Mechanical properties and durability of mortar and concrete containing natural pozzolana and limestone blended cements

摘要

The benefits of limestone filler (LF) and natural pozzolana (NP) as partial replacement of Portland cement arc well established. Economic and environmental advantages by reducing CO_2 emission are well known. However, both supplementary materials have certain shortfalls. LF addition to Portland cement causes an increase of hydration at early ages inducing a high early strength, but it can reduce the later strength due to the dilution effect. On the other hand, NP contributes to hydration after 28 days improving the strength at medium and later ages. Hence, ternary blended cement (OPC-LF-NP) with better performance could be produced. In this paper, mortar prisms in which Portland cement was replaced by up to 20 percent LF and 30 percent NP were tested in flexure and compressive strength at 2, 7, 28 and 90 days. Some samples were tested under sulfate and acid solutions and for chloride ions permeability. Results show that the use of ternary blended cement improves the early age and the long-term compressive and flexural strengths. Durability was also enhanced as better sulfate, acid and chloride ions penetration resistances were proved.