Evaluation of activity of mineral admixtures at early age and long term in cementitious system

In this study, the pastes with two kinds of fineness of fly ash and GGBS are prepared. The effect of incorporation of fly ash or GGBS with various replacement contents and fineness on pastes has been investigated using non-contact electrical resistivity measurement. Evaluation of mineral admixture behavior in cementitious hydration system at early age has been conducted by analyzing characteristic points on the electrical resistivity development differential curves. The results show that the first peak and the second peak of the differential curves were influenced by the type of the mineral admixtures and their fineness. A resistivity activity index obtained from resistivity measurement is proposed to evaluate activity of mineral admixtures. As a comparison result, the resistivity activity index is consistent with strength index and the resistivity activity index can provide a simple and fast way to evaluate mineral material activity at early ages. The fineness effect of fly ash and GGBS on strength activity index was also analyzed for a long term