OPTIMISING CEMENT COMBINATIONS FOR CONCRETE USED IN CARBONATION AND CHLORIDE EXPOSURE CONDITIONS

摘要

The most effective use of concrete largely depends on the selection of its constituent materials (particularly the cement combination), and the design of mixes according to particular performance requirements for particular environmental exposure conditions. In this paper, a method for optimising blended cement combinations for concrete used in different, ie normal (X0), carbonation (XC) and chloride (XD and XS) exposure conditions has been proposed. The blended materials include pulverized-fuel ash (pfa or fly ash), ground granulated blast furnace slag (ggbs) and their combinations. The optimisation models are established based on the experimental work carried out. Optimising results for the given exposure conditions, which are classified by BS 8500, are discussed. For XO and XC exposure conditions, the optimising aims at a maximum utilisation of non-Portland cement materials content and this will enhance the competitiveness of concrete used in sustainable construction development. For XD and XS exposure conditions, related durability requires the maximum chloride resistance, and a multi-criteria optimisation process was proposed.