NRMCA Attends Key AASHTO Committee Meeting, Files Detailed Report

NRMCA attended the recent meeting of the American Association of State Highway and Transportation Officials' (AASHTO) Committee on Materials and Pavements (COMP) held in Hartford CT, which brought together more than 200 representatives of state highway agencies and industry.

Notable developments include:

AASHTO has published its compilation of standards for 2025 that includes 585 standards.

Significant changes were noted to AASHTO R 18 on Quality Management Systems for construction materials testing labs that impacts accreditation process. AASHTO has updated its accreditation manual.

Tech Subcommittee 3a on Cementitious Materials – Larry Sutter provided an update on alternative cementitious materials and changes to ASTM standards for cements and supplementary cementitious materials. ASTM has approved a new specification for SCMs and AASHTO and ASTM have reached an agreement to standardize this in AASHTO with a reciprocal standard as a pilot effort between the two organizations.

NRMCA Executive Vice President of Engineering Colin Lobo gave a presentation on availability of cement and SCMs and some challenges with constructability and surface defects of slabs using blended cements and low carbon concrete. Several approved changes to ASTM C595 on blended cement types and requirements will be balloted for approval to revise the equivalent AASHTO M 240. AASHTO will consider developing a specification for natural pozzolans consistent with ASTM C1945. 

Tech Subcommittee 3b on Fresh Concrete – Several standards are being revised for equivalence with ASTM revisions and for reconfirmation. A revision to the specification for ready mixed concrete will permit point of sampling to be selected by the agency. The current requirement is at the point of placement. This will still be in conflict with ASTM C94 that requires sampling at the point of discharge for acceptance tests. AASHTO has a standard T 351 for visual stability index of self consolidating concrete (it's covered as a non-mandatory appendix in ASTM). It was also decided to retain the standard for air voids of fresh concrete using the air void analyzer (AASHTO T 348) as some states still use the method. AASHTO T 396, the box test for workability of paving mixtures, is being revised based on user input.

Tech Subcommittee 3c on Hardened Concrete – Revision to AASHTO T 22 to permit grinding ends of strength test specimens. A new standard is being balloted to measure the flexural response of ultra high performance concrete (UHPC) as a simpler method to AASHTO T 397 for acceptance testing. Revisions are in progress to AASHTO T 357 for chloride migration, T 358, to measure surface resistivity of concrete and T 402 to measure bulk or uniaxial resistivity.

The subcommittee is also making significant revisions to AASHTO T 380, the miniature concrete prism test for alkali silica reactivity (ASR) testing and to the practice for ASR, AASHTO R 80 based on recommendations of the recent NCHRP report 1083 on ASR. The practice will recognize using T 380 for aggregate evaluation and mitigation of ASR. An appendix will be added to R 80 to recommend criteria for using the FHWA T-FAST chemical method for evaluation of aggregates for ASR, AASHTO provisional standard TP 144.

For more information, contact Colin Lobo.