Effect of silica fume on the behavior of lightweight reinforced concrete beams made from crushed clay bricks

Abstract

Crushed over-burnt clay bricks (COBCBs) are a promising alternative to the natural gravel aggregate in lightweight concrete (LWC) production because of their high strength-to-weight ratio. Besides, COBCBs are considered a green aggregate as they solve the problem of solid waste disposal. In this paper, a total of fifteen reinforced concrete (RC) beams were constructed and tested up to failure. The experimental beams were classified into five groups. The control beams were cast with normal weight concrete (NWC), while the remaining four groups of beams were prepared from LWC. The test parameters were the concrete type, reinforcement ratio and silica fume (SF) content. The behavior of beams was evaluated in terms of the crack pattern, failure mode, ultimate deflection, and ductility. The experimental results suggested that the weight and strength of the concrete prepared satisfied the requirements of LWC. In addition, the increase in the reinforcement ratio and SF content improved the behavior of the beams. It is noteworthy that the SF addition caused measurable enhancements to the majority of the performance characteristics of LWC beams. Thus, COBCBs were successfully used as coarse aggregates in the production of high-quality LWC. Both ACI 318-19 and CSA-A23.3-19 made acceptable predictions of the cracking moment, ultimate capacity and mid-span deflection.