Sahalarp Homwuttiwong, Narongchai Vivatanachang, and Chai Jaturapitakkul

pp. 269 - 283

Abstract

The purpose of this research was to examine the effect of high volume of fly ash from various sources
on compressive strength and acid resistance of concrete. Fly ashes from 5 sources were collected and classified by an air classifier into 3 groups of different degree of fineness; low, medium, and high fineness. Portland
cement type I was replaced by fly ash at the rate of 50% by weight of cementitious materials (Portland cement
type I and fly ash) to cast concrete cylinders of 10 cm in diameter and 20 cm in height. After fly ash concretes
were cured in water for 28 days, they were tested to determine the compressive strength. In addition, the specimens were immersed in 3% of sulfuric acid solution and the weight losses of concretes were measured
from 3 to 90 days. It was found that the compressive strengths of fly ash concretes were more than 77% of the
control concrete when the high fineness fly ashes were used. Each source of the fly ash had different effect on
the compressive strength as well as on the sulfuric acid resistance of concrete. The compressive strength of fly
ash concrete was improved with the use of high fineness fly ash; however, the sulfuric acid resistance of the
concrete tended to decrease as the fineness of fly ash increased.