AASHTO T157
Full Name
AASHTO T157 – Standard Method of Test for Air-Entraining Admixtures for Concrete
Scope
AASHTO T157 is a standard test method used to evaluate the performance of air-entraining admixtures (AEAs) in concrete. AEAs are chemical compounds added to concrete mixtures in small amounts to introduce and stabilize microscopic air bubbles throughout the hardened concrete. These entrained air voids play a critical role in enhancing concrete’s durability and resistance to freeze-thaw cycles, scaling, and deicer salt damage.
Key aspects of AASHTO T157:
- Purpose: the primary goal of AASHTO T157 is to assess the effectiveness of AEAs in entraining the desired amount of air in concrete while maintaining other essential properties such as strength and workability.
- Test procedure: the method involves preparing concrete mixtures with and without the AEA under controlled laboratory conditions. The air content of the fresh concrete is measured using standard test methods like the pressure method or the volumetric method. Additionally, the effect of the AEA on bleeding, setting time, and compressive strength of the concrete is also evaluated.
- Performance requirements: AASHTO T157 specifies the performance requirements for AEAs, including the minimum and maximum allowable air content, the permissible range for bleeding, and the minimum compressive strength of the concrete containing the admixture.
- Significance: the use of AEAs that comply with AASHTO T157 ensures that the concrete produced has the necessary air-void system for enhanced durability and resistance to harsh environmental conditions. This is particularly important in regions with freezing temperatures and deicing salt usage.
Applications of AASHTO T157:
- Quality control: cement and concrete producers use AASHTO T157 to verify the quality and performance of AEAs before incorporating them into their products.
- Product development: AEA manufacturers utilize this test method in the research and development of new and improved air-entraining admixtures.
- Specification compliance: construction projects often require the use of AEAs that meet the criteria specified in AASHTO T157 to ensure the long-term performance and durability of concrete structures.
AASHTO T157 Accredited Laboratory
Applied Testing & Geosciences, LLC is accredited for performing tests using the AASHTO T157 standard.
Our laboratory offers comprehensive testing services for air-entraining admixtures based on AASHTO T 157 and other relevant standards. Our experienced technicians conduct precise laboratory tests to evaluate the air-entraining properties and performance of your admixtures, ensuring they meet the required specifications and contribute to the durability of your concrete structures.
Contact us for more information.
Resources
Keywords
air-entraining admixture; concrete; air content; bleeding; compressive strength; scaling resistance; freeze-thaw resistance; durability; workability