The effect of hybrid basalt fibres on the mechanical and structural characteristics of geopolymer concrete containing geopolymer-coated recycled concrete aggregates

The growth of unavoidable urbanisation and ageing infrastructures lead to the demolition of old concrete buildings, generating massive amounts of concrete waste and environmental concerns. This paper investigated the mechanical, structural, and micro-structural properties of geopolymer concrete containing geopolymer-coated recycled concrete aggregates. Cylinder and prism samples were cast with self-compacted and ambient cured geopolymer concrete (SCGC) containing crushed concrete waste as the aggregates and the hybrid length of 12 mm and 30 mm basalt fibres (BF) with a mass fraction of 2 %. All reinforced prisms were subjected to a three-point bending test until reaching the point of failure. The ultimate load, failure load, crack propagation, post-diagonal cracking, and deformation properties of the 28-day cured concrete were explored for different mix proportions. The experimental findings demonstrated that the inclusion of Basalt fibres in the SCGC with coated RCA played a role in restricting shrinkage cracks, thereby enhancing the properties of the SCGC with coated RCA and improving the splitting tensile strength, ultimate load, failure load, and with higher prisms' deflection at failure and ultimate load. • Recycled concrete aggregates (RCA) were coated with geopolymer slurry, and cured in ambient temperatures for one day. • The hybrid length of 12 mm and 30 mm basalt fibres were incorporated to enhance the properties of self-compacted geopolymer concrete (SCGC). • The rheological, mechanical, and microstructural properties of the mixes containing coated RCA and basalt fibres were studied. • The structural properties of the mixes were studied by conducting three-point bending test on the reinforced prisms.