LABORATORY INVESTIGATION OF CHLORIDE PERMEABILITY FOR HIGH PERFORMANCE CONCRETE CONTAINING FLY-ASH AND SILICA FUME

摘要

This papers reports the results of a laboratory study on the durability of high performance concretes with various combinations of portland cement (Type I), silica fume, and fly ash (Class C) that were tested for strength and chloride permeability. Two permeability tests were conducted to indicate the resistance of concretes to the penetration of chloride ions. The first test was the rapid chloride permeability test adopted by AASHTO T277 and the other test was the ponding test (AASHTO T259). The results showed that the use of supplementary cementing materials in concrete had advantageous effects on strength and chloride ion permeability. Both permeability tests demonstrated that silica fume and fly ash were very influential in reducing the chloride permeability of concrete. However, the use of silica fume in concrete was more efficient than fly ash in decreasing the chloride permeability. Indeed, combination of silica fume and fly ash with Type I cement yielded a higher strength and lower permeability than the reference concrete with Type I cement only.