Investigation of the Mechanical Properties of Self-Compacting Concrete (SCC) Reinforced with Hybrid Fibres

Abstract

Self-Compacting Concrete is high-performance substance that flows with its own weight, eliminating the need for vibration and enabling easy placement in congested reinforcement zones. While SCC improves workability and surface finish, it often has lower tensile and flexural strength. This study shows the limitations by incorporating hybrid fibers steel fibers for strength and toughness, and polypropylene fibers for ductility and crack control into M30 grade SCC.

The mix was designed using OPC 53 grade cement, crushed sand as a replacement for river sand, 10 mm coarse aggregate, PCE-based superplasticizer (0.6%), and VMA (0.3%), following EFNARC guidelines. Hybrid fibers were added in varying proportions (0–1%). Fresh properties was evaluated by V-funnel, L-box, slump flow. While hard properties of concrete were tested for compressive test at 3, 7, 14, and 21 days. Final mix ratio was Cement: 312.9 kg/m³, Fine Aggregate: 926.5 kg/m³, Coarse Aggregate: 910.299 kg/m³, Water: 192 kg/m³, with a water-cement ratio of 0.43.

Results shows hybrid fibers enhanced strength and durability, with slump flow decreasing slightly as fiber content increased, and L-box ratios ranging from 0.82–0.98, indicating excellent passing ability. Peak mechanical performance was achieved at 0.75% fiber content, with a transition from brittle to ductile failure.

Overall, hybrid fiber-reinforced SCC demonstrated superior workability, strength, and toughness, making it a sustainable and efficient material for modern construction uses such as bridges, high-rise structures, and precast elements.