IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory disease whose pathogenesis has not been completely elucidated. Due to the novelty and complexity of the diagnostic criteria, it is difficult to distinguish from the diseases included in the differential diagnosis without tissue biopsy. This study aimed to discover new biomarkers that can help for disease diagnosis and its differential diagnosis by reviewing the relationships between neutrophil-lymphocyte ratio (NLR), platelet lymphocyte ratio (PLR), systemic immune-inflammation index (SII), and systemic inflammation response index (SIRI).Thirty IgG4-RD, 38 granulomatous polyangiitis (GPA), and 46 sarcoidosis patients presenting to the Rheumatology Clinic meeting the criteria of 2019 American College of Rheumatology, 2012 International Chapel Hill and 1999 American Thoracic Society meeting, respectively, and 27 healthy control subjects were included. We collected data on complete blood count with automated differential values including NLR, PLR, SII, and SIRI.The SII and PLR values were significantly higher in patients with IgG4-RD compared to healthy controls, (SII median (min-max) 572 (102–5583) vs. 434 (172–897), PLR median (min-max) 130 (56.8–546) vs. 104 (57.5–253) p < 0.001). SII value was found to have a significant positive correlation with CRP in IgG4-RD disease . While SII, SIRI, NLR, PLR parameters were not significant between the IgG4-RD and sarcoidosis groups, SII, SIRI, NLR, PLR were significantly higher in patients with GPA than in IgG4-RD patients (p < 0.001).This is the first study to review the SII, SIRI, NLR, and PLR in IgG4-RD. The obtained results suggest that the SII could be used as a new tool, for differential diagnosis and activity of the IgG4-RD. IgG4-RD is frequently detected incidentally during the histopathological or radiological examination of a tissue ,3. Diagnosis is established via combination of clinical, radiological, laboratory and pathologic characteristics of disease. Prior to the 2019 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) diagnostic criteria, there was an identification criterion based on serum IgG4 levels and histopathological IgG4/IgG+ positivity. However, it was realized that serum IgG4 levels can be found to be normal in most IgG4-RD patient subtypes such as retroperitoneal fibrosis. For this reason, the former classification criteria are no longer used . According to the newly defined criteria, even if the value of IgG4 in the patient’s serum and histopathology is negative, a total score of ≥20 after meeting the entry and exclusion criteria is enough to make the diagnosis of IgG4-RD . IgG4-RD is a disease with chronic relapses, there is currently no objective marker to predict relapse as well as diagnosis. In some studies, serum IgG4 level was examined in terms of predicting relapse, but its levels were found to be normal during relapses . In IgG4-RD, apart from the presence of serum IgG4, hypergammaglobulinemia, hyper-IgE, low titer positive antinuclear antibodies, eosinophilia, high CRP, rheumatoid factor, and hypocomplementemia can be seen in blood . However, these parameters are not specific and may increase in many other diseases as well as IgG4-RD. Compared to the serum IgG4 level, level of serum plasmablast is a more valuable biomarker in the IgG4-RD but difficulty and complexity of its measurement limits its clinical use.IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory disease, in which T cytotoxic cells and plasmablasts play a prominent role –10. GPA and IgG4-RD have been reported to overlap, sometimes presenting as GPA with atypical features, such as pachymeningitis, orbital mass, or chronic periaortitis. In patients with bilateral hilar adenopathy, the clinical picture may imitate sarcoidosis. Thus, it is important to differentiate IgG4-RD from sarcoidosis and GPA, which are frequently encountered in clinical practice. In GPA and sarcoidosis, ANCA-IFA and angiotensin converting enzyme (ACE) might help in making diagnosis ,12. Yet, these markers can also be positive in IgG4-RD. Therefore, there is still no objective marker to assess the diagnosis, differential diagnosis, and prognosis of IgG4-RD. Recently, complete blood count parameters suggested to have diagnostic and prognostic value in many inflammatory diseases . These inflammatory indices rapidly yield results since they are evaluated during routine blood count. We wanted to study simple tests, which may help in the determination of diagnosis and estimation of prognosis, such as systemic inflammatory index (SII), systemic inflammatory response index (SIRI), platelet/lymphocyte ratio (PLR), neutrophil/lymphocyte ratio (NLR) in IgG4-RD patients and, if possible, to find a cutoff value for disease.The differential diagnosis of IgG4-RD includes many diseases such as sarcoidosis and granulomatosis with polyangiitis (GPA) ,14,15. Subgroups of GPA and sarcoidosis with findings of especially pulmonary failure/haemorrhage, renal failure, and neurological involvement were excepted from the study.Thirty IgG4-RD , 38 GPA , and 46 sarcoidosis  patients presenting to the rheumatology clinic, and 27 healthy controls  were included. Of the patients with IgG4-RD, GPA and sarcoidosis, 16.6% (n = 5), 21.7% (n = 10), 21% (n = 8) were newly diagnosed. Patients with cases with isolated upper respiratory tract disease, orbital involvement, salivary gland involvement, lung and lymph node involvement were included. We excluded patients <18 years of age and those with another disease that could reason elevate SII, SIRI, NLR, and PLR values: i.e. patients with any type of malignancy, haematological diseases, serious cardiac disorder , hepatic enzyme elevations due to any cause, different chronic respiratory diseases  systemic diseases and COVID-19. Patients fulfilled the 2019 ACR for IgG4-RD, the 2012 revised International Chapel Hill Consensus Conference classification criteria for GPA, and the 1999 American Thoracic Society classification criteria for sarcoidosis . The SII is provided by calculating (thrombocyte×neutrophil)/lymphocyte; the SIRI: is provided by calculating (monocyte×neutrophil)/lymphocyte . The laboratory reference values of white blood cells, neutrophils, lymphocytes, and eosinophils were 4.2–10, 1.8–7.3, 1.5–4, and 0.05–0.35 (×) 103/uL, respectively. This study was approved by the ethics committee , conducted in accordance with the 1975 Helsinki Declaration. Written informed consents were obtained from all participants prior to enrolment into the study.Individuals were examined and evaluated by an experienced rheumatologist. Laboratory, treatment, clinical, and demographic data were collected from patients upon admission. Demographic data included age, gender, and smoking habits (current/former/ever). The smoking index was calculated with years of tobacco use × number of cigarettes smoked per day. Laboratory tests were collected from all patients upon hospitalization before the start of medications. They included; complete blood count (CBC), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). CBC with automated differential counts included neutrophils, lymphocytes, platelets, and differential values. In the control group, CBC and differential values, serum biochemical tests, ESR, and CRP were measured. Neutrophil lymphocyte ratio (NLR) was calculated as the ratio of neutrophils to lymphocytes. Platelet lymphocyte ratio (PLR) was acquired by dividing the absolute number of platelets to lymphocytes For statistical analyses, NCSS  2007  program was used. In the evaluation of data, descriptive statistical methods  were utilized. Whether quantitative data were distributed normally was evaluated with the Shapiro-Wilk test and graphics. In the comparison of more than two groups between normally distributed quantitative parameters, one-way ANOVA analysis, and Bonferroni test evaluations were made. When quantitative parameters were not normally distributed, in the comparisons between more than two groups, the Kruskal-Wallis test and Dunn’s test were used. Chi-square or Fisher’s exact tests were used to compare categorical variables. In the evaluation of the relationship between quantitative variables, Pearson’s and Spearman’s correlation tests were utilized for correlation analyses. In order to determine predictive values for parameters, diagnostic screening tests  and ROC analyses were used distinguishing IgG4 patients from healthy subjects. The optimal cutoff values for the sensitivity and specificity of SIRI, SII, NLR, and PLR in predicting IgG4-RD were calculated by using Youden’s index. The p-value of <0.05 was considered statistically significant.. The fact that SII was more diagnostic than NLR in IgG4-RD patients was attributed to the addition of platelets to this ratio. It was also found that SII, SIRI, and NLR values correlated with CRP but not with ESR in the IgG4-RD group. In conclusion, it was established that the SII value is more valuable index than others in that it predicts diagnosis and differential diagnosis and reflects disease activity more accurately. Lymphocyte values were found to be highest in the IgG4-RD group, while neutrophil value was highest in the GPA group. In GPA and sarcoidosis groups, all indices were found to be significantly higher than control group. SII cutoff values were found to be highest in GPA group, while they were similar in sarcoidosis and IgG4-RD groups. Cutoff value of all indices other than SII was found to be higher in sarcoidosis group than IgG4-RD group. Although SII by itself may be a supportive finding in discriminating GPA from IgG4-RD, other indices should also be evaluated so that they can be discriminate from sarcoidosis.As mentioned above, inflammatory cells have a varying degree of role in the pathogenesis of IgG4-RD. However, evaluating them on their yields less information than the ratio between them. Therefore, inflammation has to be considered as a whole e.g., while no difference was found between the four groups in terms of platelet counts significant differences were found between groups for PLR and SII indices. All such indices, especially NLR and PLR are practical and cost-effective prognostic markers, which have long been used in various diseases. In malignancies, they were found to be high during disease activity and, decrease when the disease went into remission. In a study carried out on COVID-19, it was established that adverse prognostic factors such as ferritin, d-dimer and eosinophilia correlated positively with NLR and PLR markers. It was seen that these indices correlated not only with laboratory markers but also with thorax CT images and it was concluded that patients with high NLR and PLR values should undergo CT examination earlier since these patients have higher rates of mortality and need more intensive care admission We believe that the use of all indices in clinical practice is effective ancillary testing for the differential diagnosis of diseases. Even though they are not used for diagnosis and predicting prognosis on their own, they may be used as a supportive method in addition to physical examination, radiological examination, and laboratory tests. In GPA, inflammatory indices have a higher correlation with sedimentation and CRP than IgG4-RD, indicating that GPA may have a more aggressive course, even if it has limited organ involvement. IgG4 disease has lower activity at the time of diagnosis than GPA or sarcoidosis and hence should not be initially considered in patients with high NLR, SII and SIRI values and in such patients GPA and subsequently, sarcoidosis should be ruled out in diagnostic process.Basic hematologic indices might help to differentiate IgG4-RD from limited GPA and sarcoidosis. Moreover, combination of these indices may be helpful the physician in the assessment of IgG4-RD disease activity. Further research is required to establish how these indices can be used in the clinical setting to improve the clinical management of IgG4-RD.There are several limitations in our study. Major drawback is its crosssectional design. We could not determine whether its levels changed with treatment and whether it may predict relapse. Maybe in the future we can determine how response levels to treatment change in IgG4-RD patients only with serial biomarker measurements.


