Experimental Research On The Mechanical Properties Of Steel Fiber Fly Ash Concrete At Different Age

The basic mechanical properties of steel fiber reinforced fly ash concrete (SFRFAC) are very important. Previous studies were based on the performance of SFRFAC at the age of 28 days or even longer, while the study on mechanical properties in the hardening process of concrete before 28d was rare. Mastering the developing role of basic mechanical properties of steel fiber reinforced fly ash concrete (SFRFAC), will improve the engineering quality of SFRFAC. In this paper, the law of development of basic mechanical properties of (SFRFAC) with C25 under different ages and different mixing amount of fly ash were studied.When mixing amount of fly ash was 25% and steel fiber volume was 1.2%, It was shown that the relationship between compressive strength before 28d of SFRFAC and ages:fc,cu=-0.809T2+3.7973T+4.8145. Compared with mixing amount of fly ash was 40%, compressive strength at 7d was reduced about 34.7%, when mixing amount of fly ash was 20%, while compressive strength at 28d was reduced about 21.4%.It was shown that the relationship between split-tensile strength before 28d of SFRFAC and ages:f1=-0.0132T2+0.5684T+1.4559.Compared with mixing amount of fly ash was 40%, split-tensile strength at 7d was reduced about 21.8%, when mixing amount of fly ash was 20%, while split-tensile strength at 28d was reduced about 14.9%.It was shown that the relationship between flexural strength before 28d of SFRFAC and age:fm=1.03671n(7)+1.5747. Compared with mixing amount of fly ash was 40%, flexural strength at 7d was reduced about 20.3%, when mixing amount of fly ash was 20%, while flexural strength at 28d was reduced about 13.9%.Research on the basic mechanical properties of steel fiber reinforced fly ash concrete (SFRFAC) before 28d, we found that the optimal mixing amount of fly ash was 20%-30%, this will offer technical support for engineering practice.