Portland-Blended Cement with Reduced CO_2 using Trass Pozzolan

Abstract

This paper reports the use of supplementary cementing materials (SCMs) derived from local resources, for the partial replacement of Portland cement to reduce CO_2 emission during cement production. Replacement of Portland clinkers up to 20 wt.% with SCMs in normal cements reduced CO_2 emission by 0.18 kg CO_2/kg. The compressive strength exceeded the standard specification for Portland cement ASTM C-150. Blended cement samples containing 20% Portland clinker replacement had compressive strengths of 37 MPa after 28 days of curing time. The microstructure evolution of blended cement at a composition of 80:20 was similar to that of the 100% Portland cement, where the structure between days 28 and 56 reached a steady state. Blended cements with compositions of 70:30 and 60:40 still showed progress of CSH plate formation and the lack of massive structure development. It is shown that the use of supplementary cementing materials could be as one of alternative ways to reduce CO_2 emissions during cement production.