Effect of pores and moisture on the mechanical properties of calcium silicate hydrate gels at mesoscale

IF 7.4 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Construction and Building Materials Pub Date : 2024-11-04 DOI:10.1016/j.conbuildmat.2024.138998

Zongli Li , Taotao Tong , Jiayue Shi , Yunlong Wang , Peng Jin

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Abstract

Pores and moisture significantly influence the mechanical properties of cementitious materials. Investigating the effects of pores and moisture on the mechanical properties of calcium silicate hydrate (C-S-H) gels at the mesoscale is fundamental to understanding the multiscale behavior of these materials. In this study, mesoscopic models of C-S-H gels with varying porosities were developed using coarse-grained C-S-H nanoparticles. The potential function, describing the interaction between C-S-H nanoparticles under different humidity conditions, was derived based on the mechanical properties of C-S-H nanoparticles, the Lennard-Jones (LJ) potential, and capillary theory. Subsequently, simulations of uniaxial tensile, uniaxial compression, and shear experiments on C-S-H gels with different porosities and moisture levels were conducted. The influence of pores and moisture on the mechanical properties of C-S-H gels was analyzed using two-way analysis of variance (ANOVA) and then compared with mesoscopic influence patterns. The results showed that the mechanical properties of C-S-H gels decrease with increasing porosity and moisture at the mesoscale. And there is an interaction effect between gel pore porosity and moisture. The smaller the porosity, the more significant the weakening effect of increasing moisture on elastic parameters and strength. Conversely, the weakening effect of increasing porosity on elastic parameters and strength is more significant at lower moisture levels. The interaction between pores and moisture has a more pronounced effect on strength, which intensifies with increased moisture. The effect of porosity on the mechanical properties of C-S-H gels is consistent with macroscale studies. However, the effect of moisture on elastic parameters exhibits an opposite trend, attributed to the different mechanisms of water's influence at different scales.

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孔隙和水分对中尺度硅酸钙水合物凝胶机械特性的影响

孔隙和水分对胶凝材料的机械性能有很大影响。在中观尺度上研究孔隙和水分对水合硅酸钙（C-S-H）凝胶力学性能的影响对于理解这些材料的多尺度行为至关重要。本研究利用粗粒 C-S-H 纳米粒子建立了不同孔隙率的 C-S-H 凝胶中观模型。根据 C-S-H 纳米粒子的机械特性、伦纳德-琼斯（LJ）电位和毛细管理论，推导出了描述不同湿度条件下 C-S-H 纳米粒子之间相互作用的电位函数。随后，对不同孔隙率和湿度的 C-S-H 凝胶进行了单轴拉伸、单轴压缩和剪切实验模拟。利用双向方差分析（ANOVA）分析了孔隙和水分对C-S-H凝胶力学性能的影响，然后与中观影响模式进行了比较。结果表明，在中观尺度上，C-S-H 凝胶的力学性能随着孔隙率和水分的增加而降低。凝胶孔隙率和水分之间存在交互效应。孔隙率越小，水分增加对弹性参数和强度的削弱作用越明显。相反，在湿度较低的情况下，增加孔隙率对弹性参数和强度的削弱作用更为明显。孔隙和水分之间的相互作用对强度的影响更为明显，这种影响随着水分的增加而加剧。孔隙率对 C-S-H 凝胶机械性能的影响与宏观研究结果一致。然而，水分对弹性参数的影响呈现出相反的趋势，这归因于水分在不同尺度上的影响机制不同。

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来源期刊

Construction and Building Materials 工程技术-材料科学：综合

CiteScore

13.80

自引率

21.60%

发文量

3632

审稿时长

82 days

期刊介绍： Construction and Building Materials offers an international platform for sharing innovative and original research and development in the realm of construction and building materials, along with their practical applications in new projects and repair practices. The journal publishes a diverse array of pioneering research and application papers, detailing laboratory investigations and, to a limited extent, numerical analyses or reports on full-scale projects. Multi-part papers are discouraged. Additionally, Construction and Building Materials features comprehensive case studies and insightful review articles that contribute to new insights in the field. Our focus is on papers related to construction materials, excluding those on structural engineering, geotechnics, and unbound highway layers. Covered materials and technologies encompass cement, concrete reinforcement, bricks and mortars, additives, corrosion technology, ceramics, timber, steel, polymers, glass fibers, recycled materials, bamboo, rammed earth, non-conventional building materials, bituminous materials, and applications in railway materials.