The Importance of High Range Water-Reducers in Concrete Quality

This paper is based on a research project, which has covered the importance of high range water-reducers (HRWR) on properties and consequently on quality of concrete. More precisely deals with the influence of six HRWR of an amount of twelve which were tested. They have been prepared concrete mixes with constant the type and the cement content. Two types of aggregate were used, namely crushed and natural and three (3) admixture dosages (1.0, 1.5 and 2% of cement weight). All mixes were compared with a control mix. The tests have covered the compressive strength (in 3, 7 and 28 days) and the workability tested by slump. The main conclusions are: the higher admixture dosage causes higher compressive strength. The workability also increases. Mixes with crushed aggregates showed higher compressive strength and higher decrease of w/c ratio.