毛细吸水作用对水泥砂浆电阻率的影响研究

Influence of Capillary Water Absorption on Resistivity of Cement Mortar

采用四电极法测定了水泥砂浆电阻率随毛细吸水时间的变化,并分析了水灰比、聚合物乳液、引气剂对其变化的影响.研究表明:随毛细吸水时间的增加,水泥砂浆电阻率先缓慢降低,随后迅速下降,最后保持稳定;毛细吸水可使水泥砂浆电阻率降低70%以上,这可能与吸水后砂浆内部形成的孔隙导电通道有关;增大水灰比和掺入引气剂均可大幅度提高干燥条件下砂浆的电阻率,且对吸水状态下砂浆的电阻率也有一定提高作用,但对吸水后砂浆的电阻率影响不大;6%聚合物乳液掺量(聚合物的固含量占水泥质量的百分数)不仅可提高干燥条件下的砂浆电阻率,也可提高吸水后的砂浆电阻率(提高4倍左右,且保持在360Ω·m以上),原因可能与水灰比、聚合物乳液、引气剂对砂浆毛细孔隙结构的影响有关.

The influence of water-cement ratio,polymer emulsion and air entraining agent on the change of cement mortar resistivity with capillary water absorption time was studied by four-electrode method.The study shows that with the increase of capillary suction time,the resistivity of cement mortar is lowered down,then decreases rapidly,then remains stable;capillary suction can make the resistivity of cement mortar decrease by more than 70%,which may be related to the pore water after the mortar is formed inside the conductive channel;increasing the water-cement ratio and mixing air entraining agent can greatly improve the resistivity of mortar under drying condition,and also have a certain effect on the resistivity of mortar under the condition of water absorption,but have little effect on the resistivity of mortar after water absorption,and the incorporation of 6%polymer emulsion can not only improve the resistivity of dry conditions,but also improve the resistivity of mortar after absorbing water(up to about 4 times,and higher than 360Ω·m),these may be related to the effect of the water-cement ratio,polymer emulsion,air entraining agent on capillary pore structure of mortar.