Construction and Building Materials最新文献

{"title":"Optimization of strength and durability properties of rubberized concrete mixtures containing silica fume using Taguchi method","authors":"Nouraldin Abunassar ,&nbsp;Mustafa Alas","doi":"10.1016/j.conbuildmat.2025.140455","DOIUrl":"10.1016/j.conbuildmat.2025.140455","url":null,"abstract":"<div><div>The present study aims to optimize the mixture design of rubberized concrete using the Taguchi method to enhance various performance parameters, including workability, compressive and flexural strengths, dry unit weight, water absorption, and resistance to sulfate and HCl acid exposure. Three primary control factors were investigated including silica fume, fine rubber, and coarse rubber. Each factor was evaluated at four substitution levels: 5 %, 10 %, 15 % and 20 % silica fume; 2.5 %, 5 %, 7.5 % and 10 % fine rubber; and 2.5 %, 5 %, 7.5 % and 10 % coarse rubber. A total of 16 mixtures were prepared and evaluated. The experimental results demonstrate the effects of these factors on concrete characteristics, with a focus on identifying optimal proportions that achieve enhanced mechanical strength and durability characteristics. Additionally, to maximize compressive strength, flexural strength, and resistance to sulfate and HCl attacks; the application of the Taguchi method proposed an optimized mixture design comprising 15 % silica fume, 2.5 % fine rubber and 2.5 % coarse rubber. The optimized mixture showed improvements in 28-day compressive strength, 56-day compressive strength, 28-day flexural strength, resistance to Na₂SO₄ and resistance to HCl of 4.55 %, 4.92 %, 5.34 %, 5.22 %, and 5.96 %, respectively.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140455"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interfacial bonding performance of CFRP sheet reinforced corroded steel plates under fatigue loading","authors":"Pu Zhang ,&nbsp;Haoxiang Li ,&nbsp;Ye Liu ,&nbsp;Xianghua Tao ,&nbsp;Yuanhao Qi ,&nbsp;Shamim Ahmed Sheikh","doi":"10.1016/j.conbuildmat.2025.140450","DOIUrl":"10.1016/j.conbuildmat.2025.140450","url":null,"abstract":"<div><div>Crucial research gaps remain in understanding the bonding performance of the CFRP-corroded steel interface under fatigue loading. This study investigated the interfacial bonding performance of Carbon Fiber Reinforced Polymer (CFRP)sheets and corroded steel plates under fatigue loading using double shear specimen tests. The analysis focused on the effects of multiple factors, including the steel plate corrosion rate and the ratio of the upper bound value (<em>P</em>_<em>max</em>) and lower bound value (<em>P</em>_<em>min</em>) of the fatigue loading to the debonding load (<em>P</em>_<em>u</em>). Specifically, <em>P</em>_<em>min</em>/<em>P</em>_<em>u</em> ranged from 0.1 to 0.3, while <em>P</em>_<em>max</em>/<em>P</em>_<em>u</em> ranged from 0.45 to 0.65. Notable findings include: (i) Under fatigue loading, the displacement at the tested end of the specimen increased progressively with more fatigue cycles,showing a nonlinear trend. This reflects cumulative interface degradation caused by adhesive plastic slip and micro-crack propagation, particularly at higher stress levels; (ii) The interfacial stiffness of CFRP sheet-corroded steel plate specimens weakened progressively during fatigue loading, particularly under high corrosion rates. A 15 % widening of the load-slip curve envelope at <em>P</em>_<em>max</em>/<em>P</em>_<em>u</em> = 0.45 indicated reduced load transfer efficiency and increased energy dissipation capacity as interface degradation accumulated.; (iii) Fatigue life was highly sensitive to load limits, particularly under high corrosion rates (15 %). Increasing <em>P</em>_<em>max</em>/<em>P</em>_<em>u</em> from 0.45 to 0.65 reduced fatigue life by 97 %, while increasing <em>P</em>_<em>min</em>/<em>P</em>_<em>u</em> from 0.1 to 0.3 extended fatigue life by 17 times, highlighting the critical role of stress amplitude control in fatigue performance.; (iv) At the same corrosion rate, the interface exhibited a reduced fatigue life as stress levels increased, and specimens with different corrosion rates demonstrated a shorter fatigue life compared to uncorroded ones. A method for predicting the fatigue life of the CFRP-steel interface was proposed, taking into account the influence of corrosion rate and load level, with a prediction equation derived using Lagrange polynomial fitting for corrosion rates ranging from 0 % to 15 %,with a prediction error below 8 %. Rarely seen in previous studies, this method offers valuable insights for evaluating the durability of CFRP-reinforced structures and guiding the maintenance of aging infrastructure in corrosive environments.