Study On Physical Properties Of Hybrid Fibres Reinforced Self Compacting Concrete

Abstract

Self-Compacting Concrete (SCC) can fill congested reinforced sections without external vibration, but brittle behavior, shrinkage cracking, pore formation, and water penetration may limit long-term performance. This study investigated the fresh and physical/durability properties of M40 Hybrid Fiber Reinforced Self-Compacting Concrete (HFRSCC) containing steel and polypropylene fibers at total volume fractions of 0%, 1%, 1.25%, 1.5%, and 1.75%. The mixes used OPC 53 grade cement, fly ash, GGBS, fine and coarse aggregates, superplasticizer, and viscosity-modifying admixture. Fresh performance was evaluated by slump flow/T500, V-funnel, and L-box tests. Hardened properties included density, water absorption, porosity, permeability, and drying shrinkage. Increasing fiber content reduced slump flow from 780 to 640 mm and the L-box ratio from 0.97 to 0.81, while T500 time increased from 2.5 to 6.3 s and V-funnel time from 7.5 to 11.4 s. Density increased from 2364 to 2422 kg/m³. Water absorption decreased from 1.73% to 1.22%; 28-day porosity decreased from 4.44% to 2.94%; 28-day penetration depth decreased from 28 to 12 mm; and 7-day shrinkage strain decreased from 285 to 200 microstrain. On the overall balance adopted in the thesis, the 1.5% hybrid-fiber mix provided the optimum combination of self-compacting behavior and durability-related performance.