Durability index performance of high strength concretes made based on different standard portland cements
Advances in Materials Science and Engineering
School of Civil and Environmental Engineering, University of the Witwatersrand, 1 Jan Smuts Ave, Private Bag 3, WITS 2050, Johannesburg, South Africa; Ready-Mix, Lafarge Industries SA (Pty) Ltd., 35 Westfield Road, Longmeadow Business Estate Ext. 11, Gallo Manor 2052, Johannesburg, South Africa
A consortium of three durability index test methods consisting of oxygen permeability, sorptivity and chloride conductivity were used to evaluate the potential influence of four (4) common SANS 10197 cements on strength and durability of concrete. Twenty four (24) concrete mixtures of water-cement ratios (w/c's) = 0.4, 0.5, 0.65 were cast using the cement types CEM I 42.5N, CEM II/A-M (V-L) 42.5N, CEM IV/B 32.5R and CEM II/A-V 52.5N. The concretes investigated fall in the range of normal strength, medium strength and high strength concretes. It was found that the marked differences in oxygen permeability and sorptivity results observed at normal and medium strengths tended to vanish at high concrete strengths. Also, the durability effects attributed to use of different cement types appear to diminish at high strengths. Cements of low strength and/or that contained no extenders (CEM 32.5R, CEM I 42.5N) showed greater sensitivity to sorptivity, relative to other cement types. Results also show that while concrete resistance to chlorides generally improves with increase in strength, adequately high chloride resistance may not be achieved based on high strength alone, and appropriate incorporation of extenders may be necessary. Copyright © 2012 Stephen O. Ekolu and Sheena Murugan.