Utilization of limestone powder to improve the properties of self-compacting concrete incorporating high volumes of untreated rice husk ash as fine aggregate

Self-compacting concrete (SCC) is a relatively recent development in the construction industry. It flows under its own weight while remaining homogeneous in composition. We examined the feasibility of using limestone powder (LS) as a modifying agent in self-compacting concrete in which a portion of the fine aggregate was replaced with untreated rice husk ash (RHA). The mixtures were designed to produce a controlled slump flow. The Portland cement content was 550 kg/m3 for all of the mixtures. The fine aggregate was replaced with up to 100% RHA and LS by volume. The T50 slump flow, J-ring flow, blocking assessment, V-funnel, air density, and compressive strength of the SCC mixtures were tested. The fresh properties of the RHA-containing mixtures were improved in mixtures containing less than 60 vol.% RHA. SCCs containing LS exhibited superior hardened properties, and the fresh and hardened properties of SCCs made using RHA were substantially improved when combined with LS. Limestone powder has the potential to improve self-compacting concrete mixtures in which untreated RHA is used as a partial fine aggregate replacement.