Alkali-silica reaction (ASR)

Alkali-silica reaction (ASR) is a chemical reaction that can cause concrete to crack and deteriorate prematurely. ASR occurs when certain aggregates in concrete react with the alkali hydroxide in the concrete to form a gel. The gel can swell and put enough pressure on the concrete to cause it to crack.

Wild West Custom Pools uses a tested mix of concrete to ensure the mixture is non-reactive. Our Sub Contractor monitors the mix to ensure compliance to appropriate concrete standards.

See the testing results below.

Per your request, Wiss, Janney, Elstner Associates, Inc. (WJE) performed laboratory testing of a
combination of aggregate and cementitious materials to assess the susceptibility of the material
combination to potential alkali-silica reactivity (ASR). Accordingly, the materials were evaluated based on
ASTM C1567, Standard Test Method for Determining the Potential Alkali-Silica Reactivity of Combinations
of Cementitious Materials and Aggregate (Accelerated Mortar-Bar Method)
SAMPLES AND TESTS
Received for the project was one bag of blended aggregate without identification and a bucket of
blended cementitious materials identified as “IT, Silo-1, 5-3-24.” No information about the source of the
aggregate was provided. No information regarding the components and proportion of the blended
cementitious materials was provided.
For ASTM C1567 testing, an appropriate amount of the blended aggregate was obtained, washed, and
regraded, as required by the test method. One mortar mix using the prepared aggregate and the
provided blended cementitious materials was batched based on the mix proportions prescribed by ASTM
C1567. The aggregate-to-cementitious materials ratio and the water-to-cementitious materials ratio were
fixed by the test method. Three mortar bars measuring 1 inch by 1 inch by 11-1/4 inches were cast. The
mortar bars were cured in molds in an environmental chamber for 1 day, followed by tap water curing at
80 degrees Celsius for 24 hours. After the initial curing period, the bars were stored in 1N sodium
hydroxide (NaOH) solution at 80 degrees Celsius for 14 days (16 days from the time of mixing), and the
length changes of the bars were measured periodically.
FINDINGS
The results of ASTM C1567 testing are given in Table 1 and Figure 1. The average expansion of the mortar
bars after 14 days in the NaOH solution (16 days from the date of mixing) was 0.01 percent.
CONCLUSIONS
Based on the ASTM C1567 testing, the materials combination had a 14-day (16 days from the time of
mixing) expansion rate of 0.01 percent. Based on ASTM C1778, Standard Guide for Reducing the Risk of Deleterious Alkali-Aggregate Reaction in Concrete, combinations of cementitious materials and aggregates
will be deemed acceptable for use if the resulting expansion is less than 0.10 percent after 14-day
immersion in 1M NaOH. Therefore, the aggregate and the cementitious materials combination
represented by the samples are innocuous (non-reactive).
We appreciate the opportunity to assist you on this project. If more assistance is needed, please do not
hesitate to contact us.
Sincerely,
WISS, JANNEY, ELSTNER ASSOCIATES, INC.