Air permeability, water penetration and water absorption to specify durability of eco-efficient concrete

Abstract

The durability of eco-efficient, clinker reduced concrete is a key factor of its performance. In the presented study, different durability indicators of a newly developed eco-concrete composition (ECO) are tested versus standard normal concrete as reference (REF). The tested durability indicators are open porosity, water penetration depth, rate of water absorption by capillarity and two different methods of measuring air permeability (PermeaTORR AC device versus Testing bubble counter). The ECO mix and in particular its cementitious matrix is designed by a combined filler concept substituting Portland cement partially by properly selected limestone fillers of different grain sizes. The approach is based on a combination of particle packing optimization techniques and the reduction of water demand for certain flowability of the paste. Cement content is below the limits of traditional standards while w/c-ratio exceed such limits. While the performance of the eco-concrete in terms of workability and strength is at least equivalent to the standard mix, ecological impact indicators as global warming potential and embodied energy are substantially improved. Durability indicators overall show nearly equivalent performance of ECO and REF. In detail, the resulting air permeability coefficient tested with a bubble counter differs significantly from the coefficient tested by PermeaTORR.