Water Permeability Study of High-Performance Concrete

The results of an experimental investigation on the water permeability of high performance concrete are presented. Several aspects were studied including different components for the concrete as well as the load history for the test specimens. The concrete was made with Brazilian Type CP V ARI cement (ASTM Type III), two different aggregates (limestone and gneiss) and silica fume. The concrete compressive strength was above 50 MPa at 28 days. For the water permeability test, the apparatus developed by Ludirdja et al. at the University of Illinois was employed. Permeability tests were initiated 10 days after casting the concrete. At that time, the test specimens were subjected to different load histories. In series 1, the applied load was equal to 40% of the ultimate compressive strength, while in series 2 this value was increased to 70%. The secant modulus of elasticity and the splitting tensile strength of the concretes at the start of the permeability tests were also evaluated. The test results indicate clearly the effects of the load history on the value of the water permeability coefficient. As the load increases, the value of this coefficient also increases. The results also show that for high-performance concrete produced with Brazilian Type CP V ARI cement, the prescribed compressive strength may be reached in a short period of time, but the long-term water permeability coefficient seems to require a longer time to develop.