On Fresh and Hardened Properties of Lightweight Self-Compacting Concrete

The effects of lightweight aggregate type, content, and maximum size, as well as the water-to-binder ratio, on the fresh and hardened characteristics of lightweight self-compacting concrete (LWSCC), were investigated. Fifteen LWSCC mixtures were prepared with varying proportions of LECA and scoria (100-0, 50-50, and 0-100%) and divided into two groups based on water-to-binder ratios and d max values. The slump flow, T50, V-funnel flow time, and L-box were the fresh properties that were investigated, while the measurements of compressive strength, splitting tensile strength, flexural strength, modulus of elasticity, ultrasonic pulse velocity, and drying shrinkage were carried out in the hardened state. The results indicated that higher scoria content generally declined fresh state properties and improved hardened ones. An increase in d max resulted in a reduction in the amount of superplasticizer needed to maintain the slump flow between 70 and 75 cm. The impact of the d max on the mechanical characteristics of LWSCC was negligible. With increasing the d max from 9.5 to 19 mm, the fc merely decreased by 7, 4, and 5% for S100-L0, S50-L50, and S0-L100 mixes, respectively. For ft, fr, and E, the decrease was between 3.2 and 0.6%. The correlation between compressive strength and splitting tensile strength was close to the CEB-FIP proposed relationship for conventional concrete, whereas the relationship between compressive strength and the modulus of elasticity was appropriately estimated using the ACI 318-19 suggested expressions. None of the proposed relations in ACI 209.2R-08 demonstrated adequate accuracy to predict the drying shrinkage of LWSCC at all ages.