AASHTO T303

Full Name

AASHTO T303 – Standard Method of Test for Accelerated Detection of Potentially Deleterious Expansion of Mortar Bars Due to Alkali-Silica Reaction

Scope

AASHTO T303 is a standard test method designed to quickly identify the potential for harmful expansion in mortar bars caused by the alkali-silica reaction (ASR). ASR is a chemical reaction between certain reactive aggregates and alkalis in cement, which can lead to cracking, expansion, and deterioration of concrete structures. Early detection of ASR potential is crucial for selecting suitable aggregates and implementing preventive measures to ensure the long-term durability of concrete.

Key aspects of AASHTO T303:

  • Purpose: the primary objective is to assess the potential of aggregates to undergo ASR and cause deleterious expansion within a relatively short timeframe (16 days). This accelerated test provides valuable information for making timely decisions about aggregate selection and mitigation strategies.
  • Test Procedure: mortar bars containing the test aggregate and a high-alkali cement are prepared and stored in a solution of sodium hydroxide at elevated temperature. The length change of the mortar bars is monitored over 16 days, and the expansion is compared to specified limits.
  • Interpretation: if the expansion exceeds the specified limit, the aggregate is considered potentially reactive and may require further testing or the use of mitigation measures, such as low-alkali cement or supplementary cementitious materials (SCMs).
  • Significance: AASHTO T303 is a valuable tool for identifying potentially reactive aggregates before they are used in construction. This helps prevent costly repairs and ensures the long-term performance of concrete structures.

Applications of AASHTO T303:

  • Aggregate evaluation: this test is routinely used by aggregate producers and construction agencies to assess the ASR potential of aggregates.
  • Project specifications: many construction specifications require aggregates to pass the AASHTO T 303 test to ensure the durability of concrete structures.
  • Research and development: the test method is also used in research and development to investigate the mechanisms of ASR and develop new mitigation strategies.

AASHTO T303 Accredited Laboratory

Applied Testing & Geosciences, LLC is accredited for performing tests using the AASHTO T303 standard.

Our laboratory offers comprehensive aggregate testing services, including the AASHTO T303 test for accelerated detection of ASR potential. Our experienced technicians utilize standardized procedures and calibrated equipment to provide accurate and reliable results for your construction projects.

Contact us for more information.

Resources

Keywords

alkali-silica reaction; mortar bar; expansion; aggregate; deleterious expansion; high-alkali cement; sodium hydroxide solution; length change

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