Study on Strength, Permeability and Micro-structure of Pervious Concrete Blended with Metakaolin

Pervious concrete is a developing construction material used for sustainable solutions which helps restore the groundwater level based on its draining ability. The existing research studies address the strength and permeability of pervious-concrete materials and only limited data is available on the microstructural characteristics of pervious concrete. In this study, a characteristic analysis was carried out at micro-and macrolevels to identify the behaviour of pervious concrete using three aggregate gradations. To attain the wide pore network in pervious concrete, fine aggregates were not added in mixes and metakaolin was added at 5% intervals up to 20% of cement. At the macro-level, strength, porosity and permeability were tested and at the micro-level, XRD, FTIR, SEM and EDAX analyses were used for pervious-concrete mixes with metakaolin. The maximum strength of pervious-concrete was achieved in a 4.75-9.5 mm size aggregate mix at 10% addition of metakaolin with cement. Micro-structural studies revealed that the addition of metakaolin significantly reduces anhydrous calcium hydroxide. A significant draining performance of more than 1 cm/s was attained in most of the pervious-concrete mixes due to high porosity and permeability. Hence, pervious concrete is considered as a sustainable alternative material that can address environmental problems. KEYWORDS: Pervious concrete, Porosity, Permeability, Metakaolin, Micro-structure.