EFFECT OF TAPIOCA STRACH ON PROPERTIES OF SELF-COMPACTING CON

Abstract

This project is aimed to be a preliminary study of using tapioca starch as a viscosity modifying agent (VMA) for self-compacting concrete (SCC). The effect of tapioca starch on viscosity of SCCwas investigated from the workability of corresponding mortars. Cement-only mortars with water to cement ratio (w/c) of 0.25 to 0.48, superplasticizer dosage of 1% to 2.5%, starch concentration of 0%, 0.25% and 0.5%, were tested for workability. Mortar mixes that had equivalent workability (flow diameter of 250 mm, and funnel flow time of 5 seconds) for each starch concentration were identified and checked for concrete properties. SCC mixtures were then tested for initial slump flow, slump flow loss, bleeding, setting times, and compressive strength. The results show that all tested concrete mixes provide same initial workability, however the mixes with higher starch concentrations exhibit slower loss. For setting times, mixes with higher starch concentrations demonstrate longer setting times. Compressive strength of starch concretes, which always have higher water to cement ratio (w/c), are lower than that of the concrete without starch as their initial slumps were controlled to be the same in this experiment, however, their strengths are higher or comparable to or higher than the strength range mostly used for conventional concrete.