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140450"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative study of geopolymers synthesized with alkaline and acid reactants at various liquid-to-solid ratios using Moroccan kaolin clay","authors":"Hajar Dihaji ,&nbsp;Dounia Azerkane ,&nbsp;Lahcen Bih ,&nbsp;Abderrahim Essaddek ,&nbsp;EL Mehdi Haily","doi":"10.1016/j.conbuildmat.2025.140453","DOIUrl":"10.1016/j.conbuildmat.2025.140453","url":null,"abstract":"<div><div>This study explores the underutilized potential of Guenfouda kaolin as a raw material for geopolymer synthesis, addressing the gap in comparative analyses of acidic and alkaline activation methods. Geopolymers were synthesized using thermally activated natural kaolin (metakaolin) with sodium-based alkaline (NaOH and Na₂SiO₃) and phosphoric acid (H₃PO₄) activation methods, with a focus on the effect of varying Liquid-to-Solid (L/S) ratios (0.5, 0.6, 0.7, and 0.8). Raw materials and geopolymers were characterized by X-ray fluorescence (XRF), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), compressive strength testing, and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS). Characterization of the kaolin revealed its rich alumina and silica content, making it an ideal precursor for geopolymer synthesis. XRD analysis showed a broad amorphous bump without significant variation in the crystalline structure of geopolymers at different L/S ratios. FTIR spectroscopy findings revealed the presence of specific bands related to aluminosilicate networks in alkaline geopolymers and characteristic bonds associated with phosphosilicate networks in acid geopolymers. The mechanical performance results showed that the compressive strength of alkaline geopolymers reached a maximum of 28.25 MPa at an L/S ratio of 0.6, while that of acid geopolymers was 22.73 MPa at an L/S ratio of 0.8. Densification of the geopolymer structure is improved by increasing the L/S ratio, according to SEM images. This is particularly observed at optimal ratios, where homogeneous microstructures were noted in both types of geopolymer. This study advances the sustainable utilization of local kaolin, offering novel insights into optimizing geopolymerization processes for eco-friendly construction materials.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140453"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of three-dimensional aggregate contact evolution using an enhanced image segmentation algorithm","authors":"Zundong Liang ,&nbsp;Chao Xing ,&nbsp;Yiqiu Tan ,&nbsp;Bo Liu ,&nbsp;Wei Wang","doi":"10.1016/j.conbuildmat.2025.140371","DOIUrl":"10.1016/j.conbuildmat.2025.140371","url":null,"abstract":"<div><div>In aggregate skeleton structure research, the distribution of aggregate contact points is a key factor affecting structural stability under loading. However, traditional image segmentation methods struggle to accurately segment aggregates in CT images, making the study of aggregate contact in three-dimensional space in real specimens a challenge. To address this, this study first proposes an adaptive bilateral filtering algorithm for CT image preprocessing to enhance edge details. Then, an improved U-Net algorithm is proposed, which combines Inception convolution modules, residual connections, spatial attention mechanisms, and a novel loss function incorporating boundary information, effectively solving the adhesion issue in aggregate segmentation. Finally, based on the centroids and spatial orientation of aggregates, an approximate ellipsoid model is constructed, and the contact number of the main skeleton aggregates is calculated, further analyzing the evolution of contact numbers during loading.