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Re: ASR Repair

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Repair generally consists of patching the larger areas of damage with a mixture
of cement and an acrylic latex emulsion.  This is followed by treating the area
with a silane or methyl methacrylate sealer.  Repair methods vary at this point
depending on whether  the concrete is painted.  Reducing the water penetration
can sometimes help control and even prevent further ASR.

It is important to determine whether or not ASR has impaired the concrete
strength.  Tests should be made to determine this.  This is probably most
important in areas of unconfined concrete.

Also, some concrete studies have shown a delayed ettringite formation, or the
hydrating of calcium, may produce similar effects but is not the same. ASR is
best detected by using general optical microscopy so that it is not confused
with something else.

The presence of the reactive gel at the rim of the aggregates is generally the
only way of identifying  that ASR has developed in the concrete.  The only real
way to see this is microscipically.

Some useful direction may be as follows:
Consult some lab people from ASTM who specifically test for this.
Consult with admixture manufacturers who make products for the repair of this
type of damage.
See also from ACI, SP-131 and SP-126.  These should be available but may take
awhile to find.
Read also the Guide to durable concrete available from ACI.

Hope this helps,

Bart Needham, SE

Mark Rodgers wrote:

> I am working on a remodel and addition to a retail store.  The concrete
> parapets exhibit signs of Alkali Silica Reactivity (ASR).  The concrete has
> been tested and ASR is present.  The building was built in the 60's in
> Albuquerque, NM.
>
> I am wondering if anyone has any ideas on the repair of concrete with ASR?
>
> Thanks in Advance,
>
> Mark Rodgers. EIT
> Dekker / Perich / Sabatini
> architecture  interiors  planning  engineering
> 505 761.9700
> fax 761.4222
>