CHARACTERIZING POROUS CONCRETE MIXTURES FOR RIGID PAVEMENT

In highway engineering, the high porosity of Porous Concrete (PC) facilitates additional functions like noise reduction and urban ambient temperature minimizing, further, to hydroplaning control. The internal composited structure of PC plays the vital role in its mechanical behavior. However, increasing the concrete mixture's porosity can adversely affect the mixture's mechanical properties such as compressive and flexural strength, elasticity, and creep strains. This paper aims to demonstrate an experimental attempt to characterize the mechanical properties of porous concrete pavement (PCP) using local limestone aggregate. The attempt suggested a multistage process to optimize the best mixtures through five stages using different variables, namely: nominal maximum aggregate size (NMAS), w/c ratio, aggregate/paste ratio, superplasticizer dosage, and reactive powder dosage. Firstly, sample preparation was included paste preparation by mixing 75% of the specified mixing water (with SP if applicable) with OPC and SF (if applicable). In comparison, the remain 25% was used to wet the aggregate before continuing mixing. The prepared samples' mechanical and volumetric properties were determined to achieve this optimization process through compressive strength, flexural strength, porosity, coefficient of permeability, and density. The experimental results illustrated a wide range of variation in volumetric and mechanical properties of the produced mixes according to selected variables. The optimization is very significant to gain a PC mixture with an accepted property. Traditional PC mixture comparatively exhibited compressive strength of less than 15 MPa, and flexural strength of less than 3 MPa, while high performance PC mixture exhibited over 30 MPa compressive strength, 5 MPa flexural strength, 1.16 mm/s coefficient of permeability (for the mixture associated with 12.5 NMAS, 80% agg/paste ratio, 0.27 w/b, 0.7% (of binder weight) plasticizer, and 30% (of binder weight) silica fume). However, local limestone aggregate can offer PC mixture suitable for highway pavement when aggregate/cement, additives, and admixture are adequately optimized.