Cracking behaviour of green lightweight concrete one-way slabs using medium K Basaltic Andesitic pumice and Scoria

This paper investigates experimentally the cracking behaviour of green lightweight concrete one-way slabs where coarse aggregates comprised medium K basaltic andesitic pumice and scoria. Three points bending test was performed on 24 one-way slabs of both lightweight concrete with three compressive strengths and four reinforcement ratios, and 1 one-way slab of normal concrete as control. Responses consisted of crack width, mid-span reinforcement strain and mid-span deflection that were measured for observation purposes. To show the cracking behavior, their low tensile strengths were evaluated by representing their compressive strengths. Load versus crack width and reinforcement strain diagrams are simultaneously used to evaluate their cracking behaviors. Effects of reinforcement ratio, reinforcement stress, type of lightweight concrete and compressive strength to the maximum crack width are also investigated. Similarly, cracking patterns as well as failure modes are observed to show their appropriate performances. The results show that the reinforcement ratio and reinforcement stress are the main factors that affect significantly the cracking behavior and maximum crack width. However, the type of lightweight concrete and compressive strength affect them but less significantly. All one-way slabs exhibited a typical flexural crack, at the first time the reinforcement yields and then the concrete compressive zone crushes.