Mechanical properties of pozzolan and waste tire aggregate contained steel fiber reinforced concrete

In this study the effect of using pozzolan and waste tire aggregate on steel fiber reinforced concrete (SFRC) properties was investigated. For this purpose, samples with different steel fiber and waste tire ratios were produced in the C30 class. CEM I 42.5 R class Portland cement was used in the mixture and fly ash used as pozzolan. Fly ash was used as a substitute at the rate of 15 % (67.5 kg/m³) of cement weight in the mixture. The water/cement ratio was adjusted to be 0.48 in the control sample mixture and 0.40 in the fibrous sample mixtures using plasticizers. Super plasticizer used as 1,5 % volume of mixture. 35 mm length 0,75 mm diameter galvanized, glued steel fibers were used in the ratio as 50 kg/m³ and 30 kg/m³. Natural aggregates with a diameter of 0-5 mm, 5-12 mm and 12-22 mm were used at the rates of 45 %, 30 % and 25 % respectively. As a substitute for fine aggregate, ground waste tire granules added to fresh concrete mixtures at the rates of 10 % and 15 %. The prepared mixtures were placed in the molds after fresh concrete experiments. Concrete samples taken from the molds after 24 hours were kept in curing tanks in the laboratory for 28 days, then in the open air for 90 days. The produced samples were subjected to Ultrasonic pulse velocity (UPV), split tensile strength, diagonal-cube splitting, three point bending beam, compressive strength, capillary water absorption, freeze/thaw resistance and abrasion resistance tests. For these tests, 30 beams of 100x100x500 mm dimensions and 135 cubes of 100x100x100 mm dimensions were produced. As a result of the experiments, it was understood that almost all of the steel fiber concretes had higher strength compared to the fiber-free control sample. In addition, when steel fiber concretes are compared among themselves, K1 concrete samples containing 10 % waste rubber (50 kg steel fiber) and K3 concrete samples containing 10 % waste rubber (30 kg steel fiber) have higher strength than other concretes. All fibrous samples subjected to 150 and 300 cycle freeze-thaw effect were affected approximately 50 % less than the control sample. When compared with each other, it was understood that concrete samples containing 50 kg steel fiber and 10 % ground waste rubber were more resistant to 300 cycle freeze-thaw effect. When all test results are evaluated collectively, it has been determined that K1 concrete containing 50 kg/m³ steel fiber and 10 % waste tire aggregate is the mixture with the most ideal proportions.