Microstructure and composition of hydration products of ordinary Portland cement with ground steel-making slag

The effect of ground steel-making slag on microstructure and composition of hydration products of ordinary Portland cement (OPC) was investigated by mercury intrusion porosimetry (MIP), X-ray diffraction (XRD) and differential thermal analysis (DTA). Results show that ground steel-making slag is a kind of high activity mineral additives and it can raise the longer-age strength of OPC mortar. The total porosity and average pore diameter of OPC paste with ground steel-making slag increase with the increase of the amount of ground steel-making slag replacing OPC at various ages, while after 28 days most pores in OPC paste with ground steel-making slag do not influence the strength because the diameter of those pores is in the rang of 20 to 50 nm. The hydration mechanism of ground steel-making slag is similar to that of OPC but different from that of fly ash and blast furnace slag. The hydration products of ground steel-making slag contain quite a lot of Ca(OH)2 in long age.