chloride attack of concrete

huangyhg

chloride attack of concrete
i previously worked on project were the bridge piers of a highway passing over a major dual carriageway had been attacked by chloride.  the road was subject to sub-zero conditions and a chlorine based de-icier was used to stop the road from freezing.  the sub-grade of the road was slag, a by product of burning coal in power stations with good engineering properties.  but the combination of the slag and the chloride attacked the concrete to the piers rapidly and cause the concrete to become extremely weak.  i think the process or chemical reaction is called thauximite.  but i need conformation on this and also what was the chemical reaction between the slag, chlorine and concrete.  thanks is advance for any suggestions.
hello rich,
it sounds a little like thaumasite sulfate attack.  the samples of it that i have sitting on my desk (i am a very sad person) show bands of white through the concrete and are easily damaged by fingernails.  
i have only had a brief contact with this sort of problem but ws atkins (britain), maintaining agents for the highways agency area 2 (near bristol) have a lot of experience regarding this subject.  there has been several conferences and and papers on this problem but i confess i can't give you any guide here.
richinethiopia,
you might consult