Improving the Mechanical Properties of Low, Normal and High Strength Concretes

Improvement the mechanical properties (compressive and flexural strength) of low, normal and high strength concrete (LSC, NSC and HSC) was investigated experimentally in this work by used CFRP sheets and steel fibers. The experimental program of this research was consisted of two parts, first part was aimed to evaluate the effect of confinement by CFRP sheets on the compressive strength on the cubes and cylinders, while the second part was investigated the effect of strengthening by CFRP sheets, adding steel fibers and use both on modulus of rupture. Comparison with unconfined specimens, results show that the confinement by CFRP was increased the cube compressive strength about 208, 47 and 27% for LSC, NSC and HSC, respectively, while the increasing in cylinder compressive strength was 216, 64 and 51%. On the other hand, increasing in modulus of rupture for LSC was 373.93, 84.83 and 506.6% for specimens with CFRP, steel fiber and both used of CFRP with steel fibers, respectively. While this increasing for HSC was 575, 128.2 and 725.64% for CFRP, steel fibers and both used of CFRP with steel fibers, respectively. However, for NSC, the percentage of increasing was 455.7, 73 and 605% for the same order.