早龄期混凝土的电阻率特性和微观形貌研究

Electrical resistivity property and microstructure development of young concrete

采用非接触式电阻率仪对普通混凝土(CO)、掺矿粉混凝土(CS)和掺粉煤灰混凝土(CF)的早龄期电阻率特性进行试验研究,分析矿物掺合料对混凝土中水泥水化的影响,以及不同时间点混凝土中胶凝材料的水化特性,并借助环境扫描电子显微镜(ESEM)对不同龄期的普通混凝土进行微观形貌分析。结果表明:将矿物掺合料以不同百分比取代水泥后,在其他条件不变的情况下,混凝土的初期电阻率(0-M点,加速阶段)随矿物掺合料掺量的增加而增大。普通混凝土的初始电阻率最小,后期(M点-7 d)电阻率会超过掺矿粉混凝土和掺粉煤灰混凝土。3 d龄期内水化产物快速填充混凝土内部的空隙和水化产物的孔隙,而3 d龄期后水化产物进一步填充混凝土内部孔隙。研究结果可为改善混凝土材料的服役性能提供参考。

Electrical resistivity property of ordinary concrete and mineral admixture concrete（ mixed with slag and fly ash） during the early age was studied in a non-contacting electrical resistivity measurement device. Effect of mineral admixture on cement hydration and the development of hydration property with curing time were all analyzed. Take ordinary concrete for example,the microstructure of hydration products were obtained by the ESEM. The experimental results indicate that the concrete initial electrical resistivity（ 0-M stage） increases with the mineral admixture proportion increasing. During the stage of 0-M,the lowest electrical resistivity arose in ordinary concrete,however,it will exceed the corcrete mixed with slag and corcrete mixed with fly ash concrete in the late stage. Within the curing age of 3 d,space in concrete and the porosity in hydration products were filled with newproduced hydration products. After that,the porosity would be further filled by hydration products in concrete,hence,the concrete become more and more dense. Test results can be a reference to improve the concrete service ability.