Effect of metakaolin content on the properties self-consolidating lightweight concrete

This paper presents the fresh, mechanical and transport properties of expanded shale aggregate self-consolidating lightweight concrete (SCLC) containing metakaolin assessed by means of slump flow, flow time, V-funnel, L-box, compressive, flexural/splitting/bond strength, water absorption, porosity, sorptivity and rapid chloride permeability tests. Metakaolin content based SCLC mixtures were developed by incorporating 0%, 20%, 40% and 60% of as a replacement by weight of fly ash while keeping a constant cement and mineral admixture content of 450 kg/m3 and 150 kg/m3, respectively. These included four mixtures containing 0%, 5%, 10% and 15% metakaolin content as a partial binder replacement. It was observed that expanded shale aggregates SCLC can be produced with the density lower than 2000 kg/m3 which was increased by the addition of metakaolin. Increases in metakaolin content worsened the filling and passing ability of SCLC and by the addition of metakaolin no positive effect on the strength properties on SCLC was monitored. Replacement of 20%, 40% and 60% of metakaolin with fly ash resulted 3%, 8% and 10% decrease in porosity and water absorption with respect to control mixture, respectively. The initial and secondary sorptivity values of SCLC mixtures with metakaolin replacement were equal or lower than the control mixture without metakaolin. Moreover, increases in metakaolin content showed significant improvement in chloride ion penetration resistance of SCLC.

► Develop self-consolidating lightweight concrete with shale aggregate and metakaolin. ► Strength properties including bond are not affected by metakaolin addition. ► Metakaolin reduces porosity, water absorption and filling/passing ability. ► Metakaolin addition improves chloride ion penetration resistance.