水泥砂浆抗压强度与其饱水孔结构特征关系模型  

Relationships Between Compressive Strength of Cement Mortars and Pore Structure Characteristics at Water-Saturation

作　　者：梁华明 乔晶 卢艺菲 王捷 周春圣[1] LIANG Huaming;QIAO Jing;LU Yifei;WANG Jie;ZHOU Chunsheng(School of Civil Engineering,Harbin Institute of Technology,Harbin 150090,China;Cultural Heritage Rehabilitation Institute of China Railway Academy,Chengdu 610036,China)

机构地区：[1]哈尔滨工业大学土木工程学院,哈尔滨150090 [2]中铁科研院文化遗产保护研究院,成都610036

出　　处：《硅酸盐学报》2025年第2期304-312,共9页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(52078172);中国中铁股份有限公司重大课题:近现代特色民族工业遗产保护与活化利用研究(科研院2023-重大-02)。

摘　　要：水泥基材料孔结构对其抗压性能具有决定性影响。为准确描述水泥基材料抗压强度与孔结构的重要关联,利用低场磁共振弛豫技术,对掺引气剂的饱和水泥砂浆进行原状、无损测试,结合抗压强度测量结果,验证并改进抗压强度与孔结构特征间的关系模型。结果表明:低场磁共振技术能准确获取饱和砂浆的孔结构特征,以总孔隙率或分级孔隙率为变量的经验模型拟合效果一般,模型拟合所得经验参数不够稳定,模型的适用性差。基于孔径分布曲线,假设不同孔隙对抗压强度的影响权重与其对数孔径线性相关,所得改进经验模型形式简洁、拟合精度显著提高且能准确反映试件组内差异。此外,基于Griffith断裂理论,以总孔隙率及对数平均半径为自变量的理论模型表达式复杂且预测精度不高。若将半径大于10 nm的孔隙视为缺陷,其影响采用Griffith断裂理论解释;将半径小于10nm的孔隙视作凝胶内部孔隙,它对基体强度的影响近似采用Powers提出的模型描述,所得修正Griffith断裂理论模型的预测精度极高且稳定性、可解释性强,能准确反映孔结构细微区别导致抗压强度差异。引气剂的掺入主要大幅增加半径10 nm以上的毛细孔隙,但同时也会小幅减少半径10 nm以下的基体孔隙,低场磁共振技术能获取水泥砂浆全尺度孔隙结构,进而协助解析孔结构特征与抗压强度的根本关联。Introduction The pore structure of cement-based materials significantly influences their compressive strength.Studies have shown that the nanoscale pore structure significantly changes with variations in water content.Traditional pore measurement methods like mercury intrusion porosimetry and gas adsorption require the drying of specimens,potentially altering or even destroying the pore structure.The accuracy and representativeness of the compressive strength-pore structure relationship model established on this basis are therefore questionable.To accurately describe the important correlation between compressive strength and pore structure of cement-based materials,low-field magnetic resonance relaxation technique is utilized to carry out in-situ,nondestructive testing of saturated cement mortar doped with air-entraining agent.This is then combined with compressive strength measurement results to validate and refine the model describing the relationship between compressive strength and pore structure characteristics.Methods(1)Specimen preparation To avoid the ambiguous effects of ferromagnetic substances when using by low-field nuclear magnetic resonance(LF-NMR)technique,white Portland cement with low Fe_(2)O_(3)content was used to prepare cement mortars with water-to-cement ratio of 0.4.Cement to sand ratio is 1:2.And air-entraining agents(SJ-2 type)were incorporated.Chemical composition of white cement were 0.50%Fe_(2)O_(3),64.60%CaO,21.71%SiO_(2),4.60%Al_(2)O_(3),2.80%SO_(3),2.43%MgO,0.48%R_(2)O.The mass ratio of air-entraining agents to cement was 0%,0.05%,0.10%,and 0.15%.Considering different mass ratios,they are named as WP-BLK,WP-SJ05,WP-WP-SJ10,and WP-SJ15,respectively.According to the designed proportions,the white cement,sand,air-entraining agents and water were mixed and casted into prisms of size 20 mm×20 mm×50 mm.After demounting at 24 h,they were all cured in saturated lime water at(20±2)℃for 180 d.After reaching the specified age,ten specimens were taken from each group of mortar and put into

关 键 词：孔结构 抗压强度 水泥砂浆 引气 低场磁共振技术 

分 类 号：TQ177.62[化学工程—硅酸盐工业]