Hydration characteristics and durability of calcium aluminate cement containing some blended systems

In this investigation, the hydration characteristics and microstructure of calcium aluminate cement (CAC) containing different proportions of high slag (HSC) and sulphate resisting cements (SRC) were studied. The blends were made from CAC with the partial replacement of VISC or SRC of 5, 10, 15, 20 and 25 mass\%. 10 mass\% of silica fume (SF) was added to all mixes containing SRC to act as a pozzolanic material to react with the liberated Ca(OH)(2) formed during the hydration of the SRC forming additional C-S-H and stratlingite (C(2)ASH(8)). The prepared specimens were tested for their compressive strength, hydration characteristics and examined by XRD, DTA, FT-IR spectroscopy and SEM. The effect of HSC added to the CAC on the resistivity against some aggressive media such as 5\% NaCl or 5\% MgSO4 was also investigated. The results of compressive strength of pastes made of mix compositions containing HSC show its maximum at M.20 (20 mass\% HSC). With an increase of HSC content up to 25 mass\%, the strength decreased. On the other hand, the strength values of the pastes cured for I and 3 days decreased sharply with the percent content of SRC, but, it increases for paste containing 5 mass\% cured for 7 and 28 days. ne compressive strength values of specimens immersed in 5 mass\% NaCl or 5 mass\% MgSO4 increases up to M,20 (20 mass\% HSC) at all curing ages up to 120 days. The increase of the BFSC content up to 25 mass\% (M.25) was accompanied by a corresponding strength reduction.