Development of a Simplified Method of Designing Pervious Concrete Mixes using chip aggregate

Abstract

Pervious concrete can be referred to a sustainable paving material which reduces urban runoff, heat-island effect and improves the ground water quality. Due to the lack of awareness and the unavailability of a simplified design method, the applications are limited in the local context. In this research study, a new method of preparing pervious concrete mixes using commercially available chip aggregate together with coarse aggregate was developed. Five volume based binary combinations were prepared with varying coarse aggregate and chip aggregate proportions. A simple mix design method which is based on the porosity of the pervious concrete was used to determine the required cement paste content. For each aggregate combination, cement paste contents were calculated for four different design porosities. Overall, twenty pervious concrete mixes were prepared and test specimens for compressive strength, bending strength and permeability tests were conducted. Based on the test results, relationships between aggregate combination, compressive strength, permeability, and cement paste content were identified and a simplified graphical method of designing pervious concrete mixes to achieve required strength and permeability characteristics was introduced. Further, the addition of chip aggregate enhanced the strength characteristics while retaining adequate permeability. KEYWORDS: Chip aggregate, Coarse aggregate, Pervious concrete, Cement paste, Mix design.