low heat of cement hydration and internal temperatures below 50 °C. However, in contemporary large-scale projects like retaining walls and bearing platforms, the utilization of mass concrete necessitates a smaller water-cement ratio, resulting in high heat of hydration and central temperatures above 70 °C, generating tensile stress that surpasses the concrete’s tensile limit, ultimately leading to cracking ,2.3 content in cement on the dry shrinkage of concrete demonstrated that the dry shrinkage of concrete reduces as the SO3 content increases, as long as it does not surpass 3.1%. On the other hand, if it exceeds 3.1%, the trend is reversed [In the context of mass concrete with a low water-cement ratio, autogenous shrinkage is a crucial factor that contributes to cracking. In engineering, autogenous shrinkage is particularly pronounced in high-strength concrete, self-consolidating concrete, and mass concrete. Research indicates that high-strength concrete with a water-cement ratio of less than 0.3 can experience an autogenous shrinkage of 300–400 με and that the magnitude of autogenous shrinkage increases with the amount of cement per unit volume . Similarreversed . Currentreversed ,10,11. IExpansive agents are commonly utilized in dam engineering to counteract the notable shrinkage of mass concrete and to forestall cracking. The MgO expansive agent (MEA) is a particularly promising candidate due to its superior expansion performance and the adjustability of its expansion behavior ,13. In rGiven the high temperature sensitivity of both MEA and cement, investigating the impact of temperature on the deformation of MEA concrete is a crucial endeavor. There have been several investigations concerning the impact of curing temperature on the performance of MEA concrete. However, these studies were carried out mostly under conditions of high water-cement ratios and constant curing temperatures, which are inconsistent with the conditions encountered in large-scale vertical walls and load-bearing platforms where the temperature of the concrete can significantly increase due to the heat of hydration. Such engineering projects often require the use of a large number of cementitious materials and a relatively high water-cement ratio for dam concrete to achieve high concrete strength. Consequently, the central temperature of the concrete may reach over 70 °C, and the temperature is not constant. The use of constant temperature conditions in studying MEA concrete does not reflect the actual conditions encountered in engineering projects. To address this limitation, this study employs an insulation tool that can simulate the temperature change process of concrete under working conditions. By incorporating temperature and sine-type strain gauges into the concrete and monitoring the temperature and strain development of the concrete, the study aims to simulate the concrete strain in engineering structures and investigate the deformation performance of MEA concrete under different engineering temperatures.In this study, ordinary Portland cement  manufactured by Onoda Cement in Nanjing, China was employed. Fly ash (FA) was procured locally in Nanjing, China, while granulated blast furnace slag powder, designated as S95 mineral powder, was provided by Jiangsu Huailong Building Materials Co, Nanjing, China. The fine aggregate (fineness modulus of 2.7) had a well-graded size distribution and a well-rounded shape. Three types of coarse aggregate with the size grading of large size stone (20–25 mm), middle size stone (10–20 mm), and small size stone (5–10 mm) were used in the ratio of 2:5:3. The MEA used in the study was supplied by Jiangsu Subot, Nanjing, China, and was tested to have reaction values of 300 s using the citric acid method. The chemical composition, particle size, and specific surface area of the various adhesive materials used are presented in This study aimed to develop tools that could simulate working conditions’ temperatures. The tools consisted of a stainless-steel barrel used as a container for the concrete, which was wrapped with insulation cotton around its exterior. The tool’s ability to simulate various temperature changes was achieved by adjusting the volume of the concrete and the thickness of the insulation layer and by selecting different insulation materials. Three tools were selected from the fabricated tools to match the actual temperature rise curve of the poured concrete. The simulation tools are visually represented in To ensure that the simulation tools can effectively mimic the actual engineering structures, this study referred to the temperature-rise curve of a large thin-wall structure in a real project. The wall has a total length of 24 m, a height of 3.4 m, and a thickness of 1.1 m. The temperature rise was measured by using built-in strain gauges at the center, surface, and bottom of the wall, and the temperature rise of the wall is shown in Based on the Chinese standard GB/T 50081-2019 , followiTemperature and Autogenous deformation of concrete at early ages were measured by using the tools described in To evaluate the hydration extent of MgO, the thermogravimetric technique was employed on HPC mixtures lacking aggregate at the 3 d and 7 d stages in accordance with the Chinese standard GB/T 22314-2008 . FollowiTo examine the microstructure of cement hydration products containing MEA, small portions of the cement pastes were sectioned, soaked in anhydrous ethanol for a minimum of 24 h to stop the hydration, and subsequently dried at 60 °C for 24 h. The resulting samples were then coated with gold and visualized using the Hitachi Regulus 8100 scanning electron microscope.It is worth noting that the decline in strength observed at temperature C is relatively less pronounced compared to temperatures A and B, which could be attributed to the swift hydration of cement at high temperatures, which offsets the deleterious effects of MEA on the compressive strength of concrete.2, Ca(OH)2, and CaCO3, respectively. The degree of hydration of Mg(OH)2 and MgO(H MgO) was calculated using Equations (2) and (3), respectively, according to the literature [2 represents the content of Mg(OH)2 formed in the hydrated cement pastes; the n represents the amounts of MEA in cement paste.terature ,34.