The sustainable development of construction materials is an essential aspect of current worldwide trends. Reusing post-production waste in the building industry has numerous positive effects on the environment. Since concrete is one of the materials that people manufacture and use the most, it will continue to be an integral element of the surrounding reality. In this study, the relationship between the individual components and parameters of concrete and its compressive strength properties was assessed. In the experimental works, concrete mixes with different contents of sand, gravel, Portland cement CEM II/B-S 42.5 N, water, superplasticizer, air-entraining admixture, and fly ash from the thermal conversion of municipal sewage sludge (SSFA) were designed. According to legal requirements in the European Union, SSFA waste from the sewage sludge incineration process in a fluidized bed furnace should not be stored in landfills but processed in various ways. Unfortunately, its generated amounts are too large, so new management technologies should be sought. During the experimental work, the compressive strength of concrete samples of various classes, namely, C8/10, C12/15, C16/20, C20/25, C25/30, C30/37, and C35/45, were measured. The higher-class concrete samples that were used, the greater the compressive strength obtained, ranging from 13.7 to 55.2 MPa. A correlation analysis was carried out between the mechanical strength of waste-modified concretes and the composition of concrete mixes , as well as the water-to-cement ratio and the sand point. No negative effect of the addition of SSFA on the strength of concrete samples was demonstrated, which translates into economic and environmental benefits. China, which released 853 Mt of CO2 into the atmosphere in 2021, is the world leader in CO2 emissions into the atmosphere from cement production. India (149 MMT), Vietnam (54.1 MMT), Turkey (44.4 MMT), the United States (41.2 MMT), Saudi Arabia (28.7 MMT), Indonesia (28.6 MMT), Japan (23.8 MMT), South Korea (23.7 MMT), and Iran (22.5 MMT) are the countries that come behind it [2 emissions. Thanks to this, the landfilling of waste is reduced, which becomes a new raw material used by the construction industry in accordance with the principles of sustainable development and the circular economy [Construction-related advancements necessitate the ongoing development of building materials, particularly concrete. The competition between various construction materials is intensifying as globalization advances. In order to find and create products with the best strength and durability, there is therefore a lot of research being conducted in the area of concrete durability. Concrete is used in the construction of buildings because it is strong, durable, and has superior strength characteristics. Sand, gravel, and cement are just a few of the ingredients used to make concrete. In order to impart particular performance attributes, extra chemical admixtures are also used in the concrete mix . The Uninesia 28. MMT, Japrabia 28. MMT, Ind India 14 MMT, Vie economy .2 emissions into the atmosphere [Fly ash (FA) and waste glass sludge are two of the industrial wastes that are most commonly utilized to produce concrete. Landfilling the waste causes significant environmental issues, such as the tainting of ground or surface waters, an increase in soil alkalinity, and detrimental impacts on vegetation and other living organisms. Thus, using waste materials has environmental benefits by reducing landfilling and lowering COmosphere ,11,12. Fmosphere .Fly ash (FA), a by-product of combustion operations, is one of the useful waste materials added to concrete mixtures. The fine-grained dust, which is made up of grains of erratic sizes and shapes, is a useful mineral additive. FA increases the workability of concrete mixes, but it also makes concrete more resistant to the aggressive sulfate environment, slows down the hardening process, makes concrete more resistant to high temperatures (up to 600 °C), reduces frost resistance, reduces shrinkage, and makes hardened concrete stronger and more durable. The adroit application of FA’s features results in concrete with improved properties that are suited to receivers’ requirements. An additional benefit is the reduced price of concrete compared to that made using only cement. A further advantage is that the concrete costs are less than those of concrete produced only with cement. Numerous researchers have discussed in the literature the impact of adding different forms of FA on the characteristics of concrete ,17,18,19x, CO2, and other pollutants. Public education or a greater understanding of the advantages of waste recycling may be an additional benefit. The usage of the SSFA additive has benefits as well as drawbacks, such as its decreased pozzolanic activity, which results in a reduction in strength qualities and an increase in water consumption, although these drawbacks can be offset by grinding, appropriate modification, and treatment. Another limitation is the lower reactivity of these materials compared to cement flour [Numerous financial and environmental advantages come from adding SSFA to cement and concrete. These include removing sewage sludge to free up space in landfills that already exist, cutting costs and raising the quality of many building materials, lowering waste disposal costs, including those associated with landfilling, lowering the use of a significant amount of primary raw materials, implementing a sustainable development economy system by turning sewage sludge waste into new useful products, conserving energy, and lowering the emissions of NOnt flour ,33,34,35There are reports of laboratory attempts to utilize SSFA waste for use in regular concrete and cement mortars in the literature. However, the findings of this research are unclear and do not suggest that they might be implemented in the manufacturing of regular concrete products. Therefore, a study was undertaken to determine compressive strength, one of the most crucial parameters for modified concrete. SSFA may be used as an addition in the creation of concrete mixes in line with the applicable Polish legislation   and the The aim of the research was to determine the influence of SSFA waste generated during the combustion process of municipal sewage sludge in a fluidized bed furnace on the compressive strength of different classes of concrete. The correlation of the mechanical strength of waste-modified concretes with respect to the composition of concrete mixes , water-to-cement ratio, and sand point was analyzed.The use of fly ash as a waste product from the incineration of local municipal sewage sludge utilizing modern circulating fluidized bed combustion (CFBC) technology is the scientific novelty of the research. Using this technology to thermally treat sewage sludge has a number of advantages, including a sizable decrease in waste weight, the recovery of thermal energy during combustion, high process efficiency, low pollutant emissions, the reduction of odors, system stability, and low susceptibility to changes in sludge composition. SSFA may be added to concrete, bricks, asphalt, ceramics, or other materials in addition to serving as a filter medium. It has a high content of mineral substances, and its quality and composition depend on the chemical composition of the sludge, the conditions of the combustion process, flue gas cleaning, and the cooling rate. According to the new regulations in the European Union, landfilling of waste should be avoided, and methods of safe and ecological disposal are to be sought. In Poland, the problem is the excessive amount of sewage sludge produced; hence, more and more thermal processing installations are being built. These activities are in line with the trends of sustainable development and the circular economy. Hence, this research work is a response to regional problems in Poland related to waste management and brings suggestions that may be a partial solution to these problems. In Central Europe, the construction industry is a booming sector that can partially absorb excess SSFA and convert it into new building materials.The present studies in this manuscript are limited to the compressive strength of concrete and the analysis of correlations with individual components. The limitation also applies to a period of up to 28 days. Because compressive strength is a feature that serves one of the most crucial roles in concrete structures, tensile and flexural strength tests were left out. Because the experiments were concentrated on the strength characteristics of the concrete samples, other tests, such as durability evaluations, were not conducted.The elemental composition of SSFA samples was examined with a scanning electron microscope (SEM) Hitachi S-3700N  with an attached Noran SIX energy dispersive X-ray spectrometer (EDS) microanalyzer (ultra-dry silicon drift type with resolution (FWHM) 129 eV, accelerating voltage: 20.0 kV; manufacturer: Thermo Electron Corporation, Schönwalde-Glien, Germany).High-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM) were carried out using a JEOLARM 200F (accuracy: the highest point resolution is around 0.05 nm). SSFA samples for analysis using transmission electron microscopy were prepared by deposition of catalysts onto holey carbon films supported by a copper TEM grid.Cu Kα1 = 1.5406 Å) and a LynxEye silicon strip detector. The minimum measurement angle is 0.6° 2Θ deg. The XRD powder diffraction method requires the delivered sample to be carefully powderized. A standard measuring dish has a container for powder with a diameter of 25 mm and a depth of 1.5 mm. Before measurement, the sample powder needs to be lightly pressed.X-ray diffraction measurements were made using the D8 Advance diffractometer . In configuration, the diffractometer is equipped with a Johansson monochromator , F is the maximum force at the point of failure (N), and A is the cross-sectional surface area (m2).Compressive strength tests were conducted using an Ele International Automatic Compression Machine  that meets the requirements of the PN-EN 12390-4:2020-03 standard . The samThe correctness of the test performance was determined using the schemes of correct and incorrect destruction of samples defined in the European Standard SIST EN 12390-2:2009 .The investigation was conducted using seven different types of recipes for concrete mixtures of various strengths. 