ASR TEST METHODS
Our consultants and laboratory experts implement various techniques to assess the potential for alkali-silica reaction (ASR), utilizing both standardized and innovative testing methods to evaluate the potential for deterioration in new and existing structures.
STANDARDS
Standard Guide for Petrographic Examination of Aggregates for Concrete
This guide is used for the identification of rocks and minerals for use in concrete, ASTM C295 provides guidance for detecting constituents that are deleterious to concrete. The analysis is used to identify:
• Chemically Unstable Minerals • Alkali-Silica & Alkali-Carbonate Reactive
• Volumetrically Unstable Materials Constituents
• Freeze Thaw Susceptible Aggregates • Aggregates that Negatively Impact • Aggregates Containing Iron Sulfide Water & Paste Demand
Durability Engineers performs petrographic analysis to assess the compliance of aggregates with local, state, and federal project specifications.
Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method)
This laboratory test is used for the rapid assessment of an aggregate's susceptibility and potential for degradation associated with alkali-silica reaction (ASR). In this method, mortar bar specimens are stored at 80°C and submerged in a sodium hydroxide (NaOH) solution to create a highly alkaline environment. The mortar-bar test delivers results within 16 days, indicating the potential for deleterious ASR in the aggregate.
Standard Test Method for Determination of Length Change of Concrete Due to Alkali-Silica Reaction
This laboratory test is used to assess coarse or fine aggregate's susceptibility and potential for degradation associated with alkali-silica reaction (ASR). The test duration is 12 to 24 months long depending if supplementary cementitious materials are incorporated into the mixture. This test is often required by federal and state DOTs for acceptance of new aggregate sources. ASTM C1293 expansion results should serve as a basis for a decision as to whether precautions should be taken against excessive expansion due to ASR.
Standard Test Method for Determining the Potential Alkali-Silica Reactivity of Combinations of Cementitious Materials and Aggregate (Accelerated Mortar-Bar Method)
This laboratory test is used for the rapid assessment of an aggregate's susceptibility to ASR combination with supplementary cementitious materials (SCMs). Prepare in the same manner as ASTM C1260, the only variation is the incorporation of SCMs such as fly ash, slag cement or silica fume. It is recommended to run this test in tandem with the same aggregate being evaluated via ASTM C1260. If the SCM replacement has a high alkali content, ASTM C1293 is suggested for more accurate results.
Standard Guide for Reducing the Risk of Deleterious Alkali-Aggregate Reaction in Concrete
This guide provides recommendations for identifying the potential for alkali-silica reaction (ASR) and selecting preventive measures, using either prescriptive or performance-based approaches, to minimize the risk of deleterious reactions. The level of prevention depends on factors such as the reactivity of the aggregate, exposure conditions, moisture availability, the criticality of the structure, and the alkalinity of the cement.
Standard Practice for Petrographic Examination of Hardened Concrete
The standard practice for performing petrographic examination on hardened concrete, ASTM C856, is the industry standard for the evaluation of hardened concrete samples. This method is often used for identifying various issues, including but not limited to:
• Strength Issues • Delamination
• Dying & Plastic Shrinkage • Blistering
• Scaling • Mixture Compliance
Furthermore, ASTM C856 is the only application by which progressive mechanisms of distress can be formally discerned. Mechanisms such as:
• Freeze-Thaw • Corrosion
• Chemical Attack • Sulfate Attack
• Alkali-Silica Reaction & Alkali-Carbonate Reaction