Experimental investigation on splitting-tension failures of basalt fiber-reinforced lightweight aggregate concrete: Effects of strain rate and structure size

The incorporation of basalt fibres in lightweight aggregate concrete (LAC) is a potentially effective approach to ameliorate failure strength and ductility, which has been extensively applied in concrete structures. This paper investigates the comprehensive effects of strain-rate (ranging from 10-5 to 10-2s-1) and structure size (ranging from 70 to 300 mm) on splittingtension fracture failures of LAC and basalt fibre-reinforced lightweight aggregate concrete (BFRLAC) via a systematic experiment, in terms of failure modes, deformation curves, peak fracture strengths and microstructure mechanisms. Results indicated that the incorporation of basalt fibres with 0.30% volume fraction in LAC enhanced the splitting-tension strength by 27.3-38.0% at quasi-static strain-rate while it increased to 42.3-53.4% at low strain-rate rising to 10-2s-1, which can be attributed to the change of dominated action mode of basalt fibres in bridging and toughening effect and the superior tensile properties of basalt fibres being made the best use. Both LAC and BFRLAC with larger structure sizes performed higher dynamic increase factors (DIFs), showing a stronger strain-rate effect. LAC and BFRLAC performed a dropping trend in splitting-tension strength with the growing structure size but the drop was reduced as strainrate rose. The incorporation of basalt fibres could reduce the sensitivity of splitting-tension strength to structure size, which caused 13.3% reduction in size effect at quasi-static strain-rate while up to 51.7% reduction at strain-rate rising to 10-2s-1. The DIF equations captured through regressive analysis on test results could reasonably describe the strain-rate effect of LAC and BFRLAC considering the influence of structure size and offer a valuable guidance for optimal structure designs and simulation calculations.