3 content ≤ 3.5%, Cl content ≤ 0.1%, initial setting time ≥ 60 min, change in volume ≤ 10 mm, compressive strength after 2 days ≥ 10 MPa, compressive strength after 28 days between 42.5 and 62.5 MPa, Na2Oeq content ≤ 0.8%.The first digit indicates the type of cement; in this case, each recipe starts with 5, which means that Portland slag cement CEM II/B-S 42.5 N was used. Requirements of the cement are as follows: SOThe next two digits indicate the class of concrete, e.g., 10 means class C8/10.The digit 4 repeated in each of the concrete recipes indicates that aggregate with grain sizes up to 16 mm was used for research.The last two digits are successive numbers assigned as a result of creating a recipe.The following ingredients were used to make samples of concrete mixes:○Sand, 0/2 mm ;○Gravel, 2/8 mm and 8/16 mm ;○CEM II/B-S 42.5 N cement , symbol designation: CEM II—multi-component Portland cement, 42.5—compressive strength class after 28 days determined in accordance with the Polish standard PN-EN 196-1, S—granulated blast furnace slag, N—normal early strength cement;○Water from municipal water supplies;○Fly ash waste produced as a by-product of the combustion of municipal sewage sludge;○Sikament 400/30  plasticizer;○LPS A94 (Sika Poland Sp. zo.o.) air-entraining admixture.The recipe number is the designation of the concrete composition, which determines the class of concrete and is characterized by a certain strength. Each digit in the recipe number has a specific meaning:The physico-chemical properties of 0/2 sand and 2/8 and 8/16 gravel are shown in 2/g, specific gravity 2.91 kg/dm3, initial setting time 240 min, 2-day compressive strength 22.3 MPa, 28-day compressive strength 56.4 MPa.The chemical composition of CEM II/B-S 42.5 N was determined using the X-ray Diffraction (XRD) method, and the results are presented in Sikament 400/30 superplasticizer is a homogeneous dark brown liquid consisting of sulfonated and non-sulfonated polycondensates of sodium and magnesium salts and carbohydrates . Sikament 400/30 has the following characteristics: density of 1.1 kg/m3, pH of 5.0 ± 1.0, chloride ion content ≤0.1%, and sodium oxide equivalent ≤4.0%. The superplasticizer admixture’s activity in concrete mixtures is based on the electrostatic repulsion principle. This enables the concrete mix and concrete to have the following properties: intensive wetting of the cement grains by forming a double ionic layer; a significant reduction in friction force; the ability to reduce the amount of mixing water or to liquefy the mix with a constant amount of mixing water; an improvement in workability; the facilitation of the achievement of high water tightness, frost resistance, and reduced water absorption; longer consistency retention; and high durability.® Luftporenbildner LPS A-94 air-entraining admixture  is a homogeneous dark brown liquid consisting of modified tensides. The properties are the following: density of 1 kg/dm3, pH of 7.0 ± 1.0, chloride ion content ≤0.1%, and sodium oxide equivalent ≤0.6%. The process by which the additive in concrete mixes works is based on the production of extremely small air bubbles in the cement grout. Correct pore size and arrangement, increased workability due to air entrainment, and high levels of frost resistance in water and salt solutions are all made possible by this process.The Sika2) at a temperature of approx. 800–900 °C. Up to 95% of pollutants can be blocked from entering the atmosphere thanks to this solution. Grain fractions are reported in 3. On a vibrating table, the fly ash was further compressed to a density of 1.52 ± 0.03 g/cm3. The outcomes of these investigations are crucial for the potential addition of fly ash to building materials. SEM-EDS analysis revealed that it was primarily comprised of SiO2, Al2O3, P2O5, CaO, CO2, Fe2O3, K2O, and other substances  using circulating fluidized bed combustion (CFBC) technology. This technology uses a recirculating loop, i.e., air is blown through a bed of sand at a speed sufficient to suspend particles on the air stream (approx. 1–3 m/sbstances . The facST is setting time (min), e is exponential number, and CaO is CaO content in fly ash .The literature reports that the amount of CaO in the mixture affects the setting time. Fly ash is appropriate for concrete mixes when the CaO level is between 5% and 15%, according to Diaz et al. . It was According to the formula, the predicted setting time of a concrete mix with a CaO content of 10.2% in SSFA is 333.4 min.Compressive strength was measured on six cubic samples: C8/10, C12/15, C16/20, C20/25, C25/30, C30/37, and C35/45. The compressive strength of concrete is a parameter determining its durability, and the appropriate selection of its class allows it to be used in a building structure exposed to specific external influences. All test results, including sample weight, density, destructive force at maximum sample load, and compressive strength , are preAccording to the results in 3 of concrete; however, it should not exceed 400 kg. The cement content proves the durability of concrete to the extent that it affects the water-to-cement (w/c) ratio. The relationship between the amount of cement and SSFA used and the compressive strength of concrete is presented in The relationship between the class of concrete samples and their compressive strength is shown in It demonstrates that the correct amount of cement should be used to produce the right class of concrete in order to achieve a strength greater than the one that is guaranteed. According to these experiments, increasing the cement addition led to an increase in compressive strength. The addition of SSFA did not weaken the strength properties of concrete, so it can be successfully used. Other researchers who conducted research on the addition of FA published findings that were comparable ,17,18,19One of the most crucial factors affecting the strength of properly compacted concrete is the w/c ratio. When water is added to concrete mixtures to promote fluidity, the w/c value rises, and the strength of the concrete is compromised. As a result, it is advised to aim for low w/c ratios in order to produce concrete that is both strong and of high quality. The correlation between the water-to-cement ratio (w/c) and the compressive strength of concrete is depicted in The compressive strength of concrete was shown to increase as the class of concrete increased while keeping the appropriate composition of components (from 13.7 MPa (C8/10) to 55.2 MPa (C35/45)).Concrete mixes with low w/c ratios and high cement contents showed increases in compressive strength compared to mixes with high w/c ratios and low cement contents.The addition of SSFA as a by-product of municipal sewage sludge incineration did not reduce the compressive strength, so it can be successively used. There are no legal regulations regarding the requirements for the physical and chemical properties of SSFA from the combustion of municipal sewage sludge, and there are also no legal specifications regarding the possibility of their use in the production of concrete. Oxides of calcium, phosphorus, aluminum, silicon, and iron had the highest concentrations in SSFA samples. Utilizing the waste materials lowers the price of making concrete and prevents it from going to landfills.According to these investigations, compressive strength increased when sand content decreased (from 990 kg to 620 kg) and sand point value decreased (from 0.54% to 0.32%). On the other hand, the compressive strength increased as the amount of 2/8 gravel (from 360 kg to 562) and 8/16 gravel (from 468 kg to 670 kg) increased.These investigations allowed us to show the relationship between the mechanical strength of waste-modified concretes and various parameters, including the composition of concrete mixes , water-to-cement (w/c) ratio, and sand point. Current Polish and European regulations allow the use of fly ash obtained from the combustion of sewage sludge as an additive for the preparation of concrete mixes ,37. TherThe results of the experimentation revealed how specific components and parameters affected the compressive strength of concrete samples. The components of the concrete mixes and their mutual ratios should be selected in such a way that the execution of the concrete is as economical as possible while maintaining the minimal standards of quality, in particular, strength, durability, and consistency. The experimental outcomes supported the hypothesis that the thermal transformation of municipal sewage sludge into fly ash using CFBC technology improved the strength characteristics of concrete. The offered findings serve as the foundation for further study in this field. Further research on the influence of composition variability on the technical parameters of concretes containing fly ash from sewage sludge seems necessary, as does a correlation analysis between these variables and the strength properties of concrete samples.


