Evaluation on comprehensive performance of sulfate activated slag self-compacting concrete

Abstract

The current study deals with the production and engineering properties of a self-compacting concrete (SCC) produced with sodium sulfate activated slag binder. A mixture of 5% calcium hydroxide and sodium sulfate varied at different values of 1, 3, 5, 7, and 10% by mass was used as the primary activator of the binder. The fresh properties of the concretes were identified by adapting slump flow, L-Box, air entrained volume, and unit weight. On the other hand, the properties of the hardened concretes were assessed by using the tests on dried density, flexural strength, compressive strength, drying shrinkage, ultrasonic pulse velocity (UPV) and water absorption. Experimental results illustrated that by properly adjusting dosage of superplasticizer (SP) in order to avoid an issue related to lost set, SCC productions were only successfully achieved with sulfate amount limited at 5%. The increment of the sulfate in the range of 1–5% seemed to denser the SCC structure due to the increased unit weight, reduced air entrains, improved strengths, decreased drying shrinkage, increased UPV, and decreased water absorption. Further increase of the sulfate amount in the range of 5–10% induced the hardened concretes with reductions on mechanical strengths, UPV, and water absorption, possible due to the reduced flowability. In this study, 5% of sulfate was considered as the optimum value to produce the concrete with the best quality except the drying shrinkage still decreasing with the sulfate increment.