Study of Compressive Strength of Self-compacting Concrete Using Rice Husk Ash and Nano Silica as a Partial Replacement to Cement: A Comparative Study

Abstract

Self-compacting concrete do not require shaking even in packed reinforcement as it gets compressed under its own load. But the biggest question is its durability and economy. When these mineral admixtures are replaced by a part of the Portland cement, then the self-compacting concrete’s cost will decrease proportionally by reducing the heat of hydration. But there is a question on durability as this decreases the alkalinity on concrete and hence increases the risk of corrosion in the reinforcement. This paper shows an experimental investigation on aspects like compressive strength and durability by measuring the cube strength and carbonation depth. The methodology adopted is that cement has been partially replaced with the rice husk without any nano-silica and with 2% of nano-silica by weight of cement with a varying percentage of 0, 5, 10, 15, 20, 25 and 30%. The following conclusions are made such that the best possible dose of superplasticizer and mineral admixture increased the flowing property of concrete and met the requirements of construction industries. The improvements in the flowing and the filling ability of the self-compacting concrete were detected. The compressive strength of concrete without nano-silica enhances after pozzolanic reaction up to 20% replacement with RHA at an age after 60 and 90 days. Addition of nano-silica further improved the compressive strength of concrete on all ages. However, there was a question on the durability as the concrete gets more vulnerable to corrosion because carbonation depth on concrete with nano-silica is more than concrete without nano-silica. From this point of view, the more economical self-compacting concrete design can be developed by incorporating reasonable amounts of rice husk ash and nano-silica provided if proper attention regarding durability aspects is taken into consideration.