EC+/dia+). To explore new therapeutic targets, Ishikawa is cultured with high glucose (IshikawaHG) mimicking hyperglycemia in patientEC+/dia+. Subsequently, it is discovered that IshikawaHG exhibits glucose metabolic reprogramming characterized by increased glycolysis and decreased oxidative phosphorylation. Further, pyruvate dehydrogenase kinase 1 (PDK1) is identified to promote glycolysis of IshikawaHG by proteomics. Most importantly, JX06, a novel PDK1 inhibitor combined metformin (Met) significantly inhibits IshikawaHG proliferation though IshikawaHG is resistant to Met. Furthermore, a reduction‐sensitive biodegradable polymer is adopted to encapsulate JX06 to form nanoparticles (JX06‐NPs) for drug delivery. It is found that in vitro JX06‐NPs have better inhibitory effect on the growth of IshikawaHG as well as patient‐derived EC cells (PDC) than JX06. Additionally, it is found that JX06‐NPs can accumulate to the tumor of EC‐bearing mouse with diabetes (miceEC+/dia+) after intravenous injection, and JX06‐NPs combined Met can significantly inhibit tumor growth of miceEC+/dia+. Taken together, the study demonstrates that the combination of JX06‐NPs and Met can target the cancer metabolism plasticity, which significantly inhibits the growth of EC, thereby provides a new adjuvant therapy for patientsEC+/dia+.Diabetes is closely related to the occurrence of endometrial cancer (EC) and its poor prognosis. However, there is no effective clinical treatment for EC patients with diabetes (patient EC+/dia+). This study provides a new adjuvant treatment for patientsEC+/dia+ in clinical practice, suggesting that JX06 to form nanoparticles (JX06‐NPs) combined with metformin is effective for achieving better antitumor effect by targeting cancer metabolism.Diabetes is closely related to the occurrence of endometrial cancer (EC) and its poor prognosis. However, there is no effective clinical treatment for EC patients with diabetes (patient Compared to nondiabetic patients, diabetic patients have twofold increased risk of developing EC. In addition, the mortality of EC patients with diabetes (patientsEC+/dia+) increases by 41%. Taking together, diabetes is important in the pathogenesis and prognosis of EC. However, in current clinical practice, there is no standard treatment for patientsEC+/dia+. Hyperglycemia is a major clinical feature of diabetes, which is also considered a key link between diabetes and cancer. Therefore, to control blood glucose level or to interfere with the molecular signaling pathway regarding glucose metabolism may be a new perspective for the clinical treatment of patientsEC+/dia+.Endometrial cancer (EC) is one of the most common gynecological malignancies. Its pathogenesis is closely related to estrogen imbalance and metabolic disorder. With the increasing incidence of metabolic diseases in the recent years, the incidence and mortality of patients with EC have accelerated globally.2, 3 In addition, a clinical study has shown that Met adjuvant therapy is effective in reversing endometrial atypical hyperplasia, reducing the expression of tumor markers for proliferation, and improving the overall survival of EC patients. However, other studies have demonstrated that the inhibitory effect of Met on the growth of EC cells is less prominent under high‐glucose conditions versus that in normal‐glucose conditions, which indicates that hyperglycemia may lead to Met resistance in EC cells. As elucidated by the Warburg effect, the glucose metabolism of tumor cells is glycolysis dominant (80%), with oxidative phosphorylation only taking up the rest 20%. In other words, tumor cells may manifest a “metabolic plasticity” or “metabolic reprogramming.” Further, the mechanism of resistance to Met under hyperglycemic conditions may be related to increased glycolysis. Therefore, a combination of glycolytic inhibitors and Met may have enhanced antitumor effect than with Met alone. The combination of hexokinase 2 (HK2) ablation and Met were proved to be synergistic in inhibiting hepatocellular carcinoma growth. However, the role of Met combined with glycolysis inhibitors in EC treatment with comorbidity of diabetes has not been reported. Thus, we hypothesize here that targeting the cancer metabolism plasticity via glycolysis inhibitors combined with Met may increase the sensitivity of EC cells to Met in a high glucose condition, which is of great clinical value for treatments of patientsEC+/dia+.Metformin (Met) is one of the most common diabetic drugs in the clinic. In recent years, studies have found that it could inhibit the growth of breast cancer, colon cancer, and EC cells. Its main mechanism as an antitumor drug is to inhibit oxidative phosphorylation by blocking the electron transfer of complex I in the mitochondrial respiratory chain and inhibiting the process of oxidative phosphorylation.12 In HG) concentration, with the same cell line cultured at a normal glucose (IshikawaNG) concentration as the control group. The main reason for choosing a long‐term high‐glucose cell culture was that most previous work had only studied the biological behaviors of EC cells under various glucose concentrations in a short timespan (0–72 h). However, diabetes is a chronic metabolic disease, manifesting as long‐term persistent hyperglycemia. Thus, a long‐term culture of cells in a hyperglycemic environment can more accurately simulate the actual in vivo interplay between glucose and EC. Subsequently, with IshikawaHG and IshikawaNG, we found that 1) compared to IshikawaNG, we observed on IshikawaHG a hyperglycemic environment exacerbated the transformation of glucose metabolism from oxidative phosphorylation to glycolysis. 2) The expression of pyruvate dehydrogenase kinase 1 (PDK1) for IshikawaHG, a rate‐limiting enzyme of glycolysis, increased significantly as compared to IshikawaNG. Downregulating the expression of PDK1 by short hairpin RNA (shRNA) could remarkably inhibit not only the proliferation, invasion, and glycolysis, but also the AKT/GSK3β/β‐catenin signaling pathway of IshikawaHG. 3) JX06, a small molecule inhibitor of PDK1, when combined with Met, accelerated the apoptosis of IshikawaHG. Although JX06 is potent in inhibiting PDK1, it has limited solubility in water, fast blood clearance, making it hard to be targeted delivered to the tumor sites and finally enter the cancer cells. Therefore, here we first adopted a reduction‐sensitive polymer (P1) with numerous disulfide bonds in its polymer chain, which could be triggered for degradation by glutathione (GSH)[rr]. Second, JX06 was encapsulated by P1 to form nanoparticles (JX06‐NPs). To fully simulate the pathophysiological characteristics of patientEC+/dia+, we subsequently induced diabetes in mice by intraperitoneal injection of streptozocin (STZ), followed by subcutaneous injection of EC cells. At last, we injected JX06‐NPs intravenously into the diabetic EC mice (miceEC+/dia+). JX06‐NPs entered cancer cells via the blood circulation, and then accumulated in the tumor sites, dissociated to release JX06 to inhibit PDK1. Met was concurrently administered orally, which played two roles. One was to reduce and control glucose level; the other was to inhibit mitochondrial complex I, suppressing the oxidative phosphorylation of tumor cells. By combining JX06‐NPs and Met, there was an increase of apoptosis of EC cells. Therefore, the combination of JX06‐NPs and Met has shown an enhanced antitumor effect under a high‐glucose condition, providing a new strategy for the treatment of patientsEC+/dia+.To prove this, we first established an EC cell line Ishikawa cultured at a long‐term high glucose (Ishikawa(0–72 h).21 How22.1P > 0.05). However, the proportion of patients with lymph vascular space invasion (LVSI) positive and deep myometrial infiltration (MI‐deep) were significantly higher in patients with high glucose level (HG‐patient) than that in patients with normal glucose level (NG‐patient)   medium, and IshikawaHG in a high glucose  medium for at least 8 weeks, and the cells were then used for subsequent experiments . To study the growth of EC cells, colony formation assay, Transwell invasion assay, and wound healing assay were performed. The results showed that the number of colony formation and invading IshikawaHG were 1.4 and 1.9 times that of IshikawaNG, respectively. Moreover, the scratch area was decreased for IshikawaHG versus IshikawaNG at 24 h  was significantly much higher than that in IshikawaNG (ECAR average is 26 mph min−1)   and extracellular acidification rate (ECAR), which reflected the oxidative phosphorylation and glycolysis energy metabolism, respectively, were assessed via the seahorse XF cell energy metabolism assay.27 The) Figure . Moreove) Figure . These r To further clarify whether mitochondria were affected as hyperglycemia shifts cellular metabolism to more of glycolysis, we used transmission electron microscopy (TEM) to histologically examine the Ishikawa cell lines and found that the mitochondria of IshikawaNG