CEMENT AND CONCRETE RESEARCH
·
2025
·
IF 13.1
Haochuan Wang,Xin Liu,Chong Wang,Wei Wang,Jinxiang Hong,Pan Feng
Ultra-early mechanical properties are critical for shotcrete performance, significantly influenced by ettringite and calcium silicate hydrate (C-S-H) formed during the initial hydration stage and free water. This study investigates the individual and synergistic effects of these phases on mechanical behavior using equivalent cement pastes. In this system, cement was entirely replaced with dolomite particles of matching size distribution, with the controlled introduction of free water, ettringite, and C-S-H. The validity of these equivalent systems was confirmed through comprehensive characterization. Mechanical performance was subsequently evaluated using compression, shear, Vickers hardness and nanoindentation tests. Results revealed that free water remarkably weakened the mechanical properties, whereas both ettringite and C-S-H enhanced strength by reducing voids and reinforcing weak particle interfaces. Ettringite primarily contributed to interparticle friction, while C-S-H enhanced cohesion at interfaces including dolomite-dolomite, dolomite-ettringite and ettringite-ettringite contacts. When co-existing, C-S-H formed within the porous ettringite network, not only establishing a multi-scale filling structure but also stabilizing the dolomite-ettringite skeleton. These findings advance our understanding of the early-age mechanical development of shotcrete and highlight the potential of equivalent cement systems as robust tools for research into cementitious materials.
研究领域:
土木工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
COMPOSITES PART B-ENGINEERING
·
2024
·
IF 12.7
Haochuan Wang,Pan Feng,Xin Liu,Jiashun Shi,Chong Wang,Wei Wang,Hua Li,Jinxiang Hong
The ultra-early age strength of shotcrete with Portland cement-based materials in various supporting constructions is crucial for safety and engineering efficiency. However, concerns exist about the low strength and uncertain mechanism when using aluminum sulfate, the main component of most-used alkali-free accelerators. This study addresses these concerns by introducing ettringite seeds into the Portland cement system with aluminum sulfate. Significant improvement in ultra-early age compressive strength of mortar, i.e., 242 % at 6 h and 201 % at 8 h, was achieved by mere 1 % seed addition. Analyses of hydration heat, composition and microstructure demonstrate that the ettringite seeds mainly affect the mechanical performance by forming a more prolonged and coarser ettringite skeleton, rather than directly accelerating cement hydration. Such an enhanced skeleton was proved to establish stronger interactions between particles in the Monte Carlo simulations. Additionally, the synergistic effect of the ettringite skeleton and C–S–H gel on ultra-early age strength was also explored. These proposed strengthening mechanisms were verified by the C 3 S and equivalent CaCO 3 systems.
研究领域:
土木工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2023
·
IF 7.4
Leyang Lv,Shitao Luo,Branko Šavija,Hongzhi Zhang,Lin Li,Tamon Ueda,Feng Xing
The particle size distribution (PSD) has a significant influence on the fresh and final properties of cement and its derived products. In this paper, CSA cements with three different mean diameters (D 50 ), ranging from 6.04 to 26.62 μm were prepared by milling. The pre-hydration behavior was quantitatively analyzed, including the degree of pre-hydration, the dynamic change of mineral assemblage and the morphology of the prepared CSA cement exposed to 57%, 75% and 97% relative humidities (RHs) for up to 90 days. Hydration kinetics, porosity, and compressive strength of the cement paste made with fresh and pre-hydrated CSA cement with different PSD were also characterized. The results show that pre-hydration of CSA cement at RH higher than 75% has detrimental effects on the hydraulic activity and strength gain of CSA cement. However, coarser CSA cement (D 50 = 26.62 μm) does not only show better resistance to pre-hydration, but also higher compressive strength and lower porosity.
研究领域:
材料科学
·
土木工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Sustainable Cement-Based Materials
·
2025
·
IF 4.2
Yimu Wang,Jinqing Jia,Dingming Zhang
The effect of low concentration (not exceeding 2%) calcium formate (CF) on the hydration process of tricalcium aluminate (C3A, Ca3Al2O6, the fastest hydrating component in cement)-gypsum systems was investigated in this study using methods such as isothermal calorimetry, XRD, TGA-DSC and SEM. Results demonstrate that a higher dosage of CF corresponds to a more pronounced enhancement in C3A hydration. Furthermore, CF inhibits the initial formation of hydrogarnet (C3AH6, Ca3Al2(OH)12) and promotes the formation of ettringite (AFt) in C3A-gypsum system at 2 h hydration. However, after 1 d hydration, CF facilitates the conversion of excess C3A to C3AH6, which delays the transformation of AFt to AFm. SEM observations reveal that the CF-induced reduction in the size of AFt crystals, formed during C3A hydration, facilitates their more effective filling of interstitial voids within the hydration products, thereby contributing to the formation of a more resilient interlocking structure.