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140371"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preparation and performance improvement of municipal solid waste incineration bottom ash based geopolymer modified by self-extracted CaO","authors":"Zhikun Zhang ,&nbsp;Yuanqing Gao ,&nbsp;Yufei Xu ,&nbsp;Mengying Yun ,&nbsp;Boxiong Shen ,&nbsp;Jiao Ma ,&nbsp;Lina Liu","doi":"10.1016/j.conbuildmat.2025.140447","DOIUrl":"10.1016/j.conbuildmat.2025.140447","url":null,"abstract":"<div><div>In recent years, the conversion of municipal solid waste incineration bottom ash (MSWIBA) into geopolymer has attracted much attention. However, the properties of MSWIBA based geopolymers were limited by the absence of reactivity and active calcium. In this work, a novel method of preparing MSWIBA based geopolymers by adding CaO extracted from MSWIBA was proposed. The effects of thermally treated MSWIBA (TBA700) (10–90 wt%) and self-extracted CaO (B-CaO) (0–10 wt%) on the compressive strength, micro-morphology, pore structure, and heavy metal leaching of geopolymers were investigated. The phase transformation, property, molecular structure, micro-morphology, pore structure and heavy metal content of the geopolymers were characterized and tested using X-ray Diffraction (XRD), Thermo-gravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Mercury Infiltration Porosity (MIP) and Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). The results showed that the geopolymers prepared with the addition of B-CaO showed better properties due to the generation of more hydrate calcium silicate (C-S-H). The compressive strength of the geopolymers increased with the addition of B-CaO and TBA700. When the TBA700 content was increased to 30 %, the compressive strength of the geopolymers reached 9.21 MPa at 28 d. Furthermore, the addition of 5 % B-CaO resulted in the highest compressive strength of 23.36 MPa under the same curing conditions. All the prepared geopolymers showed the leaching concentrations of Cd, Cr, Cu, Zn, and Pb that were substantially below the regulatory limits set by GB18598–2019. Therefore, MSWIBA based geopolymers by adding its self-extracted CaO showed a promising strategy to improve the product properties and provided the foundation for the recycling of calcium-containing solid wastes into geopolymer.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140447"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insights into the hydration kinetics and microstructural evolution of ultra-high performance cementitious composite at mid-to-low curing temperatures","authors":"Fangyu Han ,&nbsp;Jialiang Wang ,&nbsp;Xuping Ji ,&nbsp;Shuohui Chen ,&nbsp;Jianzhong Liu ,&nbsp;Min Wu ,&nbsp;Jiaping Liu","doi":"10.1016/j.conbuildmat.2025.140403","DOIUrl":"10.1016/j.conbuildmat.2025.140403","url":null,"abstract":"<div><div>Strength insufficiency in ultra-high performance cementitious composites (UHPCC) during winter construction has attracted attention, yet the mechanisms underlying the impacts of mid-to-low temperatures on strength development remain unclear. This study systematically investigated the mechanisms underlying the early-age strength insufficiency of UHPCC within the temperature range of 5°C to 20°C. The effects of curing temperatures on hydration reactions, microstructural evolution, and mechanical strength were comprehensively analyzed. The results revealed that during the early hydration stage (0–3d), lower curing temperatures (5°C, 10°C) significantly reduced hydration reaction rates and the formation of hydration products, leading to lower matrix density and early strength compared to 20°C, demonstrating a pronounced thermodynamic response. With prolonged curing time (7–28d), lower temperatures, particularly at 5°C, facilitated the accumulation of hydration products and pore structure refinement, partially mitigating adverse effects of initial delays. Microscopic characterizations (SEM-EDS, TGA, FTIR, XRD) confirmed that low temperatures influenced the formation and transformation of critical hydration products such as C-(A)-S-H gel and Ca(OH)₂, while potentially inducing nano- and microscale structural defects in the material matrix. Hydration kinetics analysis indicated that UHPCC hydration rates were highly sensitive to temperature, with a reduction to 5°C lowering reaction rates by approximately 58.9 %. These complex hydration behavior of UHPCC contribute to the nonlinear decline in the strength development as temperatures decrease, with strength losses reaching as high as 31.8 % at 10°C. The findings provide scientific insights and practical guidance for optimizing UHPCC performance in real-world low-temperature construction environments.