摘要
为研究粉煤灰的硅酸盐水泥浆体的电阻率、化学收缩及自收缩的变化规律,定量描述水泥基材水化过程中自收缩和未充水毛细孔体积在化学收缩中所占的比例变化,测定了不同水胶比和粉煤灰掺量的早龄期水泥基浆体的电阻率、化学收缩和自收缩。结果表明:水泥基浆体在硬化减速期的电阻率随时间对数的曲线斜率K和浆体3d抗压强度成线性关系,并进一步论证了K值对水泥浆体结构密实速度的物理意义及其推测强度的应用价值;浆体的化学收缩和自收缩分别随水胶比升高或粉煤灰掺量增大而降低。浆体在24h后的单位体积化学收缩和30h后的自收缩随电阻率的发展均表现出线性关系。定量地提出了终凝后自收缩变化量与终凝后线性化学收缩变化量的比例参数γ的概念,较小的γ值表明:与未充水毛细孔相比,自收缩的比例很小;同一样品的比例参数γ表现出随水化时间逐渐减小。
The relationship among the electrical resistivity,chemical shrinkage and autogenous shrinkage is investigated.To quantitatively understand the volume proportions of autogenous shrinkage and volume of empty cavities to chemical shrinkage during the hydration of cementitious materials,the electrical resistivity,chemical shrinkage and autogenous shrinkage are measured for cement pastes with different water to binder ratios and fly ash replacements of cement by weight.A linear equation is established between electrical resistivity and time in logarithmic scale during decelerating period,in which the slope K has a linear relationship with compressive strength at 3d.The chemical shrinkage and autogenous shrinkage of the pastes decrease with the increasing water-binder ratio or fly ash replacement.The proposed proportionγ,defined as the ratio of the autogenous shrinkage change to the linear chemical shrinkage change after final set,decreases with hydration time due to the increasing strength and elastic modulus ofthe paste.Autogenous shrinkage is a quite small part in chemical shrinkage when compared with empty cavities formed in the paste.
出处
《重庆大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2015年第4期45-54,共10页
Journal of Chongqing University
基金
国家自然科学基金资助项目(51178202)~~
关键词
电阻率
化学收缩
自收缩
水泥浆体
粉煤灰
未充水毛细孔
electrical resistivity
chemical shrinkage
autogenous shrinkage
cement paste
fly ash
empty cavities
