A feasibility of enhancing the impact strength of novel layered two stage fibrous concrete slabs

This study pioneers the concept of a novel layered two stage fibrous concrete (LTSFC) subjected to falling weight collision. The LTSFC is a newly developed concrete, with unique combination of steel fibres and coarse aggregates that are premixed and preplaced in the formwork in three layers followed by a flowable grout injection in each layer to fill the voids. In this study, some LTSFC slabs were proposed to consider the combined effect of layered and two stage concrete containing different type and combinations of steel fibres. Nine slabs were proposed, casted and tested, for which firstly the LTSFC were prepared and reinforced in three layers of 4%, 2% and 4% with three different fibres viz., crimped fibre (CF), hooked end fibre (HF), combined CF and HF and combined long and short CF. Secondly, the slabs were reinforced with 3.3% of same type of steel fibres over the entire cross section. The average amount of fibre used in LTSFC specimen was 3.3% which is similar to the fibre dosage used in the second series, where the fibres are equally spread in entire cross section. The study parameters viz., number of repeated impacts that induce the first crack and failure, impact ductility ratio, crack resistance (service and ultimate) and impact crack resistance ratio were considered herein. The results indicated that LTSFC specimens exhibited significant increase in the number of repeated impacts for the initial crack and failure to occur, high crack resistance, enhanced ductility and impact crack resistance ratio when related with non-fibrous concrete. Hence, the most significant findings of this research should stimulate innovation and new technology to develop the novel LTSFC in future studies.