were morphologically regular; while mitochondria of IshikawaHG were significantly swollen, with dissolved, broken, or disappeared cristae , and enolase 2 (ENO2) from the glycolytic pathway were significantly upregulated  and 17 adjacent normal control endometrial tissue samples (patientNC) adjacent to EC specimens from EC tissue arrays were studied by immuno‐histochemistry. The samples were divided into three groups based on the level of PDK1 expression: negative/poor positive, moderately positive, and strongly positive. The results indicated that PDK1 was mainly expressed in the cytoplasm of cancer cells . Moreover, the proportion of tissue samples stained moderately and strongly positive for PDK1 were significantly higher in EC specimens than in normal tissues   and diabetic (patientsEC+/dia+) tissue samples. In this way, we could further show that the proportion of tissue samples stained strongly positive for PDK1 in the patientsEC+/dia+ group were significantly higher than that in the patientsEC+/dia− group   Figure . When th) Figure . Taken t) Figure . Moreove) Figure . BesidesHG and IshikawaNG, shRNA was transfected to downregulate PDK1 expression   . Thereafter, IshikawaHG transfected with sh‐NC or sh‐PDK1 was injected subcutaneously into the MiceDia+. In this way, diabetic EC mouse models of MiceDia+/sh‐NC and MiceDia+/sh‐PDK1 were obtained. Results indicated that reduced PDK1 expression results in smaller tumor sizes. We can clearly see that the tumor volume in the MiceDia+/sh‐PDK1 was on average 60% that in the MiceDia+/sh‐NC  values of JX06 on IshikawaHG at 24 and 48 h were ≈0.65× 10−6 and ≈0.35 × 10−6m, respectively  treatment group at 48 h  × 10−3m of Met could significantly inhibit the proliferation of both IshikawaHG and IshikawaNG. However, this inhibitory effect on IshikawaHG was not as prominent as that observed in IshikawaNG. The inhibition rate of 5 × 10−3m Met was 35% for IshikawaNG and 30% for IshikawaHG (P < 0.05)  and found that the intensity of red fluorescence in cells increased overtime, suggesting that the uptake of JX06‐NPs by IshikawaHG gradually increased . In order to further simulate the tumor microenvironment and the 3D spatial structure of tumor in vivo, an in vitro 3D cell culture spheroid was established, and the uptake of JX06‐NPs at different tumor sections in the 3D sphere was observed by the CLSM. It was found that from 5 to 20 µm of the sphere section, the intensity of red fluorescence increased significantly, while from 20 to 30 µm of the sphere section, the intensity of red fluorescence at the center of the sphere gradually decreased . JX06 encapsulation efficiency, loading capacity, and drug release were also evaluated. The results showed that JX06 encapsulation efficiency was 40% and the loading capacity was 4%. In addition, the release of JX06 from JX06‐NPs was measured, and the results indicated that there was a gradual increase in drug release at pH 7.4 and GSH =10 × 10−3m from 0 to 24 h. The drug releases were 24.83% (pH = 7.4) and 76.08% (GSH = 10 × 10−3m) at 24 h , and the drug sensitivity test schedule is shown in Figure −3m) was 65%, JX06 (0.5 × 10−6m) was 34%, and JX06‐NPs (0.5 × 10−6m) was 46%. This clearly showed that the inhibitory effect of JX06‐NPs was stronger than JX06. In addition, the antitumor effect of either JX06 or JX06‐NPs combined with Met was significantly stronger than the single use of JX06, JX06‐NPs, or Met. Moreover, JX06‐NPs combined with Met had an inhibitory rate at 86% as compared to JX06 combined with Met at 79%  was higher than Met alone (2.78%) and JX06‐NPs alone  and GLO1 after drug treatment. The results showed both the expressions of P‐p70s6K and GLO1 were decreased in IshikawaHG treated with 5 × 10−3 or 10 × 10−3m Met compared with PBS . The combinational use of Met and JX06‐NPs also showed to inhibit the expression of p70s6K and GLO1 compared with PBS, while there was no significant difference compared with single Met  have been used in drug sensitivity tests.47 To % Figure . To furt2.4EC+/dia+) to evaluate JX06‐NPs combined Met in vivo. First, to observe the accumulation of JX06‐NPs, JX06‐NPs were labeled with Cy7.5 and injected intravenously. The in vivo imaging showed that the fluorescence signal gradually increased at the tumor site overtime and reached to the maximum at 36 h  and liver (6.73 × 107)  Figure . The aboEC+/dia+ and nondiabetes EC (miceEC+/dia−) models were constructed. The treatment schedule for in vivo study is shown in Figure EC+/dia+ treated with saline was 1.3 times greater than that in miceEC+/dia−, confirming that high glucose promoted tumor growth. Moreover, Met treatment in miceEC+/dia+ and miceEC+/dia− both showed inhibitory effect on tumor weight. The tumor weight in miceEC+/dia− treated with saline was 1.6 times higher than that with Met. However, the tumor weight of miceEC+/dia+ treated with saline was 1.4 times greater than that treated with Met. As Met is a widely used diabetic drug, we hypothesized that the tumor inhibition of Met on miceEC+/dia+ may be closely related to its hypoglycemic effect. For the nanoparticles’ treatment group, we observed that the tumor weight of miceEC+/dia+ treated with JX06‐NPs was 0.872 g, significantly lower than that treated with JX06 (1.102 g) and saline (1.298 g), suggesting that JX06‐NPs could more significantly inhibit EC growth. Moreover, for the combination groups, JX06‐NPs combined with Met have the strongest inhibitory effect on miceEC+/dia+, and its antitumor effect is even stronger than that of JX06 combined with Met (average tumor weight: 0.54 vs 0.74 g)  staining results showed that the green fluorescence intensity of tumor cells in miceEC+/dia+ treated with JX06‐NPs, and Met was significantly increased, indicating more apoptosis of EC cells, which is consistent with H&E staining results  in tumor tissue from miceEC+/dia+ after treatment by immuno‐histochemistry. The results showed that compared with miceEC+/dia+ treated with saline, the expression of p‐PDHA1 was significantly decreased in miceEC+/dia+ treated with JX06, JX06‐NPs, JX06+Met, and JX06‐NPs+Met, since brown granules were decreased after treatments  Figure . We coul) Figure . Finallys Figure . To furt  inThe animal experiment was approved by the ethics committee of Peking University People's hospital (2020PHE093), and the ethical requirements of experimental animals and the animal welfare law were strictly adhered to during the experimental operations. The human study was approved by the ethics committee of the Peking University People’s Hospital.3HG and IshikawaNG, we found that long‐term high‐glucose culture exacerbated the transformation of metabolism from oxidative phosphorylation to glycolysis of EC. Subsequently, through mass spectrometry proteomic screening, we found that the expression of PDK1, a key enzyme of glycolysis in IshikawaHG was 3.33 times higher than that in IshikawaNG. We further used shRNA to knockdown PDK1 and found it significantly inhibited the proliferation, invasion, glycolysis, and AKT/GSK3β/β‐catenin signaling pathway of IshikawaHG, which confirmed the role of PDK1 in the malignant biological behavior of EC cells induced by high glucose. Next, we found that the inhibition rate of JX06, a PDK1 inhibitor combined with Met, on IshikawaHG was 2.5 times higher than that of Met alone. We subsequently delivered JX06 with JX06‐NPs with higher intracellular uptake and greater inhibitory effect. Moreover, the apoptosis rate on IshikawaHG induced by JX06‐NPs combined with Met was 5.2 times than that of Met alone. More importantly, through the PDC from patientsEC+/dia+, we found that the growth inhibition rate of JX‐06 NPs combined with Met was 1.32 times higher than that of Met alone, and its mechanism may be related to the inhibition of glycolysis pathway and oxidative phosphorylation dual metabolic pathway. Further, we established mouse models of miceEC+/dia+ and miceEC+/dia− and showed that the inhibition rate of Met on miceEC+/dia+ was less than that in miceEC+/dia−. On the miceEC+/dia+ model, JX06‐NPs and Met had combined inhibitory anticancer effects. Our study provides a paradigm of new adjuvant treatment for patientsEC+/dia+ in the near future clinical practice, suggesting that Met combined with JX06‐NPs is effective for achieving better antitumor effect.In summary, our study found that high glucose was closely related to LVSI positive and MI‐deep of EC. By establishing cell lines of IshikawaThe authors declare no conflict of interest.X.Y., Y.C., and J.Z. contributed equally to this work. JL.W., H.X., X.Y. contributed to the design of the project and mainly contributed to data analysis and drafting of the manuscript. LP.Z. synthesized the nanopaticles. X.L., LR.Z., T.H., X.W., and B.S. provided assistance in animal experiments. Y.D., Z.W., LJ.Z. provided clinical data. S.Y., Y.J., JQ.W., and Y.H. provided experimental guidance. X.D. helped to polish the language.Supporting InformationClick here for additional data file.


