NRMCA Files Detailed Report of Recent ASTM Meetings on Concrete, Cement

NRMCA Engineering Staff has summarized key activity of a virtual ASTM meeting held earlier this month of Committees C09 on Concrete and C01 on Cement.

C09.23 Chemical Admixtures - ASTM C1017 A Specification for Flowing Admixtures has been withdrawn as products are not sold under this. The subcommittee discussed developing a method to measure chlorides in admixtures that can be referenced in the specifications. A specification for shrinkage reducing admixtures is in a draft form. Discussed if specifications were needed for hydration control admixtures (currently qualified as Type B or D in ASTM C494), slump retaining admixtures and admixtures to mitigate alkali silica reactions. The subcommittee discussed permitting the use of Type IL (portland limestone cement) for qualifying admixtures as there could be a lack of availability of ASTM C150 Type I cement in the future.

C09.24 Supplementary Cementitious Materials - A task group on pozzolanic activity determination discussed a variety of new methods and modification of existing methods to characterize the reactivity of supplementary cementitious materials (SCM) and their impact on strength and durability when used in concrete. The subcommittee has ongoing efforts to develop specifications for colloidal silica and performance-based one for SCMs. There is a proposal to remove limits for loss on ignition (LOI) for fly ash but to require that it be measured and reported. A draft specification for natural pozzolans is being developed to possibly address these products separately from ASTM C618. The subcommittee is working on the inclusion of harvested fly ash in ASTM C618 with minor changes to the requirements.

C09.40 Ready Mixed Concrete - A steering committee of the task group chairs met to discuss revisions. Some recent revisions were approved in the current version of the specification for ready mixed concrete, ASTM C94-21b: removal of a numerical limit for time to discharge, an indication that the purchaser should indicate if there is a max temperature for concrete with a note indicating that 95F was specified in ACI standards; revision to measurement accuracy of batch water and a reference to ASTM C1876 that permits the use of ground glass pozzolans. Revisions proposed to ASTM C94 include revise reporting requirements for limits to discharge on the ticket (revs and time); include a requirement to report permitted jobsite water on the delivery ticket; revision to Note 22 regarding max temperature in hot weather; address retesting if slump and air fail specified requirements; include references to C1697 for blended SCM and C1798 for mineral filler as well as the accuracy for batching; revising the appendix table on strength overdesign, and consistent use of the words purchaser and manufacturer. There are several other minor revisions progressing for ASTM C94 and the standards for mixing water ASTM C1602 and C1603.

C09.50 Risk Management for Alkali Aggregate Reactions (AAR) - The subcommittee has some revisions in progress to ASTM C1778 to include a reference to the use of ground glass pozzolan with an indication that types with high alkali (Type GS) should be evaluated by ASTM C1293 for a 2-year period; revisions to incorporate guidance on interpretation of results C1778 while deleting the appendix of ASTM C1567. Several possible new business items were discussed.

C09.61 Strength - The subcommittee is resolving negatives on a revision to clarify loading rate on beams and a tolerance on the specified test age in ASTM C78. A proposal to require measuring density of fresh concrete when casting cylinders received several negatives that are being addressed. Several other revisions to ASTM C31 are being addressed through balloting. Revisions to ASTM C469 (modulus of elasticity) will include precision statement and revisions will be proposed to update the method for measuring creep, ASTM C512. A precision statement for 4 x 8 in cylinders made in the field has been developed from about 10,000 tests from various sources and will be proposed as a revision to ASTM C39. The subcommittee discussed other items of new business.

C09.66 Fluid Penetration - An attempt to withdraw ASTM C642 met some resistance and some minor revisions will be proposed to retain it as an active standard. The subcommittee resolved negatives related to revisions to ASTM C1202 (rapid chloride permeability) relative to specimen thickness used in the calculations for the result. A proposed revision to ASTM C1556 whereby the cast surface should be discarded before conditioning the specimen received negatives that need to be resolved in a re-ballot. Standards ASTM C1757 and ASTM C1792 have been withdrawn. Preliminary results from the ASTM round robin program on surface resistivity, bulk resistivity, ASTM C1202 and ASTM C1556 were presented and discussed. NRMCA participated in the RR program. NRMCA presented results developed at the NRMCA laboratory relative to conditioning of test specimens for the resistivity test.

C01.10 Hydraulic Cement - The subcommittee addressed one negative on a revision to remove the autoclave expansion test that measures soundness of cement in ASTM C150. The subcommittee received updates on developments in the Canadian standards for cement, the AASHTO-ASTM harmonization group, and the AASHTO NTPEP program established to test cement sources that could be required by some state DOTs. The subcommittee discussed a need to accommodate cementitious materials that were not hydraulic such as alkali activated material in current or new specifications.

For more information, contact Colin Lobo at clobo@nrmca.org or Karthik Obla at kobla@nrmca.org.