Concrete hosts a small but diverse microbiome that changes over time. Shotgun metagenomic sequencing would enable assessment of both the diversity and function of the microbial community in concrete, but a number of unique challenges make this difficult for concrete samples. The high concentration of divalent cations in concrete interferes with nucleic acid extraction, and the extremely low biomass in concrete means that DNA from laboratory contamination may be a large fraction of the sequence data. Here, we develop an improved method for DNA extraction from concrete, with higher yield and lower laboratory contamination. To show that this method provides DNA of sufficient quality and quantity to do shotgun metagenomic sequencing, DNA was extracted from a sample of concrete obtained from a road bridge and sequenced with an Illumina MiSeq system. This microbial community was dominated by halophilic Bacteria and Archaea, with enriched functional pathways related to osmotic stress responses. Although this was a pilot-scale effort, we demonstrate that metagenomic sequencing can be used to characterize microbial communities in concrete and that older concrete structures may host different microbes than recently poured concrete.IMPORTANCE Prior work on the microbial communities of concrete focused on the surfaces of concrete structures such as sewage pipes or bridge pilings, where thick biofilms were easy to observe and sample. Because the biomass inside concrete is so low, more recent analyses of the microbial communities inside concrete used amplicon sequencing methods to describe those communities. However, to understand the activity and physiology of microbes in concrete, or to develop living infrastructure, we must develop more direct methods of community analysis. The method developed here for DNA extraction and metagenomic sequencing can be used for analysis of microbial communities inside concrete and can likely be adapted for other cementitious materials. Concrete is a dry, salty, oxidized, alkaline environment that hosts a small but diverse community of microbes , 2. It iThe surface of concrete is somewhat more welcoming to microbes than the inside, since it is exposed to ambient conditions where nutrients are more available and the pH and dryness can be moderated. In fact, microbial biofilms on concrete have been well studied in sewer systems –11, brid–12–16–Shotgun metagenomics is more useful than amplicon sequencing for obtaining information about microbial communities’ metabolic capabilities. However, concrete has such low biomass that metagenomic sequencing poses a real challenge: contaminating DNA from the laboratory and reagents often comprises a relatively large fraction of the extracted DNA and, therefore, a large number of the sequences obtained. We extracted DNA from road, bridge, and foundation concrete samples from Delaware and New Jersey, as well as from concrete cylinders described in reference Here, we report an improved method for extracting DNA from concrete samples, adapted from ancient DNA methods , 20, whiSeveral modifications to our DNA extraction protocol were evaluated for their ability to increase DNA yield while limiting background contamination. We previously extracted DNA from concrete samples with a chloroform-based protocol modified from one designed for DNA extraction from ancient bone , 21. TheThe Qiagen PowerMax DNA extraction kit was also used to extract DNA from concrete, with and without modifications. In addition to the standard kit protocol, we tested washing the concrete with EDTA prior to lysis, adding lysozyme and proteinase K to the lysis buffer from reference Many challenges of extracting DNA from concrete are shared with extracting DNA from ancient bone and tooth samples, and the ancient DNA field more generally , 20, 23.Illumina MiSeq sequencing generated 1,240,164 raw read pairs from the DNA extracted from concrete; no reads were obtained from the negative-control extraction. After adapter trimming and quality filtering, 1,237,961 read pairs remained. The GC content of reads was 61%. The average sequence length before trimming was 154 bp; after trimming, the average read lengths were 151 bp (forward) or 150 bp (reverse). Reads were assembled with metaSPAdes (Reads were first classified with Kraken 2 against the Genome Taxonomy Database (GTDB), successfully classifying 767,469 reads  as either Bacteria (48.8%) or Archaea (12.8%). Reads unclassified against GTDB  were further classified with Kraken 2 against a RefSeq database including eukaryotes (0.46%) and viruses (0.0036%).Proteobacteria (42%), Actinobacteria (24%), Firmicutes (Bacillota) (7.6%), and Bacteroidota (2%) , which includes Halomonas, the most abundant genus observed (9%), Marinobacter (1.3%), and Salinisphaera (2.3%). Alphaproteobacteria were also abundant (17%), particularly Rhodobacteraceae (6.4%), Methylobacterium (2.5%), Rhizobiaceae (2.4%), and Sphingomonadaceae (1.2%). The phylum Actinobacteriota represented 24% of the community, with most belonging to the class Actinomycetia (19%). In the actinobacterial class Rubrobacteria, the genus Rubrobacter (3.5%) was also abundant. Firmicutes (Bacillota) were 7.7% of the community, particularly the genera Marinococcus (4.9%) and Halobacillus (0.96%).Considering the relative abundance of organisms , the majority of organisms observed were Bacteria (78.6%), specifically ota (2%) . GammaprHalobacteria (20.5%), were abundant in this community and included the species with the highest relative abundance, Halogranum rubrum  and Halalkalicoccus (1.2%).Archaea (20.6%), almost exclusively from um 4.4%; . The genColletotrichum and Fusarium. A separate community analysis using the lowest common ancestor (LCA) of reads mapped to the UniRef100 protein databases also confirmed low fungal abundance (0.76%) . The viral sequences observed were mostly bacteriophage of Mycobacterium, Gordonia, Rhizobium, or Acinetobacter.Eukaryotes (0.73%) and viruses (0.0051%) represented only small proportions of the classified reads. The most abundant eukaryotic groups included plants  and fungi (0.045%). Most metazoan reads (0.12%) were human , likely contamination, while fungi were mostly the plant pathogens Halobacteria were enriched, including gas vesicle formation  terms in the concrete metagenomic data relative to all GO annotations of the UniRef90 database was determined by mapping UniRef90 clusters to GO terms and testing for .enrichment with the topGO R package  Table 2Table 2 Sormation . CompletEctoine and hydroxyectoine are compatible solutes produced by Bacteria and Archaea in high-salt environments , 33, 34.Halogranum and Halalkalicoccus). Homologs of EctCD (the ectoine and hydroxyectoine synthases) were observed in contigs originating from both Bacillota and Actinobacteria. The Gammaproteobacteria appear to encode all four (hydroxy)ectoine biosynthetic genes, the ectoine transporter, and all of the necessary genes for degradation of ectoine ectoine biosynthesis genes, only EctB was observed in contigs from Archaea  and Marinococcus halophilus . Genes involved in anaerobic processes were also observed among the top hits of reads mapped to UniRef100 gene clusters, including fermentation , dissimilatory nitrate reduction (nitrate reductase), and denitrification (nitrous-oxide reductase) (Table S4).Oxygen availability may vary through the concrete matrix, so the predicted oxygen usage and tolerance of community members was profiled by (i) comparison to annotations in the BacDive microbial phenotype database, (ii) computational trait prediction for reference genomes most similar to community members identified with sourmash, and (iii) the presence of key genes from anaerobic processes. Genera with BacDive annotations accounted for 51.42% of the community abundance, and the vast majority were predicted to be aerobes (49.5%), although some putative facultative anaerobes (0.5%) and obligate anaerobes (0.3%) were also identified. Genomic trait predictions were similar; Traitar predicted oxygen sensitivity traits for 10 of the 15 reference genomes. Seven were predicted to be aerobes, two were predicted to be facultative anaerobes, and one was predicted to be capnophilic. Two of the more abundant predicted obligate anaerobes were both N-acetyl-d-glucosamine synthesis N-glycosyltransferase pgaC genes from Halomonas utahensis and Pseudomonas indica were 96.8%  and 90.7%  covered by reads, respectively. Reads also mapped to a pgaB N-deacetylase gene from Halomonas . Genes involved in other biofilm-related processes were also observed from Marinococcus luteus , Oxalobacteraceae bacterium OM1 , and Nesterenkonia spp.  (Table S5).Because biofilms were observed on the surfaces of some concrete pieces , the potential for biofilm formation was assessed using read mapping to UniRef100 gene clusters involved in biofilm formation. Biofilm polysaccharide poly-β-1,6-Here, we analyzed DNA extracted from an 81-year-old, alkali-silica reaction (ASR)-affected concrete bridge in New Jersey and found a microbial community dominated by halophiles, with a large number of halophilic Archaea, and very few eukaryotes. These microbes encode pathways that potentially allow them to mitigate the primary selective pressures in concrete, including heavy metal tolerance, biofilm formation, and a variety of osmotic stress responses. This contrasts with our previous work in much younger concrete (<3 years old), which used 16S amplicon sequencing to characterize a microbial community composed primarily of generalist, sometimes oligotrophic, Bacteria and no detectable Archaea  environment. As concrete ages and reacts with COes to ~9 . Furtheres to ~9 . This daes to ~9 . This stalbaceae , 39.Halobacteria, so it is unknown whether Archaea were not observed due to primer specificity or absence/low abundance in the samples.The differences between the microbial community in this aged, damaged structure and those in young (less than 3 years old) concrete suggests that the microbial communities may change over time. The large number of reads attributable to Archaea (~30%) were a surprise, since no Archaea were detected in any of the samples in our previous work. The primers used in our previous study (357F/806R) do not amplify 16S genes from Halomonas and Halobacillus spp. were observed in freshwater and soil microbial communities impacted by deicing salts . To avoid damaging the structure, the sample was collected from a large piece of concrete that had broken off from the underside of the bridge deck. A roughly 500-cmTo increase the DNA yield and decrease contamination introduced during DNA extraction, we tested a number of modifications to the protocol (see File S1). After development of the modified protocol, DNA was extracted from 10 g of ground concrete from a New Jersey bridge and a blank negative control extraction. After grinding, all materials were handled inside a UV- and bleach-decontaminated PCR hood. DNA was quantified using an Invitrogen Qubit fluorometer (version 2) with a Qubit dsDNA high-sensitivity (HS) assay kit .