Effects of Aggregate Grading and Admixture/Filler on Self-Consolidating Concrete

Abstract

Self-consolidating concrete (SCC) is becoming a popular choice in concrete industry due to ease of placement in congested reinforcements, reduced labor and equipment, nonsegregating character, and smooth surface. Due to its sen- sitivity to aggregate grading, proportions, admixtures, and filler contents and being a relatively new material, more infor- mation are required on the effects of aggregate grading, mineral admixture types, and fillers on fresh and strength proper- ties. In this paper a total of 10 SCC were investigated to compare the effects of aggregate size and distribution, mineral admix- ture, and filler on fresh properties through slump-flow, J-ring, L-box, column segregation, and compressive strength tests. Results show that combined aggregate distribution is critical for selecting proper SCC mixtures. Water/powder ratio and paste volume has more effects on SCC than water-cementitious material ratio. In general SCC properties can be greatly influenced by admixture types and dosage, and filler. Consistent with this trend, a study is undertaken for the development and evaluation of fresh and cracking properties of SCC using locally available crushed limestone and sand as an aggregate, fly ash and slag from local plants, commer- cial admixtures including silica fume and limestone powder. As properties of SCC vary greatly due to aggregate type, gradation; mineral and chemical admixtures types and dos- age, a total of 10 SCC mixtures were prepared using various combinations of aggregates and admixtures. This paper will evaluate and compare the fresh properties and compressive strength of various SCC mixtures developed with different combinations of aggregate, mineral admixtures, and filler. The aggregate gradations will also be compared with the developed combined aggregate gradation optimized for con- crete workability, economy and strength by Shilstone (4) for normal concrete.