This work studies the possibility of incorporating different proportions of glass powder from the waste glass  produced during the glass recycling process into the manufacturing of mortar and concrete. For this purpose, the material is characterized by its chemical composition and pozzolanic activity, and the shape and size of its particles are studied. It is then incorporated as a substitute for cement into the manufacturing of mortar and concrete at 25% and 40% of cement weight, and its effect on setting times, consistency, and mechanical strength is analyzed. Its behavior as a slow pozzolan is verified, and the possibility of incorporating it into concrete is ratified by reducing its cement content and making it a more sustainable material. Each ton of cement emits around one ton of CO2 into the atmosphere from both the burning of fuel and the decarbonation of the raw materials of cement [2 emissions [Concrete is the most widespread construction material in the world. In 2017, around 45 million tons were used in Spain . The maiFor this reason, the use of solid waste material or industrial byproducts as a partial cement replacement  in concrete is a viable strategy for reducing the use of Portland cement and for, therefore, reducing the environmental and energy impacts of concrete production ,6.In the line of work of the study of incorporating waste into the concrete matrix, the feasibility of such incorporation of waste from the glass recycling industry has been investigated for several years as part of either mortar, concrete and cement ,9,10,11,The incorporation of this material into concrete will lead to improvements in two different areas. A waste product will be recovered directly from either inert solid waste management plants (those not deposited in glass recycling containers) or the rejection of material that cannot be used as cullet for producing recycled glass. This will reduce not only the volume of waste that has to be disposed at landfill sites, but also the amount of cement or fine aggregate in concrete, thus reducing the carbon footprint of the most widely used building material in the world. This would, therefore, contribute to the achievement of SDG12 “Responsible Consumption and Production” and SDG13 “Climate Action”.In 2019, 958.939 tons of glass were collected in Spain, of which 56,628 tons came from urban solid waste plants and the rest from specific glass containers, with a recycling rate of between 72% and 77% . Most ofAt the end of the 1990s, several research works began to study the possibility of incorporating glass powder (GP) into the concrete composition as a substitute for part of the fine aggregate ,19, as aRashad  publisheThe pozzolanic effect that would justify the partial cement substitution for GP is directly related to the size of the ground glass particles, which is bigger the finer the GP . A risin3S content in the clinker. Nonetheless, as it does not lead to new minerals forming in the clinker, it could be added in small fractions.The use of GP in cement raw mixes during clinker burning  does notAll studies clearly reveal that this topic is complex and further research is needed before introducing GP into the concrete matrix becomes common practice. However, the obtained results have shown that GP can contribute to achieve the desired mechanical strengths. In Spain, part of the glass recovered during the recycling process is reused for the purpose of producing new glass containers. In this process, part of that material cannot be reused due its inadequate size and has to be sent as waste material to solid inert waste landfills. One of the novelties of this research is that we used this waste material (fine cullet) to perform this research. Other researchers also used this same concept  in orderTherefore, the objectives of this work are to characterize GP obtained from the glass recycling waste produced in Spain, and to incorporate this GP into mortar and concrete in different proportions to study its influence on their properties in fresh and hardened states.The experimental study was divided into three sections. In the first section, the physico-chemical characteristics of GP were studied to measure its pozzolanic potential. Second, different cement mortars were manufactured in which one part of the cement was replaced with GP at 0%, 10%, 25% and 40%. Its consistency, setting time, and mechanical strength were then analyzed. Finally, different concrete mixes were manufactured, in which one part of the cement was replaced with GP at 0%, 25% and 40%. The consistency and evolution of the compressive strength of these concretes were studied.Glass powder was obtained from a product donated by the company FCC ámbito . This company has a plant that receives and processes glass, where the material obtained during selective collection arrives. From this material, a cullet is obtained and sent as raw material to the main glass manufacturers. It is reintroduced into the market which, thus, favors fulfilling circular economy principles. During the process of recovering the product obtained from glass recycling, a waste glass (fine cullet) is produced destined for landfills. This is the material that was subsequently ground to obtain the GP used in this work. Grinding was carried out in an industrial pendular mill, which has a set of pendulums with rollers at the ends that grind material at high pressure against a grinding ring. Pressure is created from the high-speed rotation of the star from which the pendulums hang.The cement used to prepare paste, mortar, and concrete was CEM I 42.5R cement, which was supplied by the CEMEX factory in Buñol .The sand used for mortars was a mixture of three fractions to obtain a similar size distribution to that of normalized sand. The sand was siliceous and came from SILICAM  and had a fineness modulus of 4.3. For the concrete mixes, three gravels of sizes 4/8, 8/16 and 16/20 were used as coarse aggregates, while a combination of two sand types was used as fine aggregates by combining a coarser sand 0/6 named “red sand” and a finer sand 0/2 called “white sand”. All these aggregates are silico-calcareous aggregates. For concrete mixes, Sika Viscocrete 5970 (polycarboxylate-based) was used as a superplasticizer . The amount of additive used was 0.5% by weight of binder.Several techniques were followed to characterize GP. The chemical composition of GP was measured with a Philips Magix Pro spectrometer  via the X-ray flourescence (XRF) technique. The equipment used to measure granulometric distribution was a Mastersizer 2000 . The technique that employed the equipment was laser diffraction. GP was dispersed in water. Bruker AXS D8 Advance equipment  was employed to measure the X-ray diffraction (XRD) analyses. The range of measures went from 10 to 70 2θ degrees, with Cu Kα radiation at 20 mA and 40 kV, and a 2 s accumulation time in a 0.02 angle step. Finally, the GP morphology was observed under a field emission electronic microscope. The employed equipment was an FESEM ULTRA 55 scanning electron microscope.  Samples were carbon-coated in order to observe them and images were taken at 2 kV.For the thermogravimetric (TG) analyses, plain cement paste and cement/GP pastes were manufactured. The pastes were made under the same conditions as the mortars but without aggregate. The mixture was put inside a cylindrical plastic container with a hermetic closing until the testing age. For a given curing age, a paste sample was taken and milled in an agate mortar with acetone to stop the hydrating process. This ground sample was filtered and dried off for 30 min at 60 °C. Finally, it was sieved through a 125 μm sieve and was ready for further TG analyses. For field emission scanning microscopy (FESEM) purposes, a piece of paste was placed in acetone for 1 h and dried off for 30 min at 60 °C. The TG analyses were carried out using a TGA 850 Mettler-Toledo module  to take measurements up to 1100 °C. The utilized equipment had a horizontal electrobalance, a furnace, and temperature sensors connected to a computer in which data were recorded and processed by specific equipment software. The ultramicrobalance resolution was 0.1 µg. For the analysis of the cement pastes with GP, 100 μL aluminum crucibles were used with sealed covers, which had microholes to provide a self-generated water vapor atmosphere, which, in turn, allowed better resolution of the TG curves. For pastes, the selected temperature range was 35–600 °C with a 10 °C/min heating rate and a nitrogen atmosphere at a 75 mL/min flow rate.The Frattini test is a test for determining pozzolanic activity. This test is described in Standard UNE-EN 196-5 : “MethodThe cement mortar was prepared according to the specifications of the Spanish standard UNE-EN 196-1 , where tThe consistency of mortar was determined using the flow table method UNE-EN 1015-3 . The floFor the setting time test according to UNE EN 196-3 , the staThe mechanical strengths of the 40 mm × 40 mm × 160 mm prismatic mortar specimens were determined according to UNE EN 196-1 . SamplesConcrete was made in an electric mixer (40 L capacity) in which batches of 20 L and 25 L were prepared. In order to check the effect on the fresh concrete structure of GP incorporation into the concrete matrix, slump and compressive strength tests were carried out on concrete mixes. The slump test was used to measure the consistency or workability of the fresh concrete following UNE-EN 12350-7  and for The chemical composition of the GP is provided in 2 (Q) (PDFcard 331161), and traces of calcite, CaCO3 (C) (PDFcard 050586) and wollastonite, CaSiO3 (W) (PDFcard 100489).The obtained X-ray diffractograms are represented in Previous research has indicated that GP size is critical for the material to show pozzolanic activity . The sizTo date, it has not been possible to obtain smaller GP sizes following an industrial grinding procedure. In future studies, finer GPs should be studied to verify the influence of their particle size distribution on their pozzolanic character and to estimate if it is necessary to obtain alternative grinding methods to obtain a finer product.The morphology of GP particles was evaluated by FESEM. As Two methods were chosen to analyze the material’s pozzolanic reactivity, which are methods with different methodologies that do not always lead to the same result. Fratini is the normative method  and TG, In order to test the pozzolanity  of GP, sOnce the concentrations of hydroxyl and calcium ions, expressed as calcium oxide, in the solution had been obtained, they were featured in The reactivity of GP on the fixation of portlandite generated during the hydration of the Portland cement was studied by means of TG analysis of the corresponding cement/GP pastes at curing ages of 7, 28 and 210 days. The chosen percentage of cement replacement with GP was 25%. C is the quantity of portlandite (lime) present in the control paste, CHP is the quantity of portlandite present in the paste with GP and C% is the percentage of cement present in the paste (0.75 in this case).In the cement pastes with replacement materials, fixed lime was a function of the calcium hydroxide contained in the control paste (only cement as a binder). The following expression (1) was used to calculate the fixed lime percentage :(1)% HydThe fixation analyses with the 25% cement replacement with GP showed negative lime fixations for both the 7 and 28 curing day periods. At 210 curing days, the fixed lime value was 3.4. In this case, at 7 curing days, the paste with the waste glass had a negative value of −0.61%, which increased to −16.21% at 28 curing days. Negative lime fixation percentages are typical of long-term reactive pozzolans, such as fly ash . The negPayá et al.  describeThe micrographs obtained via FESEM of pastes at 28 curing days are presented in When replacing cement from the mortars with GP, consistency only slightly reduced for the 40% contents. Those mixes with the 25% cement replacement obtained the same consistency results as the reference mortar mix. To carry out the setting time test, a standard consistency paste was made according to UNE-EN 196-3 , which cThe obtained results show a delay in the final setting time in the pastes with GP, but with similar times at the start of the setting time.The cement mortar specimens made by replacing a percentage of cement with GP  were tesThree batches for each type of mortar  were produced. From each batch, 3 specimens were tested to flexural strength at the ages of 7, 28 and 90 days , and 6 specimens were tested to compression strength at the same ages .The obtained flexural strength values , left haAs previous research has shown , replaciPu  proposed3, (2) GP25 concrete 2220 kg/m3, and (3) GP40 concrete 2183 kg/m3.Concrete was produced in two batches of 25 L per type of concrete . From each batch, two specimens were produced to test compression strength at the ages of 7, 28, and 60 days (data could not be obtained at 60 days due to COVID-19 restrictions). The density measured for these mixes was: (1) control concrete 2375 kg/mThe concrete specimens made by replacing a percentage of cement with GP  were tesThe results show the pozzolanic behavior of the concretes into which GP was incorporated. If we look at compressive strength evolution, we find that the control mortar showed a 7.93% increase in resistance at 28 days, and one of 16.46% at 167 days. These values were higher for the 25% substitution of cement for GP with 25.96% and 44.67% at 28 and 167 days, respectively. These values were even higher for the concrete with the 40% substitution of cement for GP in which increased resistance would be 34.65% and 49.59% at 28 and 167 days, respectively.This indicates that despite the slight decreased strength in those concretes in which part of cement was substituted for GP, pozzolanic behavior was observed along with greater strength gain over time. These results are similar to those obtained by Tamanna and Tuladhar  with difThis research studied the use of glass powder from the waste generated in the glass recycling process (fine cullet) as a partial cement replacement in mortars and concrete. The experimental results obtained in this work allowed us to conclude that:GP acts as very slow pozzolan. Mortars and concretes with GP cement substitution always showed a low compressive strength compared to the controls. The decrease in strength was greater the higher the percentage of GP substitution. However, when analyzing the activity index, it was observed that this decrease in strength decreased over time, which confirms GP’s performance as a slow pozzolan. This behavior was also verified by the results obtained in the pozzolanic reactivity test (Fratini) and in the thermogravimetric analysis. Replacement percentages of 40% GP may be excessive, but replacements of up to 25% can guarantee enough strength for elements that are not extremely demanding. The incorporation of GP into mixtures did not strongly influence concrete setting time, but slightly delayed the final setting time. The density of mortars and concretes with GP decreased, and this decrease was greater the higher the percentage of substituted cement due to the low specific gravity of glass powder.Finally, GP lowered the Abrams cone value due to its larger specific surface area and the more angular texture of GP particles compared to the cement that was replaced.All the findings of this experimental study indicate that using GP from glass recycling process waste in mortar and concrete production is possible. This is a very important fact because it proposes replacing a portion of cement with a material that is normally taken to landfills. The outcome of this research aims to contribute toward sustainable development by reducing the consumption of cement as well as a reducing the amount of glass waste going to landfills. Future research will study lower replacement percentages to find the optimum ones in terms of ecological benefits and minimum performance loss.


