Cracking behavior of steel fiber reinforced waste sand concrete beams in flexure - Experimental investigation and theoretical analysis

Waste sands resulting from coarse aggregate extraction are becoming an increasingly pressing ecological issue in northern Poland, the Middle East or North Africa. In order to manage the waste sand, a fine-grained composite with the addition of steel fibers has been developed. As steel fibers constitute 1.2% of the composite, it has been called Steel Fiber Reinforced Waste Sand Concrete (SFRWSC). The physico-mechanical and rheological properties of the composite meet the requirements of construction materials and make it more effective than ordinary concrete. In order to prove SFRWSC's usefulness in the production of construction elements, experimental investigations on flexural behavior of full-scale conventionally reinforced concrete beams have been carried out. The test specimens were divided into three series differing as to the conventional reinforcement ratio. It has been demonstrated that SFRWSC can be readily used in the production of bending structural elements as regards cracking limit state. Steel fibers decrease considerably crack spacing and crack width. The analysis also includes cracking moment, maximum crack width - average crack width relation as well as variability of the obtained results. Next, the experimental research results have been compared with the calculation results according to RILEM and Model Code 2010 provisions. It has been proved that crack widths calculated in accordance with the aforementioned international regulations are underestimated in relation to experimental values. The obtained results highlight the necessity to correct these methods before using them for designing elements made from SFRWSC and Steel Fiber Reinforced Concrete (SFRC).