Forum Message

Heading: Chlorides Aggregates
I must use marine aggregates (with high chloride content) for concrete production.
There is no possibility for washing the aggregates.
According to your experience is there any admixture (or teqnique)to "neutralize" the chloride effect in concrete?
Has anybody experience from the Middle East countries ?

Best Regards
Spiros Licoudis

spiros licoudis

Water soluble chlorides that cause breaking of protective iron oxide coating on the rebars are harmful. I have not come across any such case reported in the literature. I think it will be worthwhile carrying out long term (say one year)durability studies. Such experience will be quite useful to others also.
Dr J D Bapat

Chlore based admixtures are used to accelerate setting times in concrete block production. So it is not the chlorides that is the problem for the concrete, it is the steel (again).
So look for composite steel bars that are normally too expensive. Investigate the behaviour of stainless steel bars and fiber reenforcement.

Boudewijn Piscaer
Boudewijn Piscaer

There are specified limits of chloride in Concrete, both for RCC and Prestressed Concrete applications, where steel in present in concrete.the range is 0.6 to 0.4 kg/cum of concrete respectively. Hence if chloride levels are within limits, you may use the aggregates.

The limits for Plain Cement Concrete is 3.0 kg/cum of concrete.

The second ways is what Boudewijn has suggested.

Prof. A. K. Tiwari
Ashok Kumar Tiwari

I would like all of you for participating your opinions about the problem with high chlorides aggregates. In the meanwhile I found some time to search in the literature about that.
As Dr Bapat said there are not reported many experiences in the literature.Some papers report the efficiency of high C3A cements or high gypsum cements to bound chlorides.On the other hand there is enough experience on the chloride ingress on existed concrete (and some laboratory tests like RCPT).
There are some differencies on the specifications about the chloride content of aggregates.For example on BS 882:1992 it is reported as limits for chloride content of aggregates (chloride ion content expressed aspercentage by mass of combined aggregate):
Prestressed concrete =0.01
Concrete containing embedded metal=0.03
Concrete containing embedded metal and supplementary cement material PFA or GGBFS=0.05
Other concrete=No limit

Mr Clark you can contact me directly on my e-mail address .
I am really interested to see the efficiency of your admixture.

I don’t have any experience using corrosion inhibitors.
About the use of crystalline admixtures I am keen to have some trials.In the past I had used crystalline admixtures as waterproof concrete and the results were very good.Mr Aldred you can contact me directly on my e-mail address
After all ,I still some questions:
-On plain concrete (with no embedded metal at all) can we use limtless chlorides?That mean we can produce ,for example,paving blocks?
-The rainfall (as an estimation) how much can reduce the chloride content?
-Are there any experience (from the Middle East countries) about the possible use of cement kiln dust byproduct that contains high chloride content?
Best regards and Happy New Year
Spiros Licoudis

spiros licoudis
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