Shear Behavior of Green Concrete Beams Reinforced with Basalt FRP Bars and Stirrups.

Abstract

The Reinforced concrete structures when exposed to a harsh environment it will be susceptible to the corrosion of steel reinforcement and shall lead to deterioration process. Consequently, the service lifetime of the structure will be reduced. The climatic conditions are playing an important role in accelerating corrosion; however, this corrosion needs costly repairs, and if these repairs do not start on the early stage then a catastrophic failure will happen to the structure. In order to avoid such failures and costly repairs, fiber reinforced polymer (FRP) could be used as an alternative to the steel reinforcement, which is a non-corrodible material. Moreover, from the design prospective, the FRP cannot be used directly as an alternative to the steel bars and that's because of various differences in the physical and mechanical characteristics. One main difference in the characteristics is that the FRP bars have high tensile strength and lower modulus of elasticity compared to the steel bars. Previous studies have been examined the structure performance with different types of fiber reinforced polymers. This study will mainly focus on the shear behavior of green reinforced concrete beams with Basalt FRP (BFRP) bars and stirrups. A total of 14No. beams with size of 200 x 300 x 2550 mm were examined in the experimental works. Sand coated Basalt FRP (BFRP) bars and stirrups are used for reinforcement of the beams as a flexural and shear reinforcements respectively. The beam will be subjected to four-point loads by the universal testing machine (UTM) till the failure takes over. The parameters investigated in this study are span to depth ratio (i.e. a/d =2.5 and 3.5), reinforcement ratio , stirrups spacing effect (i.e. 250 mm and 350 mm) and stirrups type (Steel and Basalt). The results of the test showed that as the reinforcement ratio increase the stiffness of the beam increases. The study revealed that as the span to depth ratio increases the stiffness of the beam decreased. Results also shows that steel stirrups provide higher stiffness than the BFRP stirrups. In addition to this, it has been determined that green concrete provides high compressive strength but low flexural capacity where increasing the fly ash, affecting the flexural capacity negatively. However, it increases the workability of the concrete. It has been found that the green concrete provides high compressive strength compared to the normal concrete with the same workability properties, which increases the shear resistance by the concrete. Finally, minimizing spacing of the stirrups is not preventing occurrence of the crack, however using minimum spacing helps in decreasing the crack width.