Design of a porous concrete mixture for drainage coverslab in pedestrian walkways

A novel design of a drainage coverslab in pedestrian walking areas has been developed as a composite section of reinforced concrete and a porous concrete layer. Porous concrete exhibits a reduction in permeability due to clogging by particulates, which severely limits the functional level of the coverslab. Slabs were tested for sever clogging mechanism in the laboratory. Samples of new coverslabs with various sizes of aggregates were cast using various compaction methods. Strength was tested using 3 point load test and clogging potential of cover slab was determined by infiltration test (ASTM C1701). Infiltration was tested on a series of coverslab samples which were clogged with top soil mixture collected from the field, landscape fine compost and silt clay slurry to simulate worse case clogging in the field. Comparison of surface textures of the porous surface was made based on sand patch test and proposed clay patch test. This paper focuses on discussing the design of porous concrete layer of coverslab, construction methods and practical issues related to application and mitigation techniques.