−1; New England Biolabs, no. P8107S), 138 μL 20% SDS, and 0.2 mL acetic acid in a 50-mL conical tube, scaled up from methods previously described  and 125 μL of a silica suspension prepared as previously described  Quality control. Reads were filtered and trimmed with TrimGalore version 6.6 (https://github.com/MarescaLab/concrete_metagenome_test). Software dependencies in the workflow ere managed by Conda and Docker to aid reproducibility.sion 6.6 . FastQC sion 6.6  was usedsion 6.6 . Human rsion 6.6  via Covesion 6.6  (paramet(ii) Taxonomic analysis. The k-mer-based tool Kraken 2 version 2.1.1 (ftp.tue.mpg.de/ebio/projects/struo/GTDB_release95/. Reads from Eukarya and viruses were classified against a precomputed RefSeq database (PlusPFP 1/27/2021) available at https://benlangmead.github.io/aws-indexes/k2. From Kraken 2 taxonomic profiles, Bracken  Assembly. Reads were assembled with metaSPAdes (taSPAdes  version (iv) Functional analysis. General functional annotation was performed with the HUMAnN3 tool (http://ftp.tue.mpg.de/ebio/projects/struo2/) and taxonomic annotations produced with Kraken 2 and Bracken . Additionally, traits including oxygen tolerance were predicted using a python3 implementation of Traitar  Statistical analysis. Enrichment of biological process GO terms was calculated with the topGO R package, using the default weight01 method, which assigns greater weight to more specific GO terms (GO terms , 68.PRJNA846790.Raw and assembled DNA sequences are available at the NCBI, associated with BioProject


This study characterizes the transmittance behavior of structural light-transmitting concrete under natural sunlight. The experimentation involves the use of a novel test setup and a detailed analysis considering the variation and dependence on time of day, month of the year and seasonal variations. The test set consisted of 28 variations of fiber configurations, with two different diameters, spacing and bundling techniques used to increase the area of fibers while maintaining spacing to aid the placing of concrete without compromising on transmittance. The study provides a real-time observational understanding of the behavior of light-transmitting concrete, a result usually obtained by modelling and simulation. The statistical analysis helps in understanding the impact of various variables as well as their interrelationships, which can help in design optimization. Based on the behavior as well as the stipulations of standards, the applicability of the material to various structural applications has been identified. The evolution of concrete has given rise to innovative designs that transcend mere aesthetics and serve both functional and ecological purposes. Once confined to its role as a load-bearing material, concrete has transformed into a specialized substance with distinct properties, encompassing setting, hardening and durability. This adaptability, attained through meticulous molecular-level modifications, has elevated concrete to one of the most prevalent and reliable construction materials globally. As the world increasingly embraces environmental consciousness and sustainability, the imperative to develop environmentally friendly construction materials and processes that safeguard energy and the ecosystem has grown exponentially.A noteworthy endeavor in this direction is the advent of light-transmitting concrete, ingeniously harnessing sunlight to curtail energy consumption for illumination while elevating the visual allure of structures. This groundbreaking concept, popularly known as LiTraCon, originated in the early 2000s through the visionary craftsmanship of Hungarian architect Aron Losonczi. Pioneering researchers have tirelessly explored an array of materials and chemicals to achieve translucency in concrete panels, using polymeric and siliceous optic fibers as key components and inventing construction materials that are both energy efficient and aesthetically captivating. Optic fibers have been embedded in concrete, in combination with other fibers such as glass, in order to enhance the flexural properties of concrete. The use of glass fibers enhances the split tensile and flexural strength of concrete with unidirectional optic fibers . The incAmidst the backdrop of a global energy crisis, scholars have fervently pursued renewable energy alternatives to supplant finite resources. For instance, the surge in total energy consumption has been considerable in India, with a substantial share devoted to illuminating residential, commercial and industrial sectors . Light-tNumerous research endeavors have been dedicated to developing cementitious materials that facilitate light transmission. Researchers have established correlations between the area of fibers and light transmittance, encompassing various fiber volume fractions and diameters. Materials like waste glass, resin, optical fibers, translucent powders and other materials have been used as transmitting members in light-transmitting concrete with their own advantages and limitations . The infSimulation studies have been diligently executed to appraise the performance of light-transmitting concrete when subjected to natural light conditions. A simulation of the daylighting performance of translucent concrete building envelopes has elucidated how the fibers with larger numerical apertures, like 0.7, compared to smaller ones, like 0.5, can enhance average luminance flux up to 40.62% . A numerWhile having a database on these characteristics, the present research scenario lacks information regarding real-time data on the material exposed to natural light. The volatile nature of the atmosphere and weather means modelling and simulation produce similar results but ignore outliers that might not necessarily conform to modelling conditions.This comprehensive study aspires to elucidate the behavior of light-transmitting concrete under natural light conditions, encompassing the intricate interplay of environmental factors on light transmittance. The research delves into the influence of diurnal variations, seasonal dynamics, monthly fluctuations and annual trends on transmittance characteristics. In addition, the study endeavors to identify the most appropriate applications of diverse variants per the stipulated guidelines of Indian Standards.One of the scientific terms used in the manuscript are transmittance, which is the percentage ratio of transmitted light to incident light. The loss in transmittance is the difference between the amount of light entering and exiting the transmitting media, mainly caused due to absorption and scattering or reflection at the surface of the fiber. Illumination, or illuminance, is the amount of luminous flux per area at any point on a surface.This research focuses on exploring the possibility of using light-transmitting concrete as a structural concrete, which would be a material that would add to the list of green energy materials that are the need of the hour. The work is a detailed experimental investigation into transmittance behavior and presents the results of 1 year of data collection and subsequent analysis in order to understand the effects of factors such as time of the day and weather conditions. The data reflect how there is a variation in behavior based on weather and a detailed statistical investigation using multivariate analyses of variances sheds light on what specific factors impact certain behaviors in the concrete. Additionally, the manuscript also highlights an experimental methodology using specifically designed equipment. The interdependence of various factors on transmittance, the influence of these factors and a possible method to optimize the inclusion of fibers based on diameter, spacing and the total number of fibers used per bundle is possible and can form the base for further investigation into prototypes or durability characteristics, either of which can help in realizing the material and accelerate its integration into the infrastructure and construction industry.The concrete was produced using OPC 43 grade, well-graded river sand, coarse aggregates with a maximum grain size of 10 mm, fly ash, potable water and a superplasticizing agent. The materials were tested for quality based on the stipulation of Indian Standards. Cement conformed to IS 8112:2013 , aggregaOptical fibers of large numerical aperture and acceptance cones were selected for the study. Polymeric bare fibers with an acceptance angle 61° and a numerical aperture of 0.51 and of two diameters, namely 0.5 mm and 1 mm, were procured from M/s Edmund Optics, India. The fibers had polymeric cores made of PolyMethyleneMethAcrylate (PMMA), colloquially known as acrylic fibers. The fibers were chosen to have a large acceptance angle since the source of light was sunlight and hence highly scattered. The optic fiber was examined under an SEM to inspect and understand the nature of the longitudinal and cut surfaces. The specific gravity, tensile strength and modulus of elasticity of these fibers were 1.18, 38.36 MPa and 95.60 MPa, respectively.Scanning Electron Microscopy is an essential tool to analyze the surface morphology and size distribution of particles in concrete. The surface properties affect how the particles interact in the matrix and can give indications of the behavior of the constituents in the matrix.The SEM analysis of optical fibers was carried out