研究领域:
材料科学
·
水泥化学
·
无机非金属材料
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建筑材料
·
水化动力学
✓ 已验证
产品关联
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2024
·
IF 7.1
Xiangshan Hou,Jingwei Li,Jianwei Xu,Xin Xiao,Jianyong Wang,Yanhui Liu,Mona Ossman,Fawei Lin,Xujiang Wang,Yuzhong Li,Wenlong Wang
Rapid repair mortar (RRM) is widely used to repair infrastructures, which must achieve high early strength and long-term service. This study investigated the influence of hot/wet harsh environmental conditions on RRM prepared using solid-waste-based sulfoaluminate cement (WSAC). Orthogonal experiments were conducted to obtain the optimized WSAC-based RRM. Then, the impact of simulated harsh conditions (cross-combination of 20/60 °C and 10/40/90%RH humidity) on RRM and synthetic ettringite was studied. High temperature and low humidity restrained the volume deformation and promoted the growth of the later-age compressive strength of the RRM, but reduced the flexural strength. In this case, ettringite lost some water molecules in the Ca–H2O groups and transformed into amorphous meta-ettringite, which retained its needle-rod morphology. A small amount of ettringite decomposed into gypsum, AH3, and Ca(OH)2 under high-humidity conditions, which caused a slight expansion and reduced the compressive strength of the RRM. Fortunately, most ettringite was well protected by the dense RRM matrix, and harsh temperature and humidity conditions could only slowly promote the transformation of ettringite in RRM over a long period. Therefore, short-term rain or hot weather has little effect on the mechanical properties of WSAC-based RRM. This study provides a theoretical basis and data support for the promotion of industrialization of WSAC-based RRM, which is in line with the concept of green and sustainable development.
研究领域:
土木工程
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材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
Materials
·
2025
·Vol. 18
·期 15
·3436
·
IF 3.2
Nuo Xu,Rentuoya Sa,Yuqing He,Jun Guo,Yiheng Chen,Nana Wang,Yuchuan Feng,Suxia Ma
Circulating fluidized bed fly ash (CFBFA) stockpiles release alkaline dust, high-pH leachate, and secondary CO 2 /SO 2 —an environmental burden that exceeds 240 Mt yr −1 in China alone. Yet, barely 25% is recycled, because the high f-CaO/SO 3 contents destabilize conventional cementitious products. Here, we presents a pressurized flue gas heat curing (FHC) route to bridge this scientific deficit, converting up to 85 wt% CFBFA into structural lightweight gravel. The gypsum dosage was optimized, and a 1:16 (gypsum/CFBFA) ratio delivered the best compromise between early ettringite nucleation and CO 2 -uptake capacity, yielding the highest overall quality. The optimal mix reaches 9.13 MPa 28-day crushing strength, 4.27% in situ CO 2 uptake, 1.75 g cm −3 bulk density, and 3.59% water absorption. Multi-technique analyses (SEM, XRD, FTIR, TG-DTG, and MIP) show that FHC rapidly consumes expansive phases, suppresses undesirable granular-ettringite formation, and produces a dense calcite/needle-AFt skeleton. The FHC-treated CFBFA composite gravel demonstrates 30.43% higher crushing strength than JTG/TF20-2015 standards, accompanied by a water absorption rate 28.2% lower than recent studies. Its superior strength and durability highlight its potential as a low-carbon lightweight aggregate for structural engineering. A life-cycle inventory gives a cradle-to-gate energy demand of 1128 MJ t −1 and a process GWP of 226 kg CO 2 -eq t −1 . Consequently, higher point-source emissions paired with immediate mineral sequestration translate into a low overall climate footprint and eliminate the need for CFBFA landfilling.
研究领域:
环境工程
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材料科学
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土木工程
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碳捕集与利用
·
废弃物管理
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CEMENT & CONCRETE COMPOSITES
·
2022
·
IF 9.93
Cong Wu,Bing Yin,Dongshuai Hou,Shaochun Li,Xinpeng Wang
Core-shell polymer coating is a significant means of improving the surface protection of cement-based materials. In this paper, a novel strategy for the paraffin-doped polystyrene acrylate-polysiloxane core-shell emulsions (CSP) are proposed by combining polyaddition and polycondensation reactions , integrating the superior corrosion-resistance of PSA emulsions with the high-hydrophobicity of siloxane emulsions. The CSP emulsions have excellent physical stability and rheological behavior , with a lower proportion of unsaturated bonds and lower content of chemically bound water. The core-shell structure promotes the formation of Si–O bonds between the polymer molecules and the cement matrix , and more conducive to the formation of new silicate crystals on the cement hydrate surface. Macroscopically, the surface energy of the cement samples treated with CSP coating is below 16.7 mJ/m 2 , while its superficial nanoscale papillae give a water contact angle of almost 140°. The capillary absorption coefficient of the Portland concrete treated with CSP coating can be decreased to only 2.09 g/(m 2 ·h 0.5 ). Meanwhile, the corrosion rate of Cl − and SO 4 2− on the cementitious materials are significantly inhibited by the CSP membrane, reducing the levels of Friedel's salt, ettringite and gypsum generated by ionic corrosion, respectively. Furthermore, the CSP membranes have excellent molecular structural integrity and high cross-linkage under acid/alkaline corrosion and photo-thermal aging, maintaining superior adhesion and corrosion resistance with the cement substrate.
研究领域:
材料科学
·
土木工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）