The feasibility of using steel fiber reinforced concrete in rectangular containers

Steel fiber reinforced concrete (SFRC) was tested to determine the feasibility of its use in the production of rectangular waste containers. Three steel fiber lengths (5/8-inch, 3/4-inch, 1-inch) were tested. It was found that the optimum fiber content was 2% by volume based on the workability of the concrete mixture. Also, it was found that the most effective steel fiber length was the 1-inch steel fiber.

Steel fibers had a widely varying effect on the compressive strength of SFRC. In some cases a decrease in compression strength occurred even with the presence of steel fibers (probably the result of reduced workability). For design purposes, no increase in compressive strength should be considered.

The contribution of steel fibers to the increase in tensile strength (modulus of rupture) varied for the three fiber lengths. A twelve percent increase in tensile strength was established as a reliable choice for all three fiber lengths. This percent increase was applied to ACI 318-89 equation for modulus of rupture as follows: fr = 7.5 x (1.121) x (f_c')^0.5 = 8.4 x (f_c')^0.5

The internal dimensions of three waste containers (#60, #96, #112) were established, and a wall thickness adequate to provide sufficient capacity without reinforcing steel was determined. The three model numbers correspond to the internal volume of each container in cubic feet. The fundamental material strengths of the SFRC were determined through compression and modulus of rupture tests at seven and twenty- eight days. From the test results, calculations were performed based on a container subjected to only the hydrostatic pressure of the waste; thus, a wall thickness of 31/4- inches was established as a suitable value for each container. The conclusion was drawn that, before extensive production of containers made of SFRC could be practically initiated, tests of full-scale containers should be conducted.