Mechanical strength and corrosion detection of pozzolanic cement

Abstract

Various pozzolanic cement pastes based on ordinary Portland cement (OPC), granulated blast furnace slag (GBFS) and metakaolin (MK) were studied. Mixes were prepared using a water/solid ratio (W/S) of 0.25wt.%. Hydration characteristics of the different hardened cement pastes were investigated via the examination of chemically-combined water content, compressive strength, and X-ray diffraction analysis under normal curing conditions at various time intervals up to 90days. Thermal analysis (DTA/TGA) was carried out for the mix containing 30% Mk and GBFS at 28days. The electrical conductivity was measured during the early stages of hydration for the various cement pastes at 30°C. Moreover, the corrosion potential of reinforced steel embedded in the metakaolin–slag–cement system was studied in comparison to their corresponding ordinary Portland cement, to evaluate the probability of steel corrosion. The results showed that the values of Wn% in these blended pastes are higher than blended pastes with slag or metakaolin only. Also, mix containing 70% OPC, 15% Mk and 15% GBFS has higher compressive strength and corrosion resistance than the net cement paste. The results of thermal analysis indicate that the presence of 30% GBFS and MK consumed the CH formed as a result of the hydration of OPC (pozzolanic reaction).