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140403"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Contribution of calcium-containing minerals on the mechanical properties of alkali-activated materials: A study of carbonation steel slag","authors":"Yang Liu ,&nbsp;Bingyang He ,&nbsp;Zhaohou Chen ,&nbsp;Xiaohuan Jing ,&nbsp;Daqiang Cang ,&nbsp;Yongchao Zheng ,&nbsp;Lingling Zhang","doi":"10.1016/j.conbuildmat.2025.140451","DOIUrl":"10.1016/j.conbuildmat.2025.140451","url":null,"abstract":"<div><div>Not only capture CO₂, the carbonated steel slag (CSS) can be used as supplementary cementitious materials to exhibit excellent physical and chemical properties. In order to understand the mineral phase evolution and hydration mechanism of CSS in alkali-activated materials (AAMs), the contribution of calcite and calcium-containing minerals (Ca-minerals) to the hydration degree was deeply investigated, and the microstructure and mechanical properties of AAMs were explored. The results showed that AAMs prepared by CSS exhibited stronger early mechanical properties and lower drying shrinkage than AAMs prepared by steel slag (SS). The compressive strength of AAMs prepared by 30 % CSS and 70 % fly ash was 54.2 % greater than that of AAMs prepared with SS in the same conditions. The EDS test suggested that the carbonation product calcite possessed a higher specific surface area and provided more nucleation sites. Both calcite and Ca-minerals could provide Ca^2 + into the silica-aluminate network. The decomposition reaction rate of calcite stabilized at around 30 % when FA was incorporated in paste, and the remaining calcite could fill the pores to improve the strength. Interestingly, 87.6 % of calcite mainly produced pirssonite when only CSS existed in paste. Besides, the Ca-minerals (srebrodolskite, brownmillerite, and all mayenite) in CSS possessed higher reactivity compared with SS, and underwent rapid decomposition under alkali activation conditions. Carbon footprint analysis showed that AAMs prepared with CSS resulted in the lowest carbon emission of 308.4 kg CO₂-eq, providing a novel approach for the application of CSS.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140451"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revealing aging behavior retarding mechanism of zinc oxide/expanded vermiculite composite modified bituminous mixture","authors":"Haihui Duan ,&nbsp;Henglong Zhang ,&nbsp;Songtao Lv ,&nbsp;Weiwei Lu ,&nbsp;Dongdong Ge ,&nbsp;Ruiyao Jiang ,&nbsp;Jinping Wang","doi":"10.1016/j.conbuildmat.2025.140388","DOIUrl":"10.1016/j.conbuildmat.2025.140388","url":null,"abstract":"<div><div>Zinc oxide/expanded vermiculite composite (ZnO/EVMT), a novel modifier, can synergistically improve the thermal oxidative and ultraviolet (UV) aging resistance of bituminous mixture. However, the existing characteristics of ZnO/EVMT and the recovered binder in mixture is unclear, preventing the understanding of its aging behavior retarding mechanism. In this research, the modified bituminous mixture was prepared and treated with four aging methods, including short-term and long-term oven aging, long-term continuous and holoclimate UV aging. The ZnO/EVMT and bituminous binder in the aged mixtures were recovered. Then, the microscopic and thermodynamic characteristics of the recovered ZnO/EVMT and the retarded aging behavior of the recovered binder were characterized. Finally, the aging behavior retarding mechanism of ZnO/EVMT modified bituminous mixture was revealed. Results show that the recovered ZnO/EVMT can maintain the integrity of its original structure in both bituminous binder and mixture, and is distributed on the bitumen film surface of the loose mixture. ZnO/EVMT modified bitumen forms an exfoliation phase structure, enhancing bitumen heat barrier effect. The incorporation of ZnO/EVMT into bituminous mixture can reduce the production of carbonyl or sulfoxide group contents and the increment of large-size molecule content under different aging methods. The aging behavior retarding mechanism lies in the two-dimensional layered structure of its EVMT component and the semiconductor characteristics of its ZnO particle component, as well as the synergistic effect between the two components. Therefore, it can be expected that the mechanism by which ZnO/EVMT retards mixture aging behavior is beneficial not only for regulating its own performance and promoting its application but also for extending the expected service life and enhancing the durability of bituminous pavements.