The effects of low-calcium fly ash (FA), limestone (LS), and dolomitic limestone (DLS) on the properties of cement and mortar has been investigated through a number of tests. Composition of cement hydration products in cement paste and mortar were made with clinker (PC), gypsum (G), FA, LS and DLS. The binders employed were Portland cement (OPC), fly ash-portland cement (FA-OPC), FA-LS-OPC, and FA-DLS-OPC blends with a maximum PC replacement level of 40%, FA level of up to 40%, LS and DLS levels of up to 15%. The hydration rate and products were studied by means of X-ray diffraction (XRD) and Fourier transforms infrared spectroscopy (FTIR). The results showed that the FA, LS and DLS prolong the setting time of the cements. Relative to OPC, in FA-OPC system expansion decreases as the fly ash content of the cement increases. Ternary system, FA-DLS-OPC produces a marked fall ill the expansion of the tested specimens. (C) 2007 Elsevier Ltd. All rights reserved.