Performance of porous concrete block with different size of coarse aggregate for pavement

Abstract

Nowadays, concrete paving block (CPB) surfacing has become the preferred type of road in urban and residential areas due to its durability and aesthetical value. However, CPB has some disadvantages such as water ponding on the road surface and the generation of noise when vehicle tyre and road surface are in contact. In this study, porous concrete paving blocks (PCPB) has been developed to improve the functional performance of conventional concrete paving block (CPB) in skid resistance, permeability and sound absorption. There were two major phases in developing PCPB in this study. In Phase I, the material properties and characterization were determined through the physical test. Three different sizes of coarse aggregate were used in this study; passing 10 mm retains 5 mm sieve (5 – 10), passing 8 mm retains 5 mm sieve (5 – 8) and passing 10 mm retains 8 mm sieve (8 – 10). Open graded coarse aggregate has been used to allow voids to form inside the PCPB specimens. Phase I was continued with determining the physical, mechanical, microstructure and performance properties of CPB and PCPB. PCPB has been developed from the same CPB design mixture with three different sizes of coarse aggregate with no fine aggregate. All specimens were tested for density, porosity, water absorption, weight loss, compressive, tensile splitting, skid resistance, sound absorption and permeability. In addition, the relationships among these parameters were established. It was found that the single size of coarse aggregate had a slight effect on the strength of the specimens but increased the performance in skid resistance, sound absorption and permeability. However, all the PCPB specimens still achieve the minimum requirements with the porosity more than 15 % and compressive strength above 20 MPa for the individual block. Phase II focused on the functional performance of PCPB in permeability and sound absorption with presence of clogging agent. The specimens have been clogged with 1.0 g/l of road dust for 5 cycles and each cycle was tested. Results gained from the laboratory test show an excellent performance of PCPB (5 – 8) specimens in permeability and sound absorption from virgin stage until after 5 cycles of clogging. The acoustic parameter of specimens showed that PCPB has one peak of the sound absorption coefficient located at low frequency in the range of 500 to 700 Hz and this indicates that PCPB was suitable to be applied as traffic noise mitigation medium especially for low speed traffic. It can be said that PCPB can help in reducing the water ponding, improve driving safety and lowering the traffic noise impact to the surroundings.