Contribution of Steel Fiber to the Mechanical Property Improvement of C80 Concrete Produced with a High Amount of Artificial Sand Powder

Due to the high price of river sand, its shortage and unsustainable extraction from the environment, artificial sand (AS) has been promoted as a fine aggregate for producing concrete. However, it has been acknowledged that a high content of limestone powder (LP), up to 15 wt.%, as a by-product in AS coexists and it has an adverse impact on the mechanical properties of concrete. To compensate for the performance loss of C80 concrete with a high LP content to the applications of concrete on a large scale, this study evaluates the contribution of steel fiber content to the performance improvement of concrete by means of a developed statistical method. Experimental results show that when increasing the LP in concrete over 5%, it can influence axial compression, flexural intensity, splitting tension and the modulus of elasticity, in particular, presenting an obvious decrease in axial compressive intensity, splitting tension and modulus of elasticity. Incorporating steel fibers in such concrete prepared with a high amount of artificial sand powder is a way to compensate for its performance loss. Referring to the experimental results and probability theory, the probability density function of the characteristic value of mechanical characteristic of one type of concrete and the difference between the characteristic values of mechanical characteristics of any two concretes were developed to establish a scientific criterion that can be used to compare the sizes of any two characteristic probability values, which is superior to the comparative approach of arithmetic averages in publications. By adopting this method, the high-strength concrete with a high LP and steel fiber content could be applied in engineering practices from the point of view of its mechanical properties. Meanwhile, the study provides an evaluation method for other scientific research on the size comparison of any two stochastic physical variables.

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