Influence of Hybrid Basalt Fibres’ Length on Fresh and Mechanical Properties of Self-Compacted Ambient-Cured Geopolymer Concrete

Abstract

Recently, short basalt fibres (BFs) have been gaining considerable attention in the building materials industry because of their excellent mechanical properties and lower production cost than their counterparts. Reinforcing geopolymer composites with small volumes of fibres has been proven an efficient technique to enhance concrete’s mechanical properties and durability. However, to date, no study has investigated the effect of basalt fibers’ various lengths and volume content on self-compacted geopolymer concrete’s fresh and mechanical properties (SCGC). SCGC is prepared by mixing fly ash, slag, and micro fly ash as the binder with a solid alkali-activator compound named anhydrous sodium metasilicate (Na₂SiO₃). In the present study, a hybrid length of long and short basalt fibres with different weight contents were investigated to reap the benefits of multi-scale characteristics of a single fibre type. A total of 10 mixtures were developed incorporating a single length and a hybrid mix of long (30) mm and short (12) mm basalt fibres, with a weight of 1%, 1.5% and 2% of the total binder content, respectively. The fresh and mechanical properties of SCGC incorporating a hybrid mix of long and short basalt fibres were compared to plain SCGC and SCGC containing a single fibres length. The results indicate that the hybridization of long and short fibres in SCGC mixture yields better mechanical properties than single-length BF-reinforced SCGC. A hybrid fibre coefficient equation will be validated against the mechanical properties results obtained from the current experimental investigation on SCGC to assess its applicability for different concrete mixes.