OPTIMIZING MIXTURE OF SELF-COMPACTING CONCRETE FOR CONSTRUCTING A SPILLWAY SURFACE STRUCTURE

Abstract

A spillway apron is a popular hydraulic work with congested reinforcement and complex shapes. Self-compacting concrete (SCC) with excellent workability can meet the technical requirements for the work. This study focuses on determining the SCC optimal mix for efficient use of local coarse aggregates and 100% crushed sand to construct a spillway surface structure. For the purpose, research steps were carried out as follows: (1) optimize mix ratio of coarse aggregates; (2) determine the saturated content of superplasticizer, (3) design SCC preliminary mix; (4) set up an experimental plan; and (5) analyze test data to point out the optimal SCC mix. The investigation of fresh SCC was conducted by slump flow test, slump flow time test, L-box test, and segregation resistance test. Compressive strength, water tightness, and underwater abrasion of hardened SCC were also evaluated. The abrasion tests follow the ASTM C1138-19 method and Yu-Wen Liu's method. The results show that the optimal SCC with slump-flow of 72 cm, the H2/H1 ratio of 0.85, compressive strength at 28 days of 42.5 MPa, abrasion resistance of 0.34 g/cm2; and water tightness of B10 meets specifications of a spillway surface structure. Besides, the abrasion depth measured by Yu-Wen Liu's method of water-borne sand was about four times greater than that of ASTM C1138-19.