Experimental investigation on permeability indices and strength of modified pervious concrete with recycled concrete aggregate

Abstract

Pervious concrete is considered as a type of lightweight porous concrete with no fine or with small percentage of fine aggregate. There are many advantages of this form of concrete like lower density, thermal conductivity, lower drying shrinkage and high permeability. The properties of pervious concrete with different levels of recycled concrete aggregate were presented in this research. The considered percentages of recycled aggregate replacement were 50% and 100% by weight of natural coarse aggregate. The effect of aggregate size was studied. The considered aggregate sizes were 9.5 mm and 19 mm. In addition, the effect of using either crumb or fiber rubber, polypropylene fiber, silica fume and styrene butadiene latex were investigated. The properties of pervious concrete were investigated through permeability indices (water permeability, density, voids ratio) and strength indices (compressive, flexural, splitting tensile strengths in addition to pervious concrete degradation). From the test results, the use of recycled aggregate, rubber fiber and crumb rubber slightly affected the permeability indices and negatively affected the strength indices. Based on the splitting tensile strength, the use of 50% and 100% recycled aggregate did not satisfy the typical limits of splitting tensile strength. The use of polypropylene fibers had insignificant effect on the permeability indices and compressive strength but the use of polypropylene fibers enhanced the tensile strength and degradation of pervious concrete. Also, the addition of silica fume and styrene butadiene latex increased density and enhanced the strength indices of pervious concrete. Finally, general relations between studied variables were constructed.