The effects of fine aggregates on the workability and compressive strength of high-strength fine-grained concrete

Concrete is the most commonly used construction material in Vietnam and worldwide for building projects. With the development of the socio-economic sector, infrastructure projects and high-rise buildings are being constructed on an increasingly larger scale, making the demand for manufacturing and utilizing concrete materials with high compressive strength more urgent. This study aims to investigate the feasibility of producing high-strength fine-grained concrete (HSFGC) with a compressive strength of over 100 MPa using locally available materials in Vietnam. The mixtures were designated based on the composition of ultra-high performance concretes (UHPCs), which contain no coarse aggregates. River sand, silica sands, crushed quartz sand, and ceramic powder were used as fine aggregates, while PCB 40 But Son and silica fume SF90 were used as binders in the matrix compositions. The water-to-cement (W/C) ratios used varied from 0.2 to 0.26, combined with a superplasticizer-based polycarboxylate to ensure the flowability of the HSCs. The test results indicated that silica sand produced the highest compressive strength of HSFGCs in comparison with river sand and crushed quartz sand. As the W/C decreased from 0.26 to 0.2, the workability of HSFGCs (flow value) decreased from 26 to 23 cm, but the compressive strength of HSFGC with silica sand increased from 70.4 to 101.9 MPa. HSFGCs with silica sand produced a compressive strength of 101 MPa, while HSFGCs with a combination of silica sand and 10%  ceramic powder can reach a compressive strength of up to 108.1 MPa, making it a promising mix for developing UHPC with economic advantages.