Physico-chemical and mechanical characteristics and durability of calcium aluminate blended cement.

In this investigation, the hydration characteristics and microstructure of calcium aluminate cement (CAC) contg. different proportions of high slag (HSC) and sulfate resisting cements (SRC) were studied. The blends were made from CAC with the partial replacement of HSC or SRC of 5, 10, 15, 20 and 25 mass%. 10 Mass% of silica fume (SF) was added to all mixes contg. SRC to act as a pozzolanic material to react with the liberated Ca(OH)2 formed during the hydration of the SRC forming addnl. C-S-H and stratlingite (C2ASH8). The prepd. specimens were tested for their compressive strength, hydration characteristics and examd. 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 compns. contg. HSC show its max. 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 1 and 3 days decreased sharply with the percent content of SRC, but, it increases for paste contg. 5 mass% cured for 7 and 28 days. The 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 redn. [on SciFinder(R)]