Impact and static behavior of strain-hardening cementitious composites–strengthened reinforced concrete slabs

Abstract

Impact loading could impair the entire structure or a part of it, thus making the human life at stake. In this study, to improve the impact resistance of reinforced concrete slabs under drop-weight loading, a thin layer of strain-hardening cementitious composites was added at either tension or compression side of the slab. The main parameter of this study was the three contact surface conditions, namely grinding, grinding plus steel dowels, and grinding plus epoxy adhesive, between the substrate slab and the strain-hardening cementitious composites layer. Therefore, 63 reinforced concrete slabs were prepared and tested under the effect of drop-weight falling from three different heights: 1, 1.5, and 2 m. In addition, for comparison purposes, additional seven slabs were tested under central incremental static loading until failure is presented. It was found that the strain-hardening cementitious composites–strengthening layer enhanced the impact and static response of the strengthened slabs when added at either tension or compression side. Besides, to achieve the outermost impact resistance showing ductile performance, it is better to provide a thin layer of the strain-hardening cementitious composites at the tension side of the slab connected to the substrate slab by epoxy resin applied on pre-prepared grinded surface.

Enhancing Performance of Engineering Structures under Dynamic Disasters with ECC–FRP Composites: A Review at Material and Member Levels

“…In recent years, members strengthened with an ECC layer have been extended to the dynamic field to satisfy the requirements of engineering structures in resisting dynamic loadings such as impact or blast. Commonly employed strengthening methods involve applying compressive or tensile strengthening to the top and bottom surfaces of the structure [64][65][66][67][68][69][70][71][72][73][74]. The fibers in the ECC layer not only improve the ductility of the layer but also increase its energy absorption capacity.…”

“…The addition of an ECC layer can significantly enhance the strength, ductility, and deformation capacity of the member, while also mitigating secondary damage caused by impact fragments. When the ECC is applied to the impacted side of the specimen, it can effectively absorb impact energy, reduce the surface damage caused by the impact, and prevent brittle damage by compression on the impacted side [66,67]. On the other hand, when the ECC layer is positioned on the tensile side, it helps reduce the bottom tensile cracks caused by impact load.…”

“…The ECC layer on the tensile side undergoes extensive micro-cracking before reaching failure. With the presence of fiber bridging, it can absorb a large amount of energy, thereby avoiding instantaneous major cracks leading to directly brittle failure of the specimen [64][65][66][67].…”

“…ECC strengthening also shows remarkable effects in improving the impact resistance of RC members subject to impact loading. Mahmoud et al [66,67] demonstrated that RC slabs strengthened with ECC exhibited higher impact resistance compared to unstrengthened slabs. The specimens strengthened on the tensile side in both static and impact conditions showed higher strength and smaller mid-span deflection than those strengthened on the compressive side.…”

Behavior of RC Beams with Circular Openings reinforced with Strain-Hardening Cementitious Composites (SHCC)

“…In recent years, numerous studies have examined the structural performance of SHCC-RC composite components. They figured out how to combine SHCC with a variety of elements to enhance their strength and ductility [19][20][21][22][23][24][25][26][27]. The structural application of SHCC pre-cast forms is still a major issue, despite the fact that several studies have been undertaken on SHCC materials and members.…”