Self-consolidating concrete incorporating new viscosity modifying admixtures

Abstract

Self-consolidating concrete (SCC) is known for its excellent deformability, high resistance to segregation and use without applying vibration in congested reinforced concrete structures characterized by difficult casting conditions. The use of viscosity modifying admixtures (VMA) has proved very effective in stabilizing the rheology of SCC. Commercial VMAs currently available on the market are costly, which increases the cost of such a concrete. This article presents the suitability of four different types of new polysaccharide-based VMA in the development of SCC. A preliminary investigation was carried out on the rheological properties and setting times of mortar mixes with various types and dosages of VMA to study the influence and suitability of new VMAs. A more detailed study was then carried out on the SCC fresh and hardened properties such as slump flow, segregation, bleeding, flow time, setting time and compressive strength of different mixes with various dosages of an identified new VMA. The performance of various SCC mixtures with the new VMA was compared with a SCC using a commercial VMA designated as “COM” and a SCC mixture with Welan gum. The study on new VMA is encouraging and confirms the production of satisfactory SCC with acceptable fresh and hardened properties comparable with or even better than that made with commercial VMA and Welan gum. The suggested mix with 0.05% of the new Type A VMA satisfies the requirement of fresh and hardened properties of SCC and will require 7% less VMA dosage than that required in the commercial VMA mixture. The SCC with new VMA is also cost-effective.