(2)M2 and the extent of MgO hydration in cement paste that incorporates MEA. It can be observed that the addition of MEA results in an increase in the content of Mg(OH)2 in the samples, and a higher dosage of MEA corresponds to a greater degree of MgO hydration. For instance, under temperature condition A, the degree of MgO hydration after seven days was 32.41% and 38.19% when 8% and 10% of MEA were added to the cement, respectively. By comparing the degree of MgO hydration at three different temperature conditions, it can be inferred that the extent of MgO hydration escalates with an increase in the curing temperature. When the MEA concentration is 8%, the degree of MgO hydration at temperatures A, B, and C are 32.41%, 65.71%, and 84.34%, respectively. When the MEA concentration is 10%, the degree of MgO hydration at temperatures A, B, and C are 38.19%, 74.98%, and 84.40%, respectively. Evidently, higher curing temperatures facilitate the hydration of MgO. The degree of MEA hydration at temperature A is only 30%, whereas, at temperature B, it surpasses 60%. After seven days of hydration at temperature C, the degree of MEA hydration is around 80%. This implies that MEA hydrates expeditiously when the temperature exceeds 60 °C, and the rate of hydration does not increase proportionally with the temperature. The enhancing effect is relatively feeble before 60 °C.2, which initiates at the surface of MEA particles and then progresses toward the center, is the primary product of this hydration process. An analysis of the figures indicates that the quantity of MEA hydration products increases with higher curing temperatures. For instance, in 2 is limited, and its observation is challenging. Conversely, 2 densely spread on the surface of spherical particles. Additionally, The impact of temperature on the performance of MEA is of great significance. The addition of MEA to concrete under temperature conditions B and C results in a larger expansion value compared to temperature condition A, which has a lower temperature peak. In temperature condition A, the early autogenous shrinkage of concrete cannot be fully compensated by the addition of 6% of MEA, while the addition of 8% of MEA only barely compensates for it. On the other hand, adding 6% of MEA at temperatures B and C leads to a significant expansion of the concrete. While the addition of 6%, 8%, and 10% of MEA does not differ much in expansion value at temperature A, there is a significant difference in expansion value at temperatures B and C with the addition of different amounts of MEA. Based on the thermogravimetry (TG) analysis, it is evident that the hydration of MEA is more complete at higher temperatures, which explains why the expansion of the concrete under temperature condition C is larger than under temperature conditions B and A. At temperature condition A, the hydration degree of MEA is only 30%, while at temperature condition B, the hydration degree of MEA has already reached over 60%. After 7 days of hydration at temperature condition C, the hydration degree of MEA is about 80%. This indicates that the hydration of MEA is rapid at temperatures above 60 °C, and the promoting effect is relatively weak before 60 °C, with the hydration rate not proportional to the temperature increase.The effects of three different temperature conditions on the mechanical properties, autogenous shrinkage, and microstructure of high-strength concrete with MEA were studied. The main conclusions are as follows:This investigation examined the impact of MEA incorporation on concrete’s compressive strength under different temperature conditions. The results demonstrate that the addition of MEA to concrete at different levels results in a decrease in compressive strength, and this reduction becomes more significant with increased MEA content. Notably, the decline in compressive strength at a higher temperature C is less pronounced than that observed in temperatures A and B. This outcome is attributed to the rapid hydration of cement at high temperatures, which offsets the detrimental effects of MEA on the compressive strength of concrete. This suggests that adding a higher amount of MEA could be considered in engineering processes where higher temperatures are involved.In comparison to temperature condition A, which exhibits a lower temperature peak value, the use of MEA in concrete mixtures under temperature conditions B and C resulted in significantly greater expansion values. Under temperature condition A, the addition of 6% MEA failed to fully offset early autogenous shrinkage in the concrete. When 6% of MEA was used in mixtures under temperature conditions B and C, significant expansion was observed. While mixtures containing 6%, 8%, and 10% of MEA exhibited minimal differences in expansion values under temperature condition A, there were substantial differences in expansion values observed under temperature conditions B and C for mixtures containing varying amounts of MEA. In previous construction projects, the addition of 8% MEA has been a common approach to mitigate the impact of shrinkage on concrete stability. However, this study suggests that a lower concentration of 6% MEA is sufficient to compensate for the shrinkage in two out of three tested temperature conditions. Therefore, it may be worthwhile to reduce the amount of MEA in order to maintain the stability and strength of concrete.MEA hydration is more complete at elevated temperatures, which accounts for the greater expansion of concrete at temperature C compared to temperatures A and B. At temperature A, MEA achieves only 30% hydration, while at temperature B, it achieves more than 60%. The degree of hydration for MEA after 7 days at temperature C is approximately 80%. MEA undergoes rapid hydration at temperatures exceeding 60 °C, and the rate of hydration is not directly proportional to temperature. Furthermore, the enhancing effect of temperature on the hydration of MEA is relatively weak before 60 °C.This paper investigated the compressive strength and autogenous deformation of MEA concrete under three temperature conditions. However, the actual temperature rise of mass concrete in engineering applications is diverse. More temperature conditions should be studied. In addition, this study only used one type of MEA, and more types of MEA can be investigated in the future.