to determine the cut surface properties and the surface properties. The surface impacts the bonding efficiency, with rough surfaces conducive to better bonds, whereas smoother surfaces reduce the bond strength. More irregular surfaces impart better friction and pull-out resistance as they increase the surface area available for bonding and help with interlocking. The cut surface properties are essential to the study as they can affect the transmittance properties, and the technique used to cut fibers can result in high losses in transmittance if the surface is uneven. There can also be reflective and refractive losses due to rougher surfaces. The chosen type of concrete that was suitable for the closely spaced fibers in the mold was Self-Compacting Concrete (SCC). SCC is known for its high workability and passing ability, and the closely spaced fibers behave as a highly reinforced section, thus it is the best-suited type of concrete. The design of concrete such as SCC provides flexibility and the required workability while opening options to improve fresh properties through gradation techniques while maintaining strength ,27. The The fabrication of light-transmitting concrete requires specialized molds capable of integrating fibers during the casting process. These molds play a crucial role in securing the fibers in place during casting, ensuring that their ends remain exposed to light for effective light transmittance, as illustrated in Conventional industrial casting techniques involve layering thin alternating layers of mortar and fibers using mechanical means. However, when applied to concrete, this method proves inadequate due to coarse aggregates, causing the fiber ends to become embedded within the concrete and resulting in significant light transmission loss. Researchers have adopted innovative approaches to address this limitation, such as utilizing unique molds and weaving techniques to incorporate fibers within the concrete ,31,32.In this particular study, the researchers employed perforated molds measuring 100 × 100 mm. The spacing of the perforations adhered to the guidelines specified in IS 456:2000 , which dThe casting process involved two main steps: weaving the fibers and pouring the concrete. The fibers were individually woven into the molds based on predetermined bundling sizes. After completing the fiber weaving, SCC was mixed and poured into the molds. Since SCC does not require compaction, the samples were lightly compacted using a table vibrator due to the close spacing of the fibers. The samples were then left to set and harden. Once sufficiently hardened, the ends of the fibers were trimmed and the samples were de-molded before ponding for curing. After reaching desirable strength and setting, the fiber ends were cut precisely and a hand grinder was used to achieve a smooth and uniform surface suitable for testing purposes.Optical properties were measured with specially designed equipmentThe equipment consisted of a black box with an aperture at the top to rest the cube and a mechanism to rest the receiver of the lux meter within the black box, as shown in p-value of ANOVA results indicate the level of significance based on which the null hypothesis is rejected or accepted. The null hypothesis of ANOVA is usually that the parameters have no significant impact on each other. The testing was performed based on a 95% confidence interval, based on which the p-values have been accepted or rejected, and the significance of an independent variable on a dependent variable has been determined [The transmittance results depend on multiple factors like the incorporation of fibers, the number of fibers, the area of fibers, spacing, time of the day, month, season, etc. Analysis of variance (ANOVA) was carried out to determine and validate the results obtained. ANOVA is a powerful statistical tool that helps determine the effects of independent variables on the dependent variables. It also gives a clear picture of the influence of a combination of these independent variables on the test parameters. Understanding the magnitude of the effect these parameters have and the significance of these variables on our test parameters is essential in understanding and customizing the material based on the purpose of use. ANOVA is a hypothesis testing tool where the testing is conducted to determine the effect of one parameter on another. The termined . Since tA plot of the annual illumination average vs. time of day illustrates the dependence of the time of the day on luminance. As the angle of incidence of sunlight reduces, there is an increase in the transmitted intensity of luminance. All mixes show maximum luminance at 12.30 p.m., and the midday durations exhibit higher luminance than the ends of the day.In the current study, the variable chosen for analysis is the average annual illuminance, illustrated in p-values are below 0.005.The illumination values that were obtained over the year were compiled and averaged relative to the time of measurement, which was then considered as the average annual illumination. The impact of various factors on the average annual illumination is represented in The interaction effects of Time and Diameter, Time and Spacing, Time and No. of Fibers, Diameter and Spacing, Diameter and No. of Fibers, Spacing and No. of Fibers as well as the effect of the combination of Diameter, Spacing and No. of Fibers on the illumination were also studied. The statistical analysis clearly shows that each parameter has an individual and combined influence on illumination.The weather conditions, cloud coverage and sun inclination affected the performance and the quantum of transmitted sunlight from month to month. The variants with larger optical fiber areas performed better independent of monthly variation, and luminance peaked around 12.30 p.m. as well.Typical graphs in When dealing with material dependent on weather, it is crucial to ascertain the behavior relative to the season. The study was focused on the coastal region of Karnataka, India, and the seasonal variation has been considered as per the Indian Metrological Department stipulations. An analysis of the variation of mixes M11 and M73 represents the behavioral trend for all mixes, as these reflect the most significant and smallest transmittance among all variants, as represented in Seasonal variation data for various mixes show us that there is a definite visual correlation between the transmittance and percentage fibers as well as the time of the day. The general trend carries through these results as well. Transmittance is reduced in the monsoon and marginally more prominent in the summers.A linear regression model for the relationship between the area of fibers and transmittance is also represented in The irradiance of sunlight is a measure of the light energy of the sun and is an indirect indicator of the intensity of sunlight on the surface of the earth at a specific place. The irradiance data were considered as datum to determine if there was an effect of this on the transmittance of concrete. Irradiance data were obtained for Mangalore International Airport, which is the closest metrological station available to the test location. These details were compared with transmittance, and the results are given in There is a strong dependency on the irradiance of the sun in the transmittance of light as their behavior is similar based on the time of the day. This is indicative of an interdependency that was further verified with MANOVA. The correlation between the area of fibers available for transmission and transmittance is evident. As the area of fibers increases, the transmittance also increases. This relationship is independent of the type or nature of the source of illumination. This is further proven when the area and number of fibers are studied, where variants of 1 mm diameter show transmittance up to 85.14% higher than 0.5 mm for the same spacing, just as the variants with a larger number of fibers per bundle exhibited transmittance in the range of 52.33–101.48% for the same spacing.The angle of inclination of the sun has an insignificant impact as the scattered light aids in providing enough intensity of light in the directions within the acceptance cone of the fibers, as the acceptance cone of the fibers is as large as 61°.Transmittance is highest in the months of April and May, with peak illumination being 360 lux and 372 lux, respectively. The sparse clouds and bright sun cause increased light to be available for transmittance, hence increased transmission occurs.The loss of illumination during monsoon is high, and, for most variants, the illuminance is below 300 lux, which indicates the need for artificial illumination during these periods of low light. The transmission ranges for the month of July range between 57 lux and 176 lux, where all the variants have significantly low transmittance in comparison with the other months.Most mixes have luminance in the 200–300 lux range, making them suitable for most commercial, public and industrial applications for most months during the year.In the present study, considering all the testing parameters and variables, the sample consisting of seven bundled 1 mm fibers with 12 mm spacing is found to have the best performance in light transmission.This study attempts to better understand the transmittance behavior of light-transmitting concrete with embedded optic fibers in natural sunlight. Based on the experimental and statistical investigation conducted at Manipal Institute of Technology, Manipal, India, these conclusions are derived:A limitation of the study is that the tests use a lux meter; hence, other appropriate testing techniques should be used for larger panels. The study shows a promising prospects of a material that can be used for light transmittance. The bundled fibers have been proven to be relatively more manageable and effective in producing structural light-transmitting concrete. They can provide adequate fiber spacing for aggregates with a higher fiber area for transmittance. Further investigation into the durability and placement techniques is necessary before the material is suitable for integration into the present industrial scenario.


