EFFECT OF NANO SILICA ON COMPRESSIVE STRENGTH OF HIGH VOLUME FLYASH CONCRETE

Abstract

As the consumption of concrete increases, the world production of cement is continuing and grew to a
significant amount. Portland cement production is a highly energy intensive process, and emits CO2 during calcination
which has a crucial effect on global warming. The production of one tonne of ordinary Portland cement (OPC) releases
approximately one tonne of carbon dioxide to the atmosphere. In this regard it is essential to find environmentally
friendly concrete containing low OPC content but with high performance in strength and durability. For many decades,
the incorporation of flyash as partial replacement of cement in concrete is a common practice and along with that the
use of nano particles has received particular attention in the application of construction materials especially in cement
mortar and concrete.
The basic concept behind using Nano Material which are having large surface area is to improve compressive and
flexural strength at early ages, improved hydration characteristics and reduced porosity and water absorption when
compared with conventional cementitious material.
In this study, effect of Nano Silica (NS) on Compressive strength of High Volume Flyash (HVFA) concrete have been
analysed. The percentage of NS used for replacement were 0%, 1%, 1.5%, 2%, 2.5% by weight of cement and flyash
content were 55% for all the mix. Compressive strength of concrete is tested for M50 & M60 grade of concrete. From the
experimental results it is observed that as days increases compressive strength increases but as percentage of
replacement of NS increases beyond 1.5%, compressive strength decreases but it is higher than the conventional
concrete & normal HVFA concrete.