Papers by Keyword: Initial Curing Condition

Abstract: The effects of initial high humid air-curing, standard water-curing and sealed-curing on thaumasite form of sulfate attack (TSA) of cement based materials were studied. The erosion products after three years attack in 5% MgSO4 solution were analyzed by means of X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Initial high humid air-curing can delay the TSA of specimens for CaCO3 generated by carbonation and filled in the pores of the specimens, forming a compacted surface and restricting the intrusion of SO42-. In comparison, specimens cured in sealed condition occurred TSA most serious resulting from that large amount of inter-defects in specimens for the lower hydration degree, and SO42- ions could intrude into specimens more easily.

Abstract: In order to study the influences of initial curing conditions on fly ash (FA) cement concrete durability, fly ash cement samples with 30% replacement ratio were fabricated and cured in water at 10°C, 20°C, 30°Cand 40°C for 3d, 7d, 14d and 28d respectively. Hydration degrees of fly ash at early age were measured using the selective dissolve method. Correspondingly the pore structure and morphology of FA-cement mortar and compared cement mortar were studied by using MIP and SEM methods. Then early age compressive strengths of FA-cement concrete and compared normal cement concrete were tested. Experimental results show that initial curing temperatures and ages are important factors to fly ash early age hydration degree, FA-cement system microstructure, morphology and early age compressive strength etc. High curing temperatures and longer curing time can lead higher fly ash hydration degree, and then higher compressive strength of FA-cement concrete, and make the micro-structures of fly ash-cement system denser.