To study the evolution of stress on the ring and segment interfaces during the construction process of the concrete encapsulation of the main arch ring in a rigid-frame arch bridge, alongside its impact on the ultimate load-bearing capacity of the main arch ring, a 1:10 scale model experiment was conducted by taking the 600 m Tian’e Longtan Bridge as the prototype. The key cross-section concrete strain data were collected during the entire construction process of the main arch ring via fiber-optic strain sensors, which were used to investigate the stress evolution at ring and segment interfaces. ANSYS APDL was employed to simulate the ultimate bearing capacity under various loading conditions of two different finite element models, which were, respectively, formed segmentally and by single pouring. The results revealed that (1) after the closure of the concrete encapsulation of the main arch ring, the concrete stress in the cross-section exhibits significant stress disparities. At the same cross-section, the level of the web concrete stress can reach 76% of the floor concrete stress, while the roof concrete stress level is less than 20% of the floor concrete stress. (2) At the junction of two adjacent work planes, there are considerable differences in the stress levels of the concrete on both sides. After the closure of the main arch ring, the intersegment stress ratios of the floor, web, and roof concrete are 60~70%, 40~60%, and 0~5%, respectively. (3) Loading conditions remarkably affected the ultimate bearing capacity of the main arch ring. Under mid-span loading and 1/4 span symmetrical loading conditions, compared to single-pour concrete encapsulation, the ultimate bearing capacity of the main arch ring with concrete encapsulated by segmented and ring-divided pouring decreased by 19.16% and 5.23%, respectively, compared to single-pour concrete encapsulation. This suggests that the non-uniformity of stress distribution in the concrete sheath can lead to reductions in the ultimate bearing capacity of the arch ring. The rigid-frame arch bridge is an advanced structural design featuring a strong steel truss as its backbone, whose concrete is poured into internal tubes and then covered with externally cast concrete in ring-segmented patterns . Such a Comprehensive research on the stress evolution laws at the interfaces between the floor, web, and roof concrete of the main arch ring (hereafter referred to as inter-rings interface) and adjacent work plans interfaces (hereafter referred to as intersegments interface), as well as the influence of stress distribution on the ultimate load-bearing capacity, is scientifically and practically significant. It aids in clarifying the transmission mechanism of concrete at different ages and stress levels and optimizing the loading state of the main arch ring.Currently, scholarly studies on the stress evolution during the construction process of external concrete encapsulation of the main arch ring in a rigid-frame arch bridge and its influence on the structural ultimate load-bearing capacity can be categorized into three types.The first category focuses on the impact of the longitudinal segments’ quantity and segmentation location of the external concrete encapsulation on the structural stress ,9. TheseThe second research category optimized the concrete encapsulation construction scheme based on controlling the stress and the line shape of the main arch ring ,14,15. FThe third category of research investigates the influence of various factors on the stress-bearing performance of the main arch ring from the perspective of limit-bearing capacity ,20,21. FIn summary, the majority of studies focusing on the stress evolution of the main arch ring tend to spotlight the summary of patterns. Although some scholars have proposed stress optimization methods, most of them rely heavily on numerical simulations and accomplish their research through trial-and-error selection, lacking experimental support from measured data. Furthermore, the research regarding the impact of the stress state of the main arch ring after construction completion on bearing performance remains a gap in the literature.Focusing on the dual issues of the lack of experimental data support for the stress evolution rules during the construction process of the main arch ring and the absence of studies on the impact of structural stress states on the ultimate load-bearing capacity, a 1:10 scale model experiment of the main arch ring was conducted based on the world’s largest rigid-frame arch bridge—the Tian’e Longtan Bridge—with a main span of 600 m. This 1:10 scale model has surpassed similar scale tests conducted on bridges worldwide previously ,27. ANSYThe Tian’e Longtan Bridge, with a main span of 600 m and a height of 125 m (height-to-span ratio = 1/4.8), is located within Guangxi Province, China. The main arch is composed of three parts: a rigid steel skeleton, concrete-filled steel tube, and the external concrete forming a box-shaped cross-section; the size information of the external concrete at different sections is shown in It should be pointed out that the load effect will vary with the change in scale, and a reasonable scale can improve the accuracy of inferring the original bridge state from the model test results. In addition, a smaller scale can lead to a smaller structure size, increasing the difficulty of welding the steel skeleton and the risk of pipe blockage during the pouring process of concrete inside the pipe. Additionally, thinner concrete will reduce the thickness of the protective layer of the steel bar. On the contrary, a larger scale will increase the demand for experimental space in the experiment. Considering multiple factors such as the load effect, availability of materials, the feasibility of steel structure fabrication, experimental space, and structural safety during construction, a scale of 1:10 was chosen for this experiment.In accordance with the principle of stress equivalence ,30, a maNotably, due to spatial constraints in the laboratory, the model experiment focused on a single arch ring. This focus made the issue of lateral stability of the main arch ring more prominent. To enhance the safety of the structure during construction, a limiting bracket along the longitudinal direction of the bridge every 10 m was arranged, as shown in To ensure stress equivalence between the model and the original bridge, the construction process required nine times the self-weight of the completed structure to be applied as a permanent load at the corresponding load points. The model arch is set with a loading point every 2 m along the longitudinal direction of the bridge, and a total of 29 loading points are set for the entire bridge. To enhance the local stability near the loading points, transverse partitions with a thickness of 50 mm are also arranged every 2 m along the length of the bridge . During Considering the primary arch ring segmentation, the external concrete was cast in 18 stages. Considering the erection of the rigid steel skeleton, the pouring of inner tube concrete, and the application of the permanent load balance weight, the primary arch ring was divided into 40 construction phases, as illustrated in The strain testing of externally wrapped concrete includes inter-ring strain tests at the 17 evenly distributed cross-sectional locations and strain tests near the section locations of the working plane of the concrete.The inter-rings interface refers primarily to the junction of the floor, web, and roof concrete, forming the three rings of the concrete structure, as depicted in In The structural strain can be calculated using Equation (1) and based on sensor wavelength data:In the equation, To eliminate the influence of environmental temperature during the construction process on strain data, temperature sensors T1–T3 are embedded within the externally wrapped concrete, evenly distributed at three section heights, and the corresponding calculation method is shown in Equation (2):In the equation, for this experiment, The intersegments interface primarily refers to the interface between two adjacent concrete sections within the same ring. When constructing externally wrapped concrete, a multi-plane balanced pouring method was used, and there is a particular age difference between the concrete on both sides of the intersegments interface. This age difference reaches its maximum when the interface is located between two adjacent working planes. To some extent, this difference reflects the timing of the concrete’s participation in structural loading and the duration of stress accumulation; hence, the stress difference between two sections of concrete often correlates positively with the age difference. Based on these considerations, three intersegment interfaces were selected along the main arch ring in the longitudinal direction. Two test sections were set up on either side of each interface, as shown in i-j, Bi-j, and Ci-j  respectively represent the concrete in the jth part of the ith workplane of the floor, web, and roof concrete. The three intersegments interfaces were located, respectively, at the junctions between work planes 1 and 2, 2 and 3, and 3 and 4. A test section, numbered from 1 to 6, was set up for each interface, with the sensor layouts for each section shown in In In To quantitatively analyze the evolution of interfacial stress in the main arch ring during the construction process of the encapsulated concrete, Hooke’s Law was used to calculate the stress in the arch foot section, ¼ span section, and mid-span section. The stresses in the floor, web, and roof concrete at various construction stages were extracted from these sections. The derived stress profiles are illustrated in To understand the changes in the relative stress state of the tri-ring concrete during the construction process of the main arch ring, we have calculated the stress ratios of the tri-ring concrete in the arch foot section, ¼ span section, and arch crown section during the construction process, as shown in In However, when pouring the roof concrete, there was no similar phenomenon as in the web concrete. There were two main reasons for this. Firstly, the roof concrete had a smaller volume than the web concrete, which resulted in a smaller load component along the arch axis due to the self-weight of the former. Secondly, after the roof concrete of the arch foot cross-section hardened, it participated together with the main steel tube and the concrete within the tube in the local load-bearing of the structure. They jointly bore the axial component of the self-weight load from the newly poured roof concrete.During the pouring