粉煤灰掺量对水泥浆体电阻率与自收缩的影响

Effect of Fly Ash Content on Electrical Resistivity and Autogenous Shrinkage of Cement Paste

研究了粉煤灰掺量为水泥质量的0%,20%和40%时,水胶比(质量比)为0.3的硅酸盐水泥浆体在72h龄期内的电阻率变化规律和168h龄期内的自收缩变化规律.电阻率采用无电极电阻率测定仪进行测试,自收缩采用电子千分表和棱柱体试件进行测试.结果表明:粉煤灰掺量对水泥浆体的电阻率和自收缩具有显著影响.在凝结前,随着粉煤灰掺量的增大,水泥浆体的电阻率也逐渐增大;在硬化后,随着粉煤灰掺量的增大,水泥浆体的电阻率逐渐减小.在相同龄期时,粉煤灰的掺量越大,硬化水泥浆体的自收缩越小.早龄期硬化水泥浆体的电阻率与自收缩正相关.

The changes of electrical resistivity and autogenous shrinkage of Portland cement pastes with water to binder ratio（by mass） of 0.3 and with different contents（by mass） of fly ash from 0% to 20%, 40% were investigated. The electrical resistivity was determined by a non electrode resistivity apparatus. The autogenous shrinkage was determined by digital dial gauge using a prismatic specimen. The results show that fly ash has a great influence on the changes of electrical resistivity and autogenous shrinkage of the cement pastes. The electrical resistivity of the cement paste increases before setting and decreases after hardened with the increase of content of fly ash. At the same age, the autogenous shrinkage of the hardened cement paste decreases with the increase of content of fly ash. There is a positive correlation between the electrical resistivity and autogenous shrinkage for the hardened cement pastes at the early age.