Effect of Biopolymer Starch Particle Size on Mechanical Properties of Silica Fume Concrete

Abstract

The study describes the effect of changing the particle size of the biopolymers (starch) on concrete behavior in addition to highlighting the importance of adding starch to concrete because important properties  of the starch such as available, cheap and biodegradable. The effect of starch as a biopolymer on certain properties of silica fume concrete in the hardened state compressive strength, splitting tensile strength, flexural strength, ultrasonic pulse velocity, water absorption and water penetration depth at 7 and 28 days was researched. It has been added to silica fume concrete in an optimum percent 0.5%, but with three different particle size of starch are 197.5 nm, 469.7 nm and 1036.3 nm. The mix proportions were (1:2.8:2.8) (cement: sand: gravel) respectively, for all blends w/c equal 0.47, and constant percentage of ( silica fume of 15%, and superplasticizer of 0.75 percent) by the weight of cement. According to the findings, The optimum particle size was 197.5 nm, which led to an increase in compressive strength 21.6%, 12.5% increase in splitting tensile, and 14.2% increase in flexural strength of concrete, respectively, and a decrease in water absorption and depth of water penetration by 41%, and 45%, compared with the reference mix.