Title:
Effects of High Temperature and Pressure on Strength and
Elasticity of Lignite Fly Ash and Silica Fume Concrete
Author(s):
Sujit Ghosh and Karim W. Nasser
Publication:
Materials Journal
Volume:
93
Issue:
1
Appears on pages(s):
41-50
Keywords:
compressive strength; fly ash; high-strength concretes; high
temperature; modulus of elasticity; pastes; silica fume.
DOI:
10.14359/9795
Date:
1/1/1996
Abstract:
Information is presented on the effects of high temperatures [up to 232 C (450 F)] and high pressures [up to 13.8 MPa (2000 psi)] on the strength and elasticity of concrete (50 to 70 MPa) containing various levels of high-calcium lignite fly ash and a fixed percentage of condensed silica fume. Five different temperatures varying from 21 to 232 C (70 to 450 F) and three different pressures varying from 5.2 to 13.8 MPa (750 to 2000 psi) were used. A gradual deterioration of strength and static modulus of elasticity was observed with a rise in temperature. This phenomenon was observed for all three pressures. Paste microstructure was observed with the aid of a scanning electron microscope. A physico-chemical transformation of the paste took place with the rise in temperature. At high temperatures, chemical transformation of the gel weakened the matrix bonding, which brought about a loss of strength and elasticity of f ly ash and silica fume concrete. The findings of the present study could be useful to the power, nuclear; and oil industries, where fly ash and silica fume are used in concrete exposed to high temper-aturesand high pressures.