of the encapsulated concrete in the main arch ring, each ring was divided into multiple work surfaces in the longitudinal direction, and each work surface was completed in multiple stages of pouring. Nth and the (N + 1)th work planes of each ring is represented as The construction sequence of the encapsulated concrete is shown in The stress results for the intersegments interfaces during the construction process of the encapsulated concrete in the main arch ring have been collated, as illustrated in As seen from In the pursuit of a comprehensive study on the influence of uneven stress distribution in the external concrete ring and segmental joints, following the closure of the main arch of a rigid-frame arch bridge, a finite element model of the main arch ring has been constructed. This model utilizes the robust capabilities of the ANSYS APDL 18.0 , offerinOur approach, encompassing numerical simulation and advanced computational mechanics, aims to reveal potential vulnerabilities within the structural integrity of arch bridges. By focusing on the uneven distribution of stress after the arch ring closure, we can better comprehend its effects on the overall load-bearing performance of these structures. In turn, the acquired insights can significantly contribute to improving bridge design and safety strategies and provide a robust foundation for further academic studies in this field.In During calculations, displacement and rotation in all directions are restrained at every node on the surfaces where the arch feet are erected. Load conditions consist of the self-weight of the structure and the actual counterweights at the model bridge’s loading points. The construction process of the main arch ring is simulated using birth-and-death elements.To validate the correctness of the finite element model, we have compared the stress results measured and simulated in the rigid steel skeleton, the concrete inside the tubes, and the externally wrapped concrete at some key cross-sections during various construction stages. These comparisons are graphically presented in Our comparison across multiple stages ensures a rigorous validation of our finite element model, thus enhancing its credibility and potential application for future research. This method facilitates a better understanding of the stress distribution and performance of different bridge elements, making a significant contribution to the overall field of structural engineering.As illustrated in During the casting of externally wrapped concrete, the maximum relative error between the simulated and experimental results of the concrete inside the tubes is 4.09 MPa, which occurs during the casting of the third segment of the floor concrete stage. The maximum relative error between the simulated and experimental results of the floor concrete throughout the construction process is 1.44 MPa.Throughout the construction process of the main arch ring, the stress results of the concrete inside the tubes and the externally wrapped concrete are significantly smaller compared to the main steel tube. Hence, the absolute error better represents the consistency between the ANSYS results and the experimental outcomes.Overall, the error between the simulated and experimental results falls within an acceptable range. These comparative results substantiate the finite element model’s accuracy, thereby supporting the rationality of employing this finite element model for subsequent calculations.Experimental results demonstrate that when using a segmented ring-based construction method for externally concreted rigid-frame arch bridges, significant stress differentials exist between the tri-ring concrete segments and longitudinally adjacent concrete sections. In order to investigate the impact of this phenomenon on the structural performance of the main arch ring after its construction, we apply the ‘birth-and-death’ element method based on the validated finite element model in In Model 2, the external concrete is activated simultaneously, meaning that all ringed and segmented concrete sections engage in structural stress simultaneously. After the completion of the sixth construction phase, the load-bearing distribution between and within the external concrete rings becomes more uniform, avoiding noticeable stress discontinuities. To quantitatively analyze the effect of uneven stress distribution between and within the rings of external concrete on the structure’s load-bearing performance, we referenced other scholars’ research methods in the arch bridge’s ultimate load-bearing capacity ,40,41,42The rigid steel frame of the main arch ring is made of Q420 steel. An ideal elastic–plastic model is used and simulated using the bilinear kinematic hardening model (BKIN) in the finite element model. As shown in E represents the elastic modulus of Q420 steel, with E = 2.06 × 105 MPa; In the equation, For the concrete material, the reference is “Code for Design of Concrete Structures” (GB50010-2010), . It is aIn the equation, In these Equations, It is worth mentioning that for the 1/4 span single-point loading condition, the ultimate load-bearing capacities of Model 1 and Model 2 are nearly equal. This is because, under this loading condition, the ultimate load-bearing capacity of the main arch ring is controlled by the yield strength of the material near the loading point. During loading, vertical deflection occurs at the loading point. As shown in (1)The construction order of the three rings of the main arch ring leads to differences in the timing of the floor, web, and roof concrete participating in the overall structural loading. After the closure of the main arch ring encased in concrete, the three rings of concrete exhibit noticeable stress differences. At the same cross-section, the stress level of the web concrete can reach 76% of the floor concrete stress, and the stress level of the roof concrete is less than 20% of the floor concrete stress.(2)The three rings of concrete exhibit a characteristic of converging stress levels as the construction stage progresses, mainly manifested as an increase in the inter-ring stress ratio of the encased concrete at the same cross-section as the construction stage progresses.(3)Due to the negative bending moment at the arch crown, casting concrete near the mid-span can significantly reduce the compressive stress level of the floor concrete. When casting the mid-span closure section web and roof concrete, the floor concrete compressive stress, respectively, decreases by 1.46 MPa and 0.89 MPa, with a decrease of 18.02% and 9.36%.(4)For the same ring of concrete, due to the casting order, there is a difference in the timing of the concrete participating in local structural loading. At the junction of the work planes, there is a certain difference in the stress levels of the concrete on both sides of the interface. After the main arch ring is closed, the intersegment stress ratios of the floor, web, and roof concrete are 60~70%, 40~60%, and within 5%.(5)ANSYS APDL was used to establish the finite element model of the main arch ring of the model bridge and the stress data of the top chord, inner concrete, and floor concrete on the rigid steel skeleton at the arch crown cross-section and the arch foot cross-section during the entire construction process were compared. The results show that each component’s measured stress and simulation results during the construction process generally match well, and the overall trend is basically consistent. Among them, the maximum relative errors of the simulation results and the measured results for the main steel tube, inner concrete, and floor concrete of the rigid steel skeleton throughout the construction process are 14.42 MPa, 4.09 MPa, and 1.44 MPa, respectively, verifying the correctness of the finite element model.(6)To study the effect of the uneven stress distribution of encased concrete on the ultimate load capacity of the main arch ring, ANSYS APDL was used to calculate the ultimate load capacity of the two finite element models of the main arch ring encased in concrete under normal construction (Model 1) and encased in concrete in one pour (Model 2) under four loading conditions: mid-span loading, 1/4 span single-point loading, 1/4 span symmetrical loading, and full-span uniform loading. The results show that the loading conditions significantly affect the ultimate load capacity after the closure of the main arch ring. Under mid-span loading and 1/4 span symmetrical loading conditions, compared to Model 2, the ultimate load capacity of Model 1 decreased by 19.16% and 5.23%, respectively, indicating that an uneven stress distribution of encased concrete will reduce the ultimate load capacity after the closure of the main arch ring.In order to investigate the stress evolution of inter-ring and intersegment interfaces during the separate ring and segment casting processes of concrete encasing the main arch ring of a rigid-frame arch bridge, and its impact on the ultimate load capacity, a 1:10 scaled model experiment was conducted on the main arch ring of the Tian’e Longtan Bridge with a main span of 600 m. Structural strain data at key cross-sections throughout the construction process were collected, and the stress evolution laws of inter-ring and intersegment interfaces were analyzed. The ANSYS simulation results and field data were compared, and the effect of uneven stress distribution of encased concrete on the ultimate load capacity under different loading conditions was calculated. The main conclusions are as follows:The next steps in the research will be to conduct related segment tests to clarify the stress evolution laws of the inter-ring and intersegment interfaces of ultra-large-span rigid-frame arch bridges under long-term service conditions, to define the load transfer paths between inter-ring and intersegment interfaces, and to conduct parametric analysis to study the impact of uneven stress on the ultimate bearing capacity of the main arch ring external concrete. Simultaneously, in conjunction with multi-objective optimization algorithms, we aim to minimize both the stress difference in the concrete of the floor, web, and roof concrete at the same section and the stress difference between adjacent segments of each ring of concrete. These are considered objective functions. With the maximum compressive stress of the concrete during the entire construction process as the constraint and the length of each working face of each ring of concrete as design variables, we plan to carry out research on the segmental optimization method for the external concrete of rigid-frame arch bridges. This is the task we are about to undertake.