Mechanical performance of waste marble based self compacting concrete reinforced with steel fiber (Part I)

A two-phase testing setup was established to achieve the research's goal. In the initial phase, response surface methodology (RSM) was used for the optimization of marble waste and superplasticizers. In the second phase, five batches of fiber-reinforced concrete are casted with differing proportions of steel fiber (SF) ranging from 0 to 2.0%. Slump flow, slump T50, V-funnel, and L box tests were utilized to evaluate the passing and filling abilities of SCC. Compressive, tensile, flexural, pull-out and impact strength tests were conducted to evaluate the mechanical strength. Furthermore, failure modes and cracking behaviors were also studied. Scan electronic microscopy (SEM) test was used to study the internal structure. Experiments show that RSM can be successfully used for optimization. The filling and passing ability of SCC was declined with the addition of SF. However, it can be observed that up to 1.5% addition of SF falls inside the limit described by guidelines for SCC with good filling and passing ability. Strength properties improved with the addition of SF up to 1.5% addition due to bridging effects. Furthermore, SF does not considerably improve the compressive capacity (only 8.0% improved compressive capacity), but it changes the brittle failure into ductile failure. However, significant enhancement was observed in tensile strength, flexural strength, pull-out strength, and impact energy absorption which is 66%, 86%, 80%, and 75% (28 days) more than from the reference blend respectively. The study concludes that with the optimization of plasticizer and SF through RSM, better performance of SCC can be achieved. However, a higher dose of SF (2.0%) decreased the SCC performance due to the absence of workability. Therefore, the research suggests to used SF up to 1.5% or recommending a higher percentage of plasticizer for a higher dose of SF.