Mechanical properties and microstructural analysis of slag based cementitious binder with calcined dolomite as an activator

Blast furnace slag (BFS) incorporating with natural dolomite calcined at temperature 900 °C for producing the no-cement alkali-activated cementitious binder was investigated. Test results indicate that the hardened paste specimen with 20 wt% dolomite has the highest compressive strength of 30.71 MPa at age of 28 days. The addition of calcined dolomite has an apparent effect on increasing the thermal conductivity of hardened paste specimen at 28 days by about 7.03, 12.79, 22.41, and 28.77% with the added amount of calcined dolomite of 10, 20, 30, and 40 wt% and on the increasing dynamic Young's properties of the specimens with calcined dolomite of 10, 20, 30, and 40 wt% at 28 days by 40.68, 55.07, 61.32, and 70.17% than the pure slag paste. The X-ray diffraction (XRD) indicated the main hydration product of pure slag paste was only the calcium silicate hydrate (C-S-H). However, the hydration product of slag-dolomite paste were the C-S-H, portlandite, quartz, calcite, and magnesium calcite, together with the appearance of quartz in the specimen with the calcined dolomite more than 20 wt%, which is a major factor for the increased compressive strength.