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140388"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preparation and performance study of PPA-REOB composite modified bitumen","authors":"Dedong Guo ,&nbsp;Shihua Yang ,&nbsp;Meng Xu ,&nbsp;Xiang Li ,&nbsp;Xupeng Sun ,&nbsp;Teng Wang ,&nbsp;Yutong An ,&nbsp;Sha Huang","doi":"10.1016/j.conbuildmat.2025.140361","DOIUrl":"10.1016/j.conbuildmat.2025.140361","url":null,"abstract":"<div><div>To efficiently REOB and address the technical challenge of improving the low-temperature performance of PPAMB, this study investigates the preparation and performance of composite modified bitumen using REOB and PPA as additives. The micro-mechanisms and macroscopic properties of the composite modified bitumen were systematically studied. First, the optimal contents of REOB and PPA were determined based on fundamental performance indicators. Second, the modification mechanisms of REOB and PPA on bitumen were revealed through micro-analysis techniques, including XRF, SARA fractionation, infrared spectroscopy, and FM. Third, the effects of PPA and REOB on the macroscopic performance of bitumen were evaluated using DSR, BBR tests, and adhesion tests. Finally, the macro-level road performance of PPA-REOB MB mixtures was compared with PPAMB mixtures to validate the findings. The results indicate that the optimal contents of PPA and REOB are 0.5 % and 1.8 %, respectively, yielding the best fundamental indicators for PPA-REOB MB. REOB can disperse and solubilize heavy fractions in bitumen, primarily promoting the transition of the bitumen system to a sol structure through physical interactions. This significantly enhances the low-temperature performance of PPAMB, reducing its stiffness modulus (S) at −6°C by 26.4 % and increasing its creep rate (m-value) by 12 %. However, REOB also slightly decreases the high-temperature performance of PPAMB, with a 19.97 % reduction in rutting factor at 76°C and a 1.55 % increase in phase angle, although the performance remains notably superior to that of matrix bitumen. Furthermore, the adhesion rate of PPA-REOB MB improves by 14.13 % compared to matrix bitumen but decreases by 5.5 % compared to PPAMB. PPA-REOB MB mixtures exhibit significantly better low-temperature performance than PPAMB mixtures, although with a slight reduction in high-temperature performance.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140361"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"AC impedance spectroscopy interpretation of the hydration behavior for cement mortar containing fly ash and nano-metakaolin","authors":"Qiuchao Li ,&nbsp;Yingfang Fan ,&nbsp;Yulong Zhao ,&nbsp;Hao Chen ,&nbsp;Surendra P. Shah","doi":"10.1016/j.conbuildmat.2025.140436","DOIUrl":"10.1016/j.conbuildmat.2025.140436","url":null,"abstract":"<div><div>The partial replacement of cement with fly ash (FA) has the potential to reduce industrial waste and carbon emissions. FA-cement systems exhibit lower strength during the early hydration period, which limits their applications. Nano-metakaolin (NMK) is known to enhance early strength, yet its effect on the hydration and microstructure development of FA cement systems remains unclear. This study utilizes the alternating current impedance spectroscopy (ACIS) method to investigate the hydration properties and microstructural evolution of NMK/FA cement mortar. The suitability of the ACIS method was validated through the use of TGA, XRD, and MIP tests. A suitable equivalent circuit model <em>R</em>_s(CPE₁(<em>R</em>_ct1<em>W</em>₁))(CPE₂(<em>R</em>_ct2<em>W</em>₂)) was determined to analyze the ACIS data. Furthermore, the relationships between strength and ACIS parameters of NMK/FA cement mortar were established. The results indicate that NMK promotes the formation of hydration products and refines the pores of FA cement paste, particularly during the 7–14 d. The ACIS observations are consistent with the conclusions derived from XRD and TGA. FA decreases the bulk resistance of cement mortar, whereas NMK significantly increases it, especially during the 7–14 d period. A synergistic pozzolanic reaction between NMK and FA occurs within the 7–14 d period, which is crucial for the long-term performance and durability of NMK/FA cement systems. When 5 % NMK is added to the cement paste with 30 % FA, the pores larger than 1 μm significantly decrease. Compared to FA30N0, the compressive strength of FA30N5 cement mortar increased by 12.9 %, 35.4 %, 20.0 %, and 8.3 % at 3, 7, 14, and 28 d, respectively. Furthermore, a logarithmic relationship exists between compressive and flexural strengths, the diffusion impedance coefficient and the bulk resistance of the NMK/FA cement mortar.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140436"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}