The most common structural defect of a tunnel in the operation period is the cracking of concrete lining. The insufficient thickness of tunnel lining is one of the main reasons for its cracking. This study studied the cracking behavior of standard concrete specimens and the failure behavior of tunnel structures caused by insufficient lining thickness using Cohesive Zone Model (CZM). Firstly, zero-thickness cohesive elements were globally inserted between solid elements of the standard concrete specimen model, and the crack development process of different concrete grades was compared. On this basis, a three-dimensional numerical model of the tunnel in the operation period was established. The mechanism and characteristics of crack propagation under different lining thicknesses were discussed. In addition, the statistics of cracks were made to discuss the development rules of lining cracks quantitatively. The results show that the CZM can reasonably simulate the fracture behavior of concrete. With the increase in concrete strength grade, the number of cohesive damaged elements and crack area increases. The insufficient lining thickness changes the lining stress distribution characteristics, reduces the lining structure’s overall safety, and leads to the cracking of the diseased area more easily. When surrounding rock does not contact the insufficient lining thickness, its influence on the structure is more evident than when surrounding rock fills the entire lining thickness. The number of cohesive damaged elements and the size of the crack area increases significantly. The tunnel was affected by different degrees of damage during operation. The most common structural damage was lining crack damage ,2,3. AccThe main reason for the disease of insufficient lining thickness was improper site construction, resulting in the insufficient excavation of surrounding rock . Given tLackner and Amorim et al. established a calculation model to simulate the cracking of shotcrete and secondary lining concrete, respectively . Zhang CCZM is widely used to study the cracking of composites. Ahmad Amiri-Rad studied high cycle fatigue delamination in composite materials. CZM was used to simulate fatigue-driven delamination growth . Ofir ShThe mechanical properties of tunnel lining structures were widely studied. In this paper, the feasibility of CZM in ABAQUS, in order to simulate the fracture behavior of concrete, was verified by the simulation of the cracking behavior of standard concrete specimens. On this basis, the cracking mechanism of the concrete lining structure of highway tunnels with insufficient lining thickness was studied. The evolution process of cracks in tunnel lining structure was deeply analyzed. The influence mechanism of insufficient lining thickness on crack evolution of tunnel lining structure was obtained.In order to verify the feasibility of CZM to simulate the cracking behavior of concrete structures, a three-dimensional model with the same size as Testing Methods of Cement and Concrete for Highway Engineering was established in ABAQUS. The model size is 150 mm × 150 mm × 150 mm. A loading plate without thickness was set, endowed with an elastic modulus much higher than the specimens to ensure that the load could be uniformly applied on top of the specimen. The vertical displacement at the bottom of the model was fixed. The model and boundary conditions are shown in For simulating the dynamic development of concrete cracks without preset paths, zero-thickness cohesion elements were embedded between solid elements to form potential crack surfaces ,26,27. IThis section took C40 concrete as an example for studying the cracking characteristics and crack development rules. In order to better observe the cracking of the model, we selected two perspectives, as shown in In ABAQUS, the cracking mechanism can be identified by the damaged typed of cohesive elements  . Accordi2, 153,708 mm2, 112,587 mm2 and 94,828 mm2, respectively. As can be seen from the crack distribution in This section analyzed the distribution form, crack area, and crack damage form of cracks under the same loading conditions by comparing the cracking of different strength grades of concrete: C15, C20, C30, and C40. According to The second section of this paper verified that CZM could be used to study the fracture of the concrete lining structure of highway tunnels. Therefore, this section uses CZM to study the cracking of lining structures under insufficient thickness of typical defects. The numerical model is shown in In this section, four values of 3 MPa, 5 MPa, 8 MPa, and 10 MPa are selected to discuss the characteristics of fracture and crack propagation under contact and non-contact conditions. As shown in This section shows the damage types of cohesive elements in the propagation phase in In order to clarify the characteristics of fracture evolution, the number of damaged cohesive elements, crack area, crack volume, and damaged form of cohesive elements were explored. With the increase in applied load, the crack area and volume further increase. In addition, it was also noted that the crack volume in non-contact conditions was much larger than that in contact conditions. From In this paper, the CZM is used to study the cracking mechanism of highway tunnel lining structure under insufficient lining thickness. The main conclusions are as follows:The feasibility of CZM in ABAQUS to simulate the fracture behavior of concrete was verified by the simulation of the cracking behavior of standard concrete specimens. Concrete is mainly subjected to shear failure in the compression process, which can be divided into three stages: stage I accumulates energy, stage II increases the number of cracks rapidly, and stage III increases the number of cracks slowly; small cracks gradually merge into large cracks. When the concrete strength grade is lower, the collapse of the edges and corners of concrete specimens are more pronounced. As the increase in concrete intensity grade, concrete crack area, and maximum crack width increase, long crack quantity increases and concrete surface crack quantity density decreases.When the lining thickness was insufficient and did not contact the surrounding rock, cracks began to appear when the load increased to about 3 MP under gradual loading. With the increase in load, the area of circumferential cracks increased gradually, and the radial cracks appeared and developed. The damaged form of cracks changes from tensile damage to shear damage. The number of cohesive elements damaged, in general, increases rapidly, and the collapse phenomenon occurs on the inner surface of the lining with insufficient thickness. When the wall rock is full of the entire lining, thickness is insufficient. With the increase in load, there is almost no external surface of cracks. A large number of disordered short circumferential cracks were distributed on the inner surface. The damaged form is mainly tensile damage. In general, insufficient lining thickness significantly influences the cracking of concrete lining structures, and the impact of non-contact conditions is substantially more effective than that of contact conditions.


