Study physico-chemical properties of blended cements containing fixed amount of silica fume, blast furnace slag, basalt and limestone, a comparative study

The present study investigates the effect of substitution of Portland cement by 20% of basalt, as natural pozzolana, on the physico-chemical properties of blended cement in comparison to silica fume, granulated blast furnace slag and limestone. For this purpose, a reference sample and four cements containing up to 20% w/w of silica fume, granulated blast furnace slag, basalt and limestone were tested. Bulk density, compressive strength, total porosity and chemically combined water were determined up to 360 days. The hydration products were investigated with FT-IR and DSC. The results showed that basalt has lower pozzolanic activity at early ages than that of silica fume and slag but at later age increases. Whereas the basalt acts as filled materials at early ages and then its reactivity increase due to pozzolanic reaction. It is concluded that basalt has low pozzolanic activity and has a better filling effect on cement hydration with better physico-mechanical properties than other pozzolanic materials.