Study of Mechanical Behavior of Chips Reinforced Concrete

Mechanical behavior of steel fiber reinforced concrete has been studied by the direct tensile test. This fiber concrete is obtained by adding machining chips to the bare concrete. Six fiber contents were adopted (W=0.4%, 0.6%, 0.8%, 1%, 1.2% and 1.5%) for two sand over gravel ratio (S/G = 0.8 and S/G = 1). The results obtained showed that the fibers have substantially improved the stiffness and the strength of concrete and conferred a significant ductility to the material for the fiber volume fractions 0.4%, 0.6% and 0.8% (according to the S/G). The value of residual strength observed after cracking of the concrete matrix was of the same order as for the bare concrete for some of the compositions. Besides the tensile tests, compression tests have been performed. These tests showed that adding a low fiber percentage (W = 0.4%) provides a slight increase of the resistance to compression. Values of W greater than 0.8% lower this resistance. We can conclude that the presence of fibers in concrete is positive, bridging of micro cracks and recovery of the efforts through the developed macro cracks. Unfortunately, the reduction of the compactness has led to a decrease in the tensile strength and the compressive strength. The most advantageous fiber contents for compression are W = 0.4% and W = 0.6% for the two ratios .As for the tensile test, the most advantageous fiber contents are 0.6% and 0.8%. (author)