Effect of Starch Admixtures on Fresh and Hardened Properties of Concrete

Admixtures are used to alter the properties of concrete. Admixtures are substances introduced into a batch of concrete, during or immediately before its mixing. There are numerous benefits available through the use of admixtures such as: improved quality, colouring, greater concrete strength, increased flow for the same water-cement ratio, enhanced frost and sulphate resistance, improved fire resistance, cracking control, acceleration or retardation in setting time, lower density and improved workability. The specific effects of an admixture generally vary with the type of cement, mix proportion and dosage. Starch can be used in concrete as admixture. Starch changes the setting time of concrete. In this particular study, starches used are tapioca and maize. The setting time of concrete is tested using vicat apparatus. The workability of concrete is tested using slump test. The starch is added for testing with different percentages of cement. The setting time and workability of concrete / cement increases with the addition of starch admixtures. Compressive strength, split tensile strength and flexural strength of concrete increases gradually up to an addition of 1.5% of maize and 2% of tapioca. Further increase in the addition of starch admixtures reduces the compressive strength, split tensile strength and flexural strength. The starch admixtures such as maize and tapioca can replace the use of chemical admixtures. It also reduces the additional cost of using chemical admixtuers.