A Study of the Admixture (Water Reducing-Accelerating) to Develop the Compressive Strength of Concrete Used Crushed Dust as Fine Aggregate

Abstract

This research is related to study the compressive strength of concrete used crushed dust as fine aggregate instead of all amount of sand or some amount of sand and mixing and without mixing with water reducing and accelerating admixture. Mixed ratio 1: 2: 4 (by weight) and water to cement ratio 0.45 without mixing the admixture were found that the mixed concrete at 7 days presented the compressive strength used crushed dust instead of sand 70%, 90% and 100% by weight (sieve analysis) and 100% (not sieve analysis) resulted 275, 260, 241 and 234 ksc respectively and after mixing water reducing and accelerating admixture resulted 292, 287, 276 and 258 ksc respectively and the averaged slump showed at 6.25 cm more than the concrete without admixture about 2 cm. In case of comparing the compressive strength at 28 days between concrete mixed crushed dust and sand the most value of compressive strength showed at the concrete mixed with crushed dust instead of sand 70% = 407 ksc and at normal concrete = 348 ksc and after using the crushed dust instead of all amount of sand the compressive strength appeared nearly same. From this research the crushed dust could be used instead of sand in general concrete structures and could be developed more in the high strength concrete in the future