Different aggregate gradations of asphalt concrete possess dissimilar skeleton structures, leading to diverse macroscopic and mechanical characteristics. Acoustic emission (AE) technology can realize real-time monitoring of the whole damage evolution process of materials. The objective of the present investigation was to demonstrate the fracture characteristics of asphalt concrete with three types of aggregate gradations, including dense-graded asphalt concrete (AC), stone mastic asphalt (SMA), and open-graded friction course (OGFC) under indirect tensile load on account of the acoustic emission (AE) technique. The Marshall compaction method was used to prepare specimens, and the indirect tensile test (IDT) and AE monitoring were conducted simultaneously at different temperatures. The corresponding AE parameters containing energy, cumulative energy, count, and cumulative count were adopted to characterize the fracture process of asphalt concrete with different aggregate gradations. The impact of temperature on the damage characteristics of asphalt concrete was also assessed. Test results indicated that the AE parameters could effectively classify the damage stages of asphalt concrete, and specimens with different aggregate gradations exhibited different AE characteristics during failure processes. The combination of AE parameters and cumulative AE parameters can accurately characterize the damage characteristics of asphalt concrete. SMA specimens possessed the best overall performance among these three types of asphalt concrete in terms of the variations in energy and cumulative energy at different temperatures. The findings obtained in this study can provide a practical AE-based evaluation approach for demonstrating the fracture mechanism of asphalt concrete with different aggregate gradations. Asphalt concrete is a heterogeneous material consisting of multiple components, which can be divided into dense-graded asphalt concrete (AC), stone mastic asphalt (SMA), and open-graded friction course (OGFC), according to the varied compositions of gradation . These tThe mechanical performance of asphalt concrete is usually characterized by a resilient modulus, flow number, and indirect tensile strength ,4. ConveHowever, limited work has been undertaken to validate the applicability of AE technology to characterize the damage mechanisms of asphalt concrete . Arnold Previous research has only focused on one type of aggregate gradation to evaluate the AE characteristics of asphalt concrete during the failure process, where the effects of aggregate gradations on fracture characteristics of asphalt concrete with AE parameters have been neglected. The aggregate gradation has a significant impact on the mechanical properties of asphalt concrete ,27. MoreIn this study, specimens with three aggregate gradations containing AC, SMA, and OGFC were prepared in line with the Marshall compaction method. Indirect tensile tests (IDT) and AE tests were conducted simultaneously to explore the impact of aggregate gradations on the AE parameters, including energy, cumulative energy, count, and cumulative count during the damage process. Moreover, the temperature effect on asphalt concrete with different aggregate gradations was also demonstrated based on AE parameters.The aggregates and filler were both derived from limestone, and the specific indicators are listed in Asphalt concrete with three types of aggregate gradations containing AC, SMA, and OGFC was prepared, and the maximum nominal size of each type of aggregate gradation was 13 mm. IDT was conducted with a universal testing machine shown in  producedFirst, the SR150M ceramic AE sensor with frequency bands ranging from 60 kHz to 400 kHz and a resonant frequency of 150 kHz was immobilized on the side of the specimen by adhesive tape and coupled with grease. The pencil lead break was then carried out to ensure a favorable coupling condition between the sensor and specimen, after which the load was applied to the specimen and the AE parameters containing the energy and count during the fracture process were recorded by the AE instrument. The whole process is schematically presented in The fracture behavior of the three types of asphalt concrete was characterized by AE parameters containing energy, count, amplitude, rise time, and duration. It has been reported that all these parameters exhibited similar variations during the damage process of asphalt concrete . In thistF is the real-time load and mF is the maximum load.Three types of asphalt concrete with different gradations, including AC, SMA, and OGFC, were prepared. The nominal maximum size of an aggregate with different gradations was 13 mm, and the corresponding temperature of the IDT was set to 25 °C. AE parameters, including energy and count, were used to characterize the fracture behavior of specimens with different aggregate gradations. The fracture process of asphalt concrete can be split into several stages in terms of the variations in the AE parameters. The loads were uniformly transformed into load levels that intuitively characterized the correlation between mechanical and AE parameters. The value of load level can be calculated by Equation (1).The AE energy distribution of AC specimens is presented in As seen in From a structural point of view, the traditional continuous dense-grade asphalt mixture is the suspend-dense structure, whose strength mainly derives from the cohesive force of the asphalt binder to aggregates. The asphalt concrete was subjected to a tensile force under indirect tensile load. In the initial stage, the asphalt binder and aggregate exhibited favorable cohesion and strong integrity, the cracking activities were not vigorous, and the phenomenon that the AE energy and count was at a relatively low level during the first three stages also confirmed this statement. When the load exceeded the tensile strength of specimens, final brittle fracture emerged, and the drastic increase in the AE energy and count in the final stage also authenticated this analysis.As shown in The cumulative count distribution of SMA specimens is observed in SMA specimens belong to the discontinuous gradation in grading types, and the gaps of the skeleton composed of coarse aggregates are filled with fine aggregates and asphalt binders in reasonable proportions, leading to the formation of the stable structure with an excellent packing effect. The internal friction and cohesion emerged to resist the displacement of asphalt concrete when the load was applied. The significant difference in AE characteristics between SMA and AC specimens lied in that the energy and count of SMA specimens were more uniform than those of AC specimens, and there was no drastic increase in AE parameters compared with AC specimens throughout the IDT process, which is attributed to the stable skeleton-dense structure.As seen in As shown in OGFC specimens belong to the continuous open gradation in gradation type, and it is a skeleton-void structure with large air voids, where the structure is composed of a large number of course aggregates and a small number of fine aggregates. The voids between the skeleton cannot be adequately filled by fine aggregates, which leads to the inability to form a strong interlocking effect between the particles. The strength of OGFC specimens mainly relies on the cohesive force between the binder and aggregates. The air voids of OGFC specimens are relatively large, and the contact state between particles is stone-to-stone, making the OGFC specimens prone to stress concentration in the IDT process. The cracks occurred and released a considerable quantity of AE energy when the stress concentration accumulated to a critical extent. Thus, the energy and count mutation points of OGFC specimens were intermittently distributed throughout the IDT process.The combined analysis of AE parameters and cumulative AE parameters enables the accurate classification of the fracture process in asphalt concrete. These three types of asphalt concrete exhibited different fracture characteristics during the failure process owing to their dissimilar skeletal structures. The internal damage of AC specimens developed slowly in the early loading stages but accumulated sharply in the final stage until they were completely destroyed. The SMA specimens displayed a steady development of internal damage under loading until the final fracture. The OGFC specimens were accompanied by localized damage throughout the failure process due to stress concentration.t is the loading time and ot is the overall loading time.Energy and cumulative energy were employed to assess the influence of testing temperature on the damage characteristics of specimens. The IDT and AE tests were conducted simultaneously at the temperatures of −10 °C and 25 °C, respectively. Time data were converted into time levels to characterize the variation in AE parameters visually with temperature. The value of the time level can be calculated by Equation (2).As seen in As mentioned above, the AC specimens possess the suspend-dense structure, whose strength mainly derives from the cohesive force of asphalt binder to aggregates. The change in temperature leads to the variety of cohesion between binders and aggregates, which affects the mechanical performance of specimens. Thus, the change in temperature significantly affects the AE parameters of asphalt concrete during its failure process.The cumulative energy distribution is presented in The strength of SMA specimens mainly derives from internal friction and cohesion. The change in temperature affects the cohesion of SMA specimens to a certain extent, but SMA specimens rely more on the internal friction of the skeleton-embedded structure to bear the load. Thus, the variation in energy and cumulative energy versus time is less affected by temperature.The energy distribution of OGFC specimens is illustrated in The strength of OGFC specimens mainly relies on the cohesive force between binders and aggregates. The change in temperature leads to the change in cohesion between the binder and aggregates, causing the fluctuation in mechanical properties. Thus, the temperature shows a significant impact on the AE parameters of OGFC specimens during the IDT process.The AE technique provides a new method to estimate the temperature stability of asphalt concrete. Combining the variations in AE parameters of these three types of asphalt concrete at different temperatures, it can be seen that the AE activities at −10 °C were more intense and the internal damage of asphalt concrete developed later compared to 25 °C. In addition, the SMA specimens exhibited the best temperature stability based on the AE parameter analysis. Compared with the traditional mechanical parameters, the AE parameters were more sensitive to the internal damage of asphalt concrete, which could help us understand the fracture mechanisms of asphalt concrete comprehensively.Asphalt concrete with different aggregate gradations exhibited different fracture characteristics based on AE monitoring, and the comprehensive analysis of AE parameters and cumulative AE parameters can realize accurate identification of the damage process of asphalt concrete.The damage fracture of AC, SMA, and OGFC specimens can be divided into four, three, and four stages due to AE parameters, respectively. As for AC specimens, the fracture characteristics were manifested by the sudden fracture due to insufficient cohesion under critical load. The fracture process of SMA specimens was characterized by the stable propagation of cracks owing to the stable skeleton-dense structure. Due to the high voids content, the fracture characteristics of OGFC specimens were represented as the local failure caused by the stress concentration related to the skeleton-void structure throughout the IDT process.The energy and cumulative energy of AC, SMA, and OGFC specimens varied with temperature, and the SMA specimens displayed the best overall performance among these three kinds of asphalt concrete in terms of the distribution of AE parameters at different temperatures.In this study, the fracture characteristics of asphalt concrete with three aggregate gradations, including AC, SMA, and OGFC, under IDT using the AE technique were demonstrated, and the temperature effects of asphalt concrete characterized by AE parameters were also discussed. The most relevant conclusions are:


