Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Chloride contamination in fine aggregate

[Subject Prev][Subject Next][Thread Prev][Thread Next]

On 4/27/06, Terangue Gillham <tiger(--nospam--at)> wrote:

I deal with concrete suppliers who use dredged sea sand for batching, and I
need to specify a standard method for washing this sand prior to use in
order to minimize chloride contamination in the resulting product.  I also
need to know my options for standardized test procedures to ensure that the
sand is adequately washed prior to use.

I know that there are standards for testing soluble chloride content in
concrete, but I am looking to make sure that the sea sand doesn't introduce
the chrlorides in the first place.

Any suggestions from anyone?


Terangue *Tiger* Gillham, PE
GK2, Inc.
PO Box 8061, Koror, Palau 96940
Phone: (680) 488-7282 office
             779-6051 cellular
tiger(--nospam--at) <mailto:tiger(--nospam--at)>

The total chloride content of aggregate is usually measured to assess whether the aggregate's contribution to the total chloride content of a concrete mix will be low enough to prevent the early onset of corrosion of any embedded steel reinforcement.

The test can be conducted in a variety of chemical means, from approximate dip-stick measures through to potentiometric methods. The usual method is by titration.

ASTM C1524-02A Test Method for Water-Extractable Chloride in Aggregate (Soxhlet Method)

Using the chloride content of the aggregates, the weight of chlorides in the mixture can be
estimated and expressed as a percentage of the cement content of the mix.

The results should be
compared against the recommendations of Table 4.4.1, "Maximum Chloride Ion Content for
Corrosion Protection" in ACI 318.

This calculation is conservative, as all chlorides in the
aggregates are not soluble ions.

If the chloride content is 500 ppm or less, generally
this calculation will reveal that for normal applications the chlorides in the aggregates are not of concern.

If the calculation results in higher values, OR

 If the applications for the concrete entails
exposure to extreme corrosion conditions, further testing of the soluble chloride ion content of hardened concrete specimens from trial batches should be conducted .

A trial batch solution is cheap insurance against making a big mistake

Once you have delveloped your process, simplier testing means that you correllate with lab tests can be used as "in process" checks.