The AASHTO Committee on Materials and Pavements (COMP) met during the week of August 4 in Madison, WI, with representatives from most state highway agencies in attendance. A new compilation of AASHTO full and provisional standards was published on July 31. Technical subcommittees 3a on cementitious materials, 3b on fresh concrete and 3c on hardened concrete are working on revisions to several standards. Many of these revisions are for consistency with current versions of ASTM standards, if there are equivalent versions.
Significant revisions are in process for the specification for ready mixed concrete, AASHTO M 157, to harmonize with the equivalent ASTM C94. COMP has approved a guide for reducing embodied carbon of concrete mixtures that was developed by the Concrete Pavement Tech Center. A group of state agency personnel has recommended revisions to AASHTO R 101 on performance engineered mixtures for concrete pavements to reflect current use and also simplify some of the recommended performance tests and criteria. To address alkali silica reactivity, a new test method was approved for determining the alkali threshold level for combined aggregates to be used in concrete. The actual alkali loading (cement content x cement alkali content) should be less than the alkali threshold level.
The Federal Highway Administration provided detailed guidance for state agencies that applied to develop their requests for funding for low-carbon transportation materials. Federal funding through the Inflation Reduction Act (IRA) provided $2 billion to support agencies to incorporate eligible, substantially lower carbon materials in transportation projects. Funding can support states in establishing the process for using substantially lower carbon; modifying specifications and quality assurance processes; identify construction projects where these materials will be used and supporting the use of these materials in projects. Eligible materials include steel, glass, asphalt and concrete.
Low carbon qualification is based on a determination by the Environmental Protection Agency (EPA). Documentation of lower carbon is determined by product and facility-specific Environmental Product Declaration (EPD). Funding from this grant should be obligated to state agencies by September 2026.
For more information on developments at this meeting, contact Colin Lobo at clobo@nrmca.org.
National Ready Mixed Concrete Association