Ammonia-soda residue (ASR) is the main solid waste generated from soda manufacturing and is hard to reuse due to its complex chemical composition. This study investigated the influence of ASR content on the strength and chloride-resistance capacity of concrete based on basic oxygen furnace slag and ground blast furnace slag. The hydration and chloride resistance mechanisms were analysed by comparing the hydrate products and pore structural changes. The results showed that adding ASR had the greatest impact on early strength. ASR-introduced chloride ions may participate in the hydration process to generate Friedel’s salt and decrease ettringite. The optimum pore distribution appeared when the ASR-to-desulphurisation gypsum ratio was 2:3 because of the introduction of nucleation sites and the decrease of C–S–H gels. The two chloride resistance-capacity measurements were affected differently by the ASR content. The apparent chloride diffusion coefficient was mainly affected by the percentage of pores that were larger than 10 nm. However, electric flux increased when ASR increased due to the influence of introduced chloride. The crystallisation pressure of Friedel’s salt decreases the strength of concrete with ASR content after high-concentration artificial-seawater immersion. The significant chloride-resistance property provided an alternative use for the concrete containing ASR. Becaud quartz . An inap−, ASR was mostly used to produce cementitious materials and concrete. The addition of ASR could prevent concrete shrinkage due to the generation of ettringite [− would be captured by cement [Although ASR might be used to produce engineering soil  and porotringite . The Cl−y cement , GBFS [5y cement , or fly y cement  due to tBasic oxygen furnace slag (BOFS) and ground blast furnace slag (GBFS) were widely used to produce cementitious materials, BOFS–GBFS-based binder and BOFS–GBFS-based concrete ,13,14,15− at the beginning of hydration. Although BOFS–GBFS-based binders can bind some chloride in Friedel’s salt and C–S–H gels, the captured Cl− may reduce the further chloride-binding capacity of paste in a chloride environment. On the other hand, the calcite introduced by ASR would influence the porosity of the binders [However, the chloride-resistance ability of concrete, which affected its use in corrosive environments, was not well-discussed in previous studies. The addition of GBFS could improve the chloride binding , perfect binders . Therefo4 and CaCl2 in ASR, ASR’s addition may also act as activators [Considering the CaSOtivators ,20. Ther2S), dicalcium ferrite (C2F), lime, periclase, and RO phase, while the GBFS mainly presented as amorphous phases. ASR mainly consisted of calcite, halite, gypsum, and hemihydrate gypsum. All of the raw materials were oven-dried before further treatments. The GBFS, BOFS, and DG were ground into powders with the specific surface areas in The cementitious materials in this work consisted of GBFS , BOFS , DG , and ASR . The chemical composition and specific surface area are shown in The iron tailings were provided by Beijing Miyun Weike Mining Co., Ltd.  as coarse (5–25 mm) and fine (0.08–5 mm) aggregates. A polycarboxylate superplasticiser was also applied to adjust the concrete mix fluidity.3. Based on previous studies [The mix proportion of the concrete is shown in  studies , the BOFThe concrete samples were produced on the basis of the proportion in The compressive strength (average of three samples) was measured using cubic concrete after 3, 28, 60 and 180 days curing according to the Chinese standard GB/T 50081–2002. A high concentration of artificial seawater was prepared  to studyConductivity and chloride penetration in a high-concentration solution was used to measure chloride resistance. The conductivity was determined using an electric flux according to the Chinese standard GB/T 50082-2009 for the long-term performance and durability of ordinary concrete . The conTo investigate the penetration process of chloride ions, two cylindrical samples of each group with epoxy resin-coated sides and bottoms were immersed in high-concentration artificial seawater  for 28 d−1. The paste piece with a diameter > 5 mm was used to conduct the mercury intrusion porosimetry with an Autopore IV 9510 mercury porosimeter. The instrument was provided by Micromeritics Instrument Co. . The microstructure and morphology of the hydrate products were studied using field-emission scanning electron microscopy. The lamellar paste was coated with gold to enhance conductivity. Zeiss Co  provided the SUPRA-55 field-emission scanning electron microscope used in this analysis. Dispersive-energy X-ray (EDX) spectroscopy was used to determine the element composition.The phase change of the paste powder was measured using an X-ray diffraction analysis with a scan angle of 5° to 90° and a step of 0.02°. Rigaku Co.  provided the XRD instrument with a copper target and an Ultima IV diffractometer. The bond transformation of the paste was evaluated using Fourier transform infrared spectroscopy. Shimadzu Co.  provided the spectrometer with a model FTIR-8400s. The wavenumber varied from 400 to 4000 cmThe compressive strength of the concrete is shown in The electric flux was chosen to represent the conductivity change based on the conductivity measurement. A better conductivity indicated that the concrete transported more chloride ions under the same voltage, which indicated poor chloride resistance. The results are shown in Based on Fick’s second law, the chloride ion concentration data in −12 m2/s when the ASR-to-DG ratio was 2:3 and the maximum value of 8.35 × 10−12 m2/s when the alumina-soda residue-to-gypsum ratio is 3:2.The C represents the chloride concentration at depth x and time t. Cs is the surface chloride ion concentration, and Ci is the initial chloride-ion concentration of the samples. Da is the apparent chloride diffusion coefficient, and erf is the error function. The fitting curve is shown in 2S, Friedel’s salt, and quartz. Despite the gypsum, calcite, and C2S coming from raw materials , ettectively . With th−1 and 1625.70–1639.20 cm−1, which belong to the O–H bond deformation and stretching vibrations [−1 was attributed to the internal stretching vibrations of the Si–O–Si bond in C–S–H gels [−1) appeared at the A3 group. −1. When the two spectra were combined, there were two bands at 1116.58 and 601.68 cm−1, which were correlated with the asymmetry and symmetry vibrations of SO42− from gypsum and ettringite respectively [−1 was attributed to the Si–O–Al bond in GBFS [−1 [brations , respectS–H gels . With thectively . These tectively . It was  in GBFS . The disGBFS [−1 , which b− permeability. The formation of hydration products gradually occupied the water space in the hydration-hardened slurry, dividing the space into irregular pores. The pores in the hardened slurry can be divided into micropores (<2 nm), mesopores (2–50 nm), and macropores (>50 nm) [(>50 nm) . Mesopor(>50 nm) ,33. The Based on the porosity of hardened paste under the different ASR-to-DG ratios in The micromorphology of paste pieces with different ASR-to-DG ratios at 180 days is shown in To investigate the difference in C–S–H gels between four pastes, fifty points were selected in areas A, B, C, and D of − needed to accelerate the dissolution of GBFS, which was confirmed by the Si–O–Al bond being broken in 2+ and SO42− provided by BOFS and DG, C–S–H gels and ettringite were generated to provide the strength source [− in the system; with the alumina octahedron provided by GBFS, Friedel’s salt was generated as Equation (2) [The hydration mechanism of BOFS–GBFS-based binders with DG addition has been described previously ,36. The h source ,38. The tion (2) : 4Ca2+ +42−, Cl− also reacted with alumina octahedron. Therefore, there is a competition between SO42− and Cl− that was impacted by the increase of ASR content. The generation of ettringite and Friedel’s salt could reveal this competition. Although the low solubility of ettringite provided a higher reaction possibility of SO42−, this competition was still influenced by ASR content. With an increase in the ASR content, the total formation of Friedel’s salt and ettringite increased according to the Al–O–H bond becoming sharper in FTIR spectra. However, Friedel’s salt increased with the slight decrease of ettringite based on the XRD and FE–SEM analyses.Similar with SO− in the system. At the beginning of the hydration, calcite could provide nucleation sites to form C–S–H gels [− reacting with alumina octahedra could provide silica tetrahedra to participate in the generation of C–S–H gels. However, the increase of ASR slightly decreased the generation of C–S–H gels according to the FTIR spectra in The formation of C–S–H gels was also affected by the addition of ASR content. The content of ASR introduced calcite and ClS–H gels . The GBF−.The porosity of concrete was one of the most fundamental factors that influenced the chloride penetration process ,40,41. T− to form Friedel’s salt and C–S–H gels capturing Cl−. The FTIR results in − penetration. Besides, the low ASR binder also formed a slightly higher C–S–H gel content to capture Cl−. Therefore, the chloride-binding capacity decreased with the increase of ASR content, as illustrated by the chloride profiles.Furthermore, the chloride-binding capacity also affected the chloride penetration . The bin− in solution according to the electric flux increase.The influence of ASR on the two chloride-resistance capacity methods was slightly different. Based on chloride profiles, the apparent chloride diffusion coefficient of the concrete met the changing pattern of pores larger than 10 nm. It can be stated that the penetration of high-concentration chloride solution was mainly affected by the pore structures. However, under an external source, chloride introduced by ASR may participate in the transportation of Cl− intrusion, Friedel’s salt’s formation might have occurred in the pores and caused crystallisation pressure, which was responsible for the strength decrease [The porosity of binders reduced first, then increased as the ratio of ASR to DG increased. Also, the proportion of 10–50 nm pore size, which affected strength and permeability , also dedecrease . TherefoThis paper focused on the influence of ASR on the strength and chloride-resistance capacity of BOFS–GBFS-based concrete. The mechanism of strength change and electric flux was also discussed using XRD, FTIR, MIP, and FE–SRM analyses.The addition of ASR strongly affected the early strength of the concrete. After 180 days’ curing, the strength of the concrete showed a similar lever of 73 MPa. With the immersion into high-concentration artificial seawater, the strength of the concrete decreased at a high and low ASR content, while concrete with the ASR-to-DG ratio of 2:3 and 3:3 presented strength improvement. The electric flux of the concrete increased with the rising ASR content. Due to the pore structure caused by extending the curing time, the electric flux decreased gradually.Like the BOFS-GBFS-based binders without ASR, the mainly hydrate product included ettringite and C–S–H gels. The increase in ASR content improved Friedel’s salt generation and slightly decreased the amount of ettringite. The total amount of them increased at the same time. Meanwhile, the formation of C–S–H gels also decreased slightly. But the mechanical properties of C–S–H gels achieved a maximum at a 3:3 ASR-to-DG ratio due to the highest Ca/Si ratio.−, the crystallisation pressure of Friedel’s salt was responsible for the strength loss at low and high ASR content.The ASR content had both positive  and negative (due to the formation reduction of C–S–H gels) influence on the paste porosity and pore structure. The improvement of ASR content decreased the chloride-binding capacity of the concrete. The influence of ASR content on the two chloride-resistance capacity measurements was different. Da was mainly affected by the pore percentage that was larger than 10 nm. However, the electric flux decreased with increasing ASR content. Besides, due to the higher bound ClThe introduction of ASR to a BOFS–GBFS-based cementitious system extended the range of solid as an activator. With considerable chloride-resistance capacity and strength performance in a high-chloride environment, the utilization of concrete containing ASR was improved. Therefore, economic and environmental benefits due to the utilisation of ASR, BOFS, GBFS, and DG include reducing cement demand, decreasing solid waste stockpiling, and preventing soil and water solution.


