Effect of the key mixture parameters on tortuosity and permeability of concrete

Abstract

The primary aim of this paper is to study the effect of key mix parameters on tortuosity and permeability of concrete's pore system, the two important material properties related to concrete durability. The measurement of tortuosity requires determination of porosity and pore size of concrete. Eighteen different concrete mixes were prepared by varying the levels of the key mix parameters, namely water/cement ratio, cement content and coarse/fine aggregate ratio, and then tested to determine porosity, pore size, tortuosity, and permeability. The experimental data were used to study the effect of the key mix parameters on porosity, tortuosity and permeability of concrete. While all the selected parameters of mix design have some influence on tortuosity of the pore system and permeability, the most dominant one is the water/ cement ratio, which can be rated as the single most significant parameter. Test data also show that permeability decreases with increasing tortuosity, but the decrease is marginal with tortuosity of the pore system exceeding a value of 150. Copyright © 2012 Japan Concrete Institute.