Impact Resistance and Strength Reliability of Novel Two-Stage Fibre-Reinforced Concrete

Two-stage fibre-reinforced concrete (TSFRC) is a novel fibrous concrete that differs from the conventional fibre-reinforced concrete (FRC) in several aspects including its placement technique, implementation, fabrication methodology, and high coarse aggregate content. Consequently, the available data from the open literature on the behaviour of the conventional FRC exposed to falling weight collision may not be applicable to TSFRC. For instance, the impact strength performance of the conventional FRC is well documented; however, for TSFRC this has not been duly examined. For the first time, this study pioneers the concept of impact strength of TSFRC under falling weight collision. For this purpose, short crimped fibres and long hooked end steel fibres at 1.5, 3.0, and 5.0% dosage were used in two-stage concrete (TSC). To this end, seven different mixes were prepared and tested under falling weight collision as per ACI committee 544. In addition, a statistical analysis has been performed to analyse the scattered test results by Weibull distribution. For determining Weibull parameters, 20 probability estimators have been used, and the best estimators are taken for the reliability analysis. Based on the obtained Weibull parameters, the impact strength of TSFRC has been reported in terms of reliability. The results revealed that the ability of using higher fibre dosages allows achieving greater impact resistance properties for novel manufacturing TSFRC. Indeed, the TSC with steel fibre dosages exceeding 5%, can be produced easily thus making this innovative, yet simple to produce concrete, a strong contender in many construction applications. The two-parameter Weibull theory has been found to be adequately suitable for analysing the variations in the number of impacts that induces first crack and failure of all group of TSFRC specimens.