NRMCA Attends ASTM Committee Meetings, Files Detailed Report

Following is a summary of activity at the ASTM meeting held earlier this month in Denver of Committees C09 on Concrete and E05 on Fire attended by NRMCA staff.

C09.20 Aggregates - Revisions are in progress to methods for measuring specific gravity and absorption of fine (C128) and coarse (C127) aggregates and to ASTM C29 to measure bulk density of aggregate and to C