Ultra-High-Performance Strain-Hardening Cementitious Composites (UHP-SHCC) is one form of fiber reinforced composites, which has high compressive and tensile strengths along with high strain capacity in tension with strain hardening plateau. Obviously, proper selection of strengthening/retrofitting material plays an important role in restoring the lost capacity of the strengthened/retrofitted member. This paper investigated experimentally the effect of internal reinforcement in the UHP-SHCC specimens on the tensile strength as well as the cracking characteristics. Seven UHP-SHCC specimens with identical dimensions of 500 x 150 x 50 mm were tested under pure axial tension. Different configurations of the internal reinforcement were considered; namely, internal orthogonal mesh of clear spacing of 50 mm in both directions, or smooth bars of 6 mm diameter. For both configurations, different reinforcement ratios were considered. The experiential results showed that the internal mesh configuration enabled the specimen to develop better crack distribution along with higher tensile capacity compared to those of specimens having internal smooth bars configurations. In addition, increasing the internal reinforcement ratio resulted in increase the tensile strength of the UHP-SHCC as well as reduce the average crack spacing.

No 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.

No abstract