A study on fresh, mechanical, and thermal properties of limestone calcined clay cement (LC3) blended with cementitious materials

In light of environmental concerns about cement manufacture, limestone and thermally activated kaolinitic clays are being explored as supplementary cementitious materials with the potential to reduce CO2 emissions and energy usage. The use of calcined clay and limestone for clinker replacement to create a tertiary blend called limestone calcined clay cement (LC3) is one of the most promising emerging technologies for meeting environmental requirements. This paper reports on the evaluation of the fresh-state and hardened properties of cementitious pastes and self-compacting concretes (SCC) prepared using the concrete equivalent mortar method made with LC3 systems containing 30%, 35%, and 40% metakaolin (LC-30MK, LC-35MK, and LC-40MK) in comparison with ordinary Portland cement (OPC). Paste and concrete equivalent mortar specimens were prepared to investigate water demand, setting time, and workability (mini-slump flow test). Also, the compressive strength and drying shrinkage after 7 and 28 days, as well as thermal conductivity after one year of curing, were examined. The obtained results showed that the incorporation of metakaolin resulted in increased water demand to reach normal consistency. The setting time of LC3 mixtures also increased, while the same workability behavior was observed for all mixtures. LC-30MK can provide compressive strength that is comparable to OPC, especially after the first few days of curing. However, the compressive strengths of LC-35MK and LC-40MK are lower than those of OPC. Nevertheless, they demonstrate noteworthy strength characteristics. All LC3 mixtures exhibited relatively low drying shrinkage and reduced thermal conductivity compared to the OPC mixture.