READY MIXED CONCRETE CONSTITUENT MATERIALS; PLASTICIZING CHEMICAL ADMIXTURES AND EFFECTS ON FRESH AND HARDENED PROPERTIES

Abstract

The effects of plasticizing admixtures on the properties of fresh and hardened ready mixed concrete were studied. Eightdifferent concrete mixtures were designed by two different polycarboxylate based plasticizing admixtures, CEM III/42,5 Ntype Portland cement, ground granulated blast furnace slag, natural sand, crushed limestone, and water. Flow ability of thefreshly mixed concretes were measured and the compressive strength tests were carried out on 150 mm cubic specimens atthe ages of 7 and 28 days. It was observed that flow values increased when the amount of admixture used in the mixturesincreased. The composition of the admixture affected the flow values of the mixtures significantly. Compressive strength testresults revealed that the increase in amount of slag in the amount of total binding material resulted in lower 7-days strengthvalues. Type of chemical admixtures significantly influenced the 7-days strength values. This was attributed to the differentsecondary effects of different plasticizing chemical admixtures. Type of chemical admixture influenced both 7-days strengthand 28-days strength even the mixtures had equal amounts of ingredients and also equal water/binder ratios. This resultshowed that plasticizing chemical admixtures can affect both early and later age strengths of ready mixed concrete even forequal water/binder ratios.