Submitted by: Bharat Mandal
Supervisor:
Dr. Mohan Prasad Aryal
Abstract
In the past few decades, significant amount of the experimental work has been done to replace the cement with pozzolanic industrial by-products (fly ash, ground granulated blast furnace slag, condensed silica fume, rice husk ash etc.) in different part of the world.
This study gives an overview of the physical and chemical properties of some of the coal ashes and stone dust available in Nepal and deals with the properties of fresh and hardened cement concrete with these mineral admixtures. The properties of fresh concrete investigated include workability, normal consistency, setting time, and autogenous temperature rise and those of the hardened concrete include compressive and flexural strengths, modulus of elasticity, Durability to chloride and sulfate attack, water absorption and pore refinement characteristics, and microscopic study. In addition, the effects of different percentage of coal ash and stone dust on the properties of concrete at different structural levels (paste, mortar & concrete) have also been carried-out.
Data indicate that the replacement of cement by coal ash as mineral admixture in cement concrete in the range of 20% to 30% of cement by weight gives nearly same strength in 14 days and almost 25% more strength in 28 days. In the case of replacement of cement with stone dust by 20%, compressive strength decreases slightly at the age of 28 days. The concrete replaced by 20% coal ash has been found to be more durable against acid and sulfate attack than concrete without ash. Similarly Use of such mineral admixture decreases the heat of hydration.