Compressive Strength Dependency on the Effect of Temperature Variation on the Percentages of Steel Fiber in Concrete

The aim of this study is to check the effectiveness of steel fiber on the compressive strength of concrete.

Fibers have long been used as building materials to improve the ductility, tensile, compressive, and flexural strengths of concrete. Although fibers have been known as an effective reinforcement material for concrete structures, it is also acknowledged to be a suitable alternative to reinforcement steel bars.

The objective of this research is to investigate some engineering properties, the compressive behavior of steel fiber reinforced concrete (SFRC), and the effect of elevated temperatures of up to 1000°C on concrete.

Various tests which included the slump test, compressive strength test, as well as heating tests were done. The workability (slump) and thermal effects of M20 SFRC were evaluated.

Based on the results obtained, it could be observed that the workability of the M20 concrete reduced with the increase in steel fiber (SF) content from 0% to 1.6% as values obtained were 80mm, 73mm, 67mm, 61mm and 55mm for SF contents of 0%, 0.4%, 0.8%, 1.2%, and 1.6% respectively. These values showed medium workability of the concrete according to ASTM C-143/C-143 M-03. Also, the addition of SF to plain M20 concrete greatly improved the compressive strength (ƒ_c) with the concrete strength at 26.89N/mm2, 30.41N/mm2, 32.85N/mm2, 35.90N/mm2 and 39.66N/mm2 after 28 days of curing for steel fiber contents of 0%, 0.4%, 0.8%, 1.2%, and 1.6% respectively. The f_c after heating the concrete mix to 1,000°C showed improved thermal resistance with 4.2N/mm2, 8.23N/mm2, 11.63N/mm2, 15.60N/mm2 and 17.20N/mm2 for SF contents of 0%, 0.4%, 0.8%, 1.2% and 1.6% respectively.

The incorporation of steel fibers in the concrete mix decreased the workability of SFRC but increased its compressive strength and balling tendencies.