Mechanical and Microstructural Analysis of High-Performance Concrete Incorporated with Hybrid Fibres and Graphene Oxide

Abstract

High-Performance Concrete (HPC) is an exceptional concrete with remarkable performance mostly in all aspects and has a compressive strength more than 60 MPa. This paper investigates the characteristics of concrete by various mechanical tests like compressive, split tensile and flexural strength with the reinforcement of different types of fibres and incorporation of graphene oxide. The microstructural analysis was also done to study the effects of different materials on the concrete. The usage of various types of fibres, Graphene oxide, mineral admixtures, preparation techniques and the utilization of materials in hybrid combinations are being investigated. Denser microstructure, lesser porosity and a homogeneous mixing are the basic requirements of the HPC design. Due to the requirement for a huge quantity of cement in HPC which is responsible for CO₂ emission, abrasion and excessive heat of hydration resulting in cracks, Supplementary cementitious constituents like fly ash and silica fume were used, which also reduces the cost of construction. The nanomaterials react with calcium hydroxide and creates increased C–S–H gels, also aids in attaining a denser microstructure for HPC by filling the voids and pores, thereby providing sites for the nucleation and formation of C–S–H gel. It also helps in reducing the development of nano cracks, while the fibres in concrete helps in the energy dissipation effect during loading conditions and also produces a bridging effect for micro and macro cracks. The compressive, split tensile and flexural strength was observed to be improved up to 30.65%, 91.2% and 89.58% with the reinforcement by the hybrid combination of fibres and nanomaterials. The microstructural analysis on the concrete showed petal like crystals and a denser microstructure, with the usage of graphene oxide. Higher C–S–H and calcium hydroxide crystals formation was also noticed due to the usage of mineral admixtures and graphene oxide. The bridging effect of fibres hold firm in concrete matrix were also seen on the microstructural analysis. Based on the investigations, it has been found that the hybrid usage of the medium hooked end steel fibres, micro basalt fibres and Graphene oxide aides in improving several properties of the HPC.