Abstract
Two-stage concrete (TSC) is characterized by its exceptional placement technique, whereby aggregates are first pre-placed in the formwork then injected with a flowable grout. The quality of TSC grout is a controlling factor of the mechanical strength and durability of TSC. Therefore, this study investigates the properties of grout mixtures incorporating two types of fine aggregate including natural sea sand and crushed fine aggregate. The grout mixtures proportions were prepared at a water-to-cement ratio (w/c) of 0.45. Three fine aggregate-to-cement ratios (fa/c) of 0.5, 1.0 and 1.5 were tested. Results indicate that grout mixtures made with natural sand exhibited higher flowability and lower bleeding resistance than those made with crushed fine aggregate. Moreover, increasing the fine aggregate content reduced the grout flowability, while it improved the bleeding resistance and compressive strength. It was concluded that grout mixture made with crushed fine aggregate, (fa/c) = 1.0, and 0.8% high-range water-reducing admixture (HRWRA) was the best for successful TSC grout since it exhibited acceptable flowability, excellent bleeding resistance and high compressive strength. arabic 14 English 79