Investigation of the mechanical properties of self-compacting concrete containing recycled steel springs; experimental and numerical investigation

Abstract

Improving the performance of concrete on the one hand and preventing harmful effects on the environment, on the other hand, has caused that in this paper, the effect of adding the galvanized low carbon steel springs with different diameters, pitches and mixing percentages on the mechanical properties of the self-compacting concrete (SCC) is investigated. For this purpose, springs with diameters of 8, 12 and 16 mm, wire thickness of 0.8 mm, and two, four and six pitches in percentages of 0.2 and 0.4 were added to the SCC. Then, the compressive, tensile and flexural strength tests were performed on the specimens. The results indicated that the use of a 12 mm-diameter spring increased the compressive, tensile and flexural strengths by 29, 52 and 36%, respectively, but surprisingly, the inclusion of a 16 mm-diameter spring did not affect the mechanical properties. Moreover, it was found that the diameter of the springs is the most effective parameter on the concrete strength and the number of spring pitches cannot solely cause an increase or decrease in the strength. After performing the experimental tests, the data was collected to predict the mechanical properties of the SCC using Gene Expression Programming (GEP). Then, the proposed equations were validated. The numerical results indicated that the relative errors of the compressive, tensile, and flexural strength models were less than 10%, which proved the high capability of the Genetic Algorithm (GA).