However, to apply geopolymer in concrete, it is critical to understand the compatibility between the coarse aggregate and the geopolymer binder. Experimental studies were conducted to explore the effect of the size of the coarse aggregate on the mechanical properties and microstructure of a metakaolin-based geopolymer (MKGP) concrete and ordinary concrete. Three coarse aggregate size grades  were adopted to prepare the specimens. The microstructure of the concretes was investigated with scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) and mercury intrusion porosimetry (MIP). Results showed an opposite coarse aggregate size effect between OPC and MKGP specimens in terms of compressive strength. SEM/EDS analysis indicated that the MKGP concrete has a weaker microstructure compared to OPC concrete induced by a higher porosity. The differences in mechanical properties and pore structure between the MKGP and OPC concrete are attributed to the greatly differing shrinkages triggered by the large surface area and penny-shaped particles of metakaolin. The findings in this work help tailor the mechanical properties and microstructure of MKGP concrete for future engineering applications.Geopolymer binders are a promising alternative to ordinary Portland cement (OPC) because they can significantly reduce CO Research on the use of fly ash, slag, silica fume, and metakaolin, as a source of aluminosilicate, has been increased [Ordinary Portland cement (OPC) concrete is the most widely used and essential material for most construction industries. Yet, its production leads to several environmental issues such as the depletion of natural raw materials including limestone and clay as well as air pollution . Moreove warming ,4. These warming  and it e warming ,7, resis warming , and exc warming . Geopolyncreased . Metakaoncreased . MK imprncreased .Concrete is a quasi-brittle material. It is important to study mechanical parameters comprehensively. Mechanical parameters include, in particular, compressive strength, tensile strength, modulus of elasticity, and fracture energy . The perHowever, the majority of the early studies on the geopolymer focused on the mortar and paste. Numerous investigations have been conducted on the influence of various parameters on geopolymer concrete (GPC), such as alkali precursor (such as fly ash) ratio, Si/Al ratio, alkali concentration, and the properties of the coarse aggregate ,23. The Even though intensive studies are performed on various fronts, for the construction industry use of MKGP concrete, a lot of research, regulation, and systemization demands to be accomplished. The above-mentioned studies have shown that the microstructure of the OPC concrete varies depending on the size of the coarse aggregate, which influenced its mechanical properties. Besides, the previous studies on GPC concrete mainly focused on the coarse aggregate content and properties rather than the size. As these properties considerably affect the OPC concrete performance and durability, therefore, it is imperative to extend the literature to study the effect of the size of the coarse aggregate on the MKGP concrete strength and microstructure where, to the best of our knowledge, it has not been investigated. It is still a matter of debate, and much work on the investigation of the effect of the coarse aggregate size on the mechanical properties and microstructure of MKGP concrete remains to be performed. Although most of the previous studies on the mechanical behavior of geopolymer concrete were conducted under elevated temperature conditions, this study reports the findings obtained under ambient temperature, which is the practical application condition.An experimental study was therefore conducted to investigate the effect of the coarse aggregate size on the mechanical properties of the MKGP concrete. The failure mode, compressive strength, splitting tensile strength, scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) analysis, and pore structure characterizations were employed to evaluate the MKGP concrete strength performance. The results were compared with the OPC concrete to present the implications for potential engineering applications. These findings help better understand the effect of the coarse aggregate size on GPC properties.2, Al2O3, and Fe2O3 content was 95.46%. This is above the minimum value of 70% as required by ASTM C618 [3. The standard sieves were employed to prepare the three groups of coarse aggregate, as shown in Typical OPC concrete specimens were prepared using the cement of CEM I 42.5 N . The indSTM C618 . FurtherThe concrete mixes with a grade of 40 MPa compressive strength at 28 days were prepared based on 5–10 mm coarse aggregate size, as summarized in Three concrete cubes with the dimensions of 150 mm × 150 mm × 150 mm and 100 mm × 100 mm × 100 mm were made for each group to measure the splitting tensile strength  SEM/EDS instrument was used at the 5- or 8- or 10-kV accelerating volt (FEI) model. The interfacial regions between the paste and the coarse aggregate were studied through microstructural investigations of the ITZ area in the specimens of the OPC and MKGP concrete considering the size of the coarse aggregate. Moreover, the mercury intrusion porosimeter  test was employed to determine the porosity and pore size distribution of the tested specimens.The average compressive strength test results of OPC concrete and MKGP concrete are presented in The MKGP concrete results yielded a decrease in compressive strength values as the coarse aggregate size increased. The results are consistent with the study by Guades , showingThe larger volume of the paste between the larger coarse aggregate leads to a more pronounced difference between the elastic modulus of the coarse aggregate and paste as a result of the increased coarse aggregate volume relative to the specimen volume . ConsequPhysically, the small surface area could result in the lower development of the gel bond, and consequently, increases the shrinkage cracks near the coarse aggregate. Moreover, the possible internal bleeding underside of a larger coarse aggregate could contribute to decreasing the splitting tensile strength by reducing the interfacial bond strength inside the concrete.Results show that the decrease of the Mechanical test results manifest the different microstructure behaviors of the MKGP concrete compared with the OPC concrete. Moreover, the development of the interfacial bond may vary in the MKGP concrete with different coarse aggregate sizes compared to the OPC concrete. This effect, however, is more pronounced in OPC concrete, probably due to relatively better compatibility between the OPC and coarse aggregate phases as compared to MKGP.Compressive strength and splitting tensile strength are essential material properties of the concrete to determine the design purposes and structural behavior of the concrete member. In addition, the tensile strength of the concrete could be estimated from its compressive strength. In this study, new empirical equations are therefore proposed to link the compressive and splitting tensile strengths of MKGP concrete and OPC concrete by considering the coarse aggregate size effect.To predict the compressive strength of concrete by considering the coarse aggregate size effect, Jiang et al.  proposedThe designed compressive strength ft=φHygrated Ca silicate;Hydrated Ca aluminate.In general, increasing the coarse aggregate size did not exhibit any considerable influence on the EDS analysis in this study, as shown in The Ca atoms’ intensity decreased from a concrete paste into the coarse aggregate, indicating the percentage of CH particles on the paste side is mainly responsible for the porosity in the ITZ . Si and The porosity and pore size distribution of the OPC and MKGP concrete specimens were obtained using MIP tests. The specimens tested by MIP in this study contain pores with distinct size ranges, one being micropores (<1 µm) and the other being macropores (>1 µm). Noticeable pore structure change could be observed from the presented data. Unlike the average pore results, the total porosity, macropore porosity, and total pore area in MKGP specimens are higher than in the OPC specimens. It shows that the pore structure significantly resulted in a change of the mechanical properties of the MKGP specimens.The mercury intrusion porosities of OPC1, OPC2, OPC3, MKGP1, MKGP2, and MKGP3 are 20.49%, 21.05%, 20.70%, 22.78%, 24.77%, and 23.11%, respectively. Although the results show that the effect of the coarse aggregate size is insignificant on the total porosity of the specimens, the MKGP concrete specimens’ porosities are higher than the OPC concrete specimens. For the MKGP concrete specimens, the macropore porosity results indicated that the larger coarse aggregate size resulted in a larger macropore porosity compared to OPC concrete, which consequently could lead to a decreased compressive strength of the MKGP concrete specimens.Compared with OPC concrete cubes, a visual inspection of the MKGP concrete cubes’ surface before the compression test showed more visible and finer cracks, as shown in Moreover, the central core of the OPC concrete cubes was relatively undamaged compared to the MKGP specimens. As the size of the coarse aggregate increases in the OPC concrete, the continuous crack growth could be delayed due to the confinement stresses because of the friction between the platens of the testing machine and the concrete cubes . It can The coarse aggregate could significantly influence the characteristics of concrete, as it occupies 70–80% of the concrete volume . It is rSEM observations confirmed the non-uniform microstructure of the MKGP paste compared to that of the OPC concrete. It may be because, in geopolymer production, the water is not combined directly with the gel product; accordingly, a small amount of the water remains as interstitial water in the gel . MoreoveThe observed pore structure measurements change in MKGP concrete could be attributed to its higher shrinkage, which yielded a porous structure in the MKGP specimens. The study of Yang, Zhu and Zhang  on geopo(1)The compressive strength of MKGP concrete and OPC concrete decreased and increased, respectively, as the size of the coarse aggregate increased. This behavior can be explained by the higher shrinkage of the MKGP concrete.