溶蚀水泥浆弹性模量预测的分步解析法

摘要/Abstract

摘要： 在低碱度环境中混凝土内部钙离子的溶出是引起混凝土内部孔隙率显著增大,进而使力学性能减退的重要原因。为深入研究水泥浆溶蚀后弹性模量的退化规律,建立了一种预测溶蚀水泥浆弹性模量的分步解析法。首先将水化水泥颗粒视作由未水化水泥颗粒(UC)、高密度水化凝胶(H-HL)和低密度水化凝胶(L-HL)组成的三相复合球,通过引入由UC和H-HL组成的等效夹杂相(EQ),三相复合球模型就可以简化为由夹杂相和L-HL组成的等效水化水泥颗粒模型,最后利用弹性理论求解由等效水化水泥颗粒和溶蚀水泥浆孔隙率组成的两相复合球弹性模量。通过对比第三方数值结果,验证了分步解析法的有效性。基于本文建立的解析方法,分析了水化度、氢氧化钙(CH)与水化硅酸钙(C-S-H)的体积比、高密度水化硅酸钙(C-S-H_a)与低密度水化硅酸钙(C-S-H_b)体积比三个重要参数对溶蚀水泥浆弹性模量的影响。本研究给出了水泥浆溶蚀后弹性模量退化的解析方法,可为混凝土钙溶蚀后的耐久性设计提供一些参考。

关键词: 水泥浆, 钙溶蚀, 弹性理论, 复合球模型, 分步解析法

Abstract: The leaching of calcium ions from the interior of concrete in a low alkalinity environment is an important factor causing a significant increase in the internal porosity of concrete, leading to a deterioration in its mechanical properties. In order to investigate the degradation law of the elastic modulus of cement paste after calcium leaching, this paper establishes a step-by-step analytical solution for predicting elastic modulus of leached cement paste. Firstly, the hydrated cement particles are regarded as a three-phase composite sphere composed of unhydrated cement particles (UC), high-density hydrated gel (H-HL), and low-density hydrated gel (L-HL). By introducing an equivalent inclusion phase (EQ) composed of UC and H-HL, the three-phase composite sphere model can be simplified into an equivalent hydrated cement particle model composed of the inclusion phase and L-HL. Finally, the elastic modulus of the two-phase composite sphere composed of the equivalent hydrated cement particles and the porosity of partially leached cement paste is solved using elasticity theory. The effectiveness of the step-by-step analytical solution is verified by comparing with third-party numerical results. Based on the analytical method established in this paper, the effects of hydration degree, volume ratio of calcium hydroxide (CH) to hydrated calcium silicate (C-S-H), and volume ratio of high-density hydrated calcium silicate (C-S-H_a) to low-density hydrated calcium silicate (C-S-H_b) on the elastic modulus of leached cement paste were analyzed. The results show that among the three influencing parameters, the hydration degree has the greatest impact on the elastic modulus of eroded cement paste. This study provides an analytical method for predicting the regression of the elastic modulus of cement paste after calcium leaching, which can provide some reference for the durability design of concrete after calcium leaching.

Key words: cement paste, calcium leaching, elasticity theory, composite sphere model, step-by-step analytical solution

中图分类号:

TU528

齐丰妍, 张坚, 宋文炳, 王海龙, 高云. 溶蚀水泥浆弹性模量预测的分步解析法[J]. 硅酸盐通报, 2024, 43(8): 2758-2767.

QI Fengyan, ZHANG Jian, SONG Wenbing, WANG Hailong, GAO Yun. A Step-by-Step Analytical Solution for Predicting Elastic Modulus of Leached Cement Paste[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2024, 43(8): 2758-2767.

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