(2)The maximum reduction and increment in compressive strength due to the increase of the size of the coarse aggregate of OPC concrete and MKGP concrete were 13% and 36%, respectively.(3)The splitting tensile strength decreased in both groups because coarse aggregates with larger sizes yield higher microcracks in the vicinity of the coarse aggregate.(4)The maximum reduction in the splitting tensile strength due to the increase of the size of the coarse aggregate of OPC concrete and MKGP concrete were 28% and 114%, respectively. (5)SEM/EDS investigations revealed that the size of the coarse aggregate does not significantly affect the ITZ area in this study. MIP results showed a larger pore diameter with increasing size of the coarse aggregate. The role of paste between coarse aggregates is therefore more pronounced as the size of the coarse aggregate increases.(6)It can be concluded that the changes in pore structure with the size of the coarse aggregate significantly influences the strength development of the tested specimens. An increase in the size of the coarse aggregate results in a higher shrinkage of MKGP concrete and subsequently results in a larger number of macropores. Hence, the influence of macropores is significant.This study investigates the effect of the coarse aggregate size on the mechanical properties of the MKGP concrete and OPC concrete. The compressive strength and splitting tensile strength of the specimens were determined after 28 days and were analyzed. From the results of the experimental work conducted in this study, the following conclusions can be drawn:


Immunoglobulin G (IgG) concentration is high in goat colostrum, particularly in the first few hours after parturition, and this is important for the kid’s immunity and growth. IgG levels vary depending on several factors, including breed, disease status, colostrum management, handling, and collection time postpartum. A handheld optical refractometer, an affordable instrument that is simple to use in the field, is used widely in dairy farms to measure total solids. However, it can also be applied to estimate colostrum IgG content on the basis of comparison with standard measurement methods, usually radial immunodiffusion. Studies comparing %Brix values in relation to IgG concentration measured using enzyme-linked immunosorbent assay (ELISA) in goats are limited. The present study aimed to evaluate the use of a handheld optical Brix refractometer for the measurement of IgG concentration in goat colostrum, compare results with those using ELISA, and estimate the %Brix cutoff value equating to low-quality colostrum.Colostrum samples were collected on day 0 from 21 goats  and were frozen. Subsequently, they were analyzed for IgG concentration using a goat-specific ELISA test and Brix percentage using a handheld refractometer. The optimum %Brix cutoff value for the evaluation of colostrum quality was evaluated.The mean IgG concentration and %Brix in colostrum were 10.60±0.64 mg/mL and 25.0±0.9, respectively. There was a significant (p<0.01) correlation between %Brix and IgG concentration. For an IgG concentration of 6.9 mg/dL, the cutoff value for %Brix was 18.5, equating to high specificity (100%) but low sensitivity (50%). A higher %Brix cutoff value of 21.5 showed high specificity (95%) and high sensitivity (100%).A Brix refractometer can be used to estimate goat colostrum quality with a proposed %Brix cutoff value of <18.5%-21.5% for poor-quality colostrum. For a few days postpartum, mammalian milk contains high concentrations of nutrients and immunological factors, including immunoglobulin G (IgG), which is essential for newborns. In many breeds of goat, the level of IgG in colostrum has been found to be high, rapidly declining within the 4 days after parturition. As measured using enzyme-linked immunosorbent assay (ELISA), the concentrations of IgG have been shown to decrease in Murciano-Granadina and Majorera goats ,2. Our pAs thestandard method  of measurement of IgG is difficult and time consuming, the use of a Brix refractometer has begun to be introduced as a more practical way to estimate IgG in the field. Brix refractometer is used to measure the percentage of sucrose in liquids, especially in agricultural products. The equipment is cheap, produces rapid results, and is practical for farm use. The associations between values obtained from Brix or refractometer and levels of IgG in colostrum of sows have been reported previously ; ruminanThe aim of this study, then, was to evaluate the feasibility of using a handheld optical Brix refractometer to estimate goat colostrum quality, as determined using IgG content measured through ELISA.The study was approved by Animal Care and Use Committee, Faculty of Veterinary Science, Chulalongkorn University (Protocol No. 1831051).The study was conducted from June 2018 to June 2019 at the Chaipattana Foundation’s Black Bengal Goat Domestication Project, Chiangrai Province, Thailand.®, Betagro, Bangkok, Thailand) containing 92.01% dry matter and chemical composition of 17.6% crude protein, 4.52% fat, and 14.8% crude fiber per dry matter basis. The roughage including chopped fresh Napier grass  and Pangola hay  was also given by 3 kg/head/day with the ratio of 2:1 (w/w). All goats were given free access to water. The routine vaccination against foot-mouth disease and the blood collection for negative results of lentivirus (CAE) and brucellosis were routinely performed once a year. The endoparasite was controlled using a variety of antiparasitic agents such as ivermectin and clorsulon , closantel , and niclosamide  which were rotational prescribed every 2-3 months. The ectoparasite was controlled twice a year using moxidectin  Pty. Ltd., NSW, Australia).Twenty-one dams, including nine BB, six SA, and their six crossbreds were housed in a conventional open housing system and were mated naturally with either SA or BB bucks. The temperature and relative humidity inside ranged from 14.6 to 32.8°C (mean±SD=26.1°C±4.5) and 42-91% (70.5°C±13.1), respectively. Goats were fed 200 g/head/day (07:00 and 18:00 h) with concentrate  were determined using infrared spectrophotometry . IgG concentration was determined by a goat-specific IgG ELISA kit  following the manufacturer’s instructions. After thawing, approximately 0.3 mL of colostrum sample was used for %Brix value determinations using a handheld optical Brix refractometer .® version 12.0. . Results are presented as mean±standard deviation. The relationships between %Brix values and other variables  were analyzed using Pearson correlation, whereas, for the relationship between %Brix and IgG concentration (ELISA results), simple linear regression was performed. The test performance  were calculated using IgG values measured through ELISA as the standard test. An ELISA IgG level of 6.9 mg/mL was selected as the threshold according to the value of the 10th percentile in this study. The receiver operating characteristics (ROC) curve and the area under the curve (AUC) were calculated to estimate the quality of the cutoff points. A probability value of <0.05 was considered statistically significant.Data were processed using SigmaPlotColostrum samples were collected from a total of 21 does, nine BB, six SA, and six crossbreed offspring (BB×SA), whose characteristics are shown in The cutoff value for an IgG concentration equating to good-quality colostrum was set at 6.9 mg/mL. The AUC for the %Brix readings from the ROC curve was 0.987 (p=0.027) . The cutst day colostrum enhanced gastrointestinal development and reduced mortality in calves compared with those receiving transition milk or plain milk [An association between newborn growth rate and IgG content in serum of neonate has been shown in ruminants, such as calves and buffaloes ,6. Consuain milk . Therefoain milk ,21, %BriRefractometers have been used for measuring the specific gravity (colostrometer), TS (%Brix), and refractive index (nD) and have been introduced to estimate IgG content in the colostrum of many species ,14-18. TMean IgG values in the present study were 10.6±0.6 mg/mL , similar to those in a previous study . The meaIn the present study, the mean±SD and range of %Brix values in colostrum were, respectively, slightly higher and narrower  than those in a previous study in goats , ruminanThe area under the operating curve in this study was 0.987 at the cutoff point of <6.9 mg/mL IgG as determined through ELISA and %Brix. In cows, the threshold of IgG for poor-quality colostrum as determined through both RID and ELISA was given as 50 mg/mL corresponding to cutoff points for %Brix at 23% , 22% 2121, 21% , 19.3% , and 18%In our study, the %Brix cutoff threshold value is 18.5. At this point, the specificity was 100% with high accuracy (95.2%), but low sensitivity (50%). The low sensitivity was due to the limited sample size. High values for NPV and PPV suggested that good-quality colostrum would not be discarded. A cutoff value of <21.5 provided a sensitivity of 100% and a specificity of 94.7%. Although the accuracy is similar to that of a cutoff at <18.5, a lower PPV of 66.7% suggests that some good colostrum may be categorized as poor and be discarded. Thus, the appropriate cutoff point would be 18.5% at this farm. A previous study suggested that the optimal cutoff point for %Brix in goats was 20.7 equating to 53.5% sensitivity and 100% specificity . DiffereThe present study showed a relationship between %Brix and fat content. It has been demonstrated previously that the fat influenced Brix value positively  and may A relatively small sample size was used in this study to calculate the cutoff value for %Brix, and this may have affected specificity and sensitivity. Moreover, other factors such as breed, the season of kidding, litter size, and parity of dam that affect the IgG levels  were notA Brix refractometer is an acceptable tool for evaluating poor-quality colostrum. A %Brix value of <18.5 in colostrum collected within 3 h of parturition was used as the cutoff value for poor-quality colostrum for goats on the farm used in this study.CB, ST, and KK: Contributed to the conception and design of the study, performed the statistical analysis, and wrote the manuscript. CB and SS: Contributed to data collection and laboratory analysis. MN and KK: Revised the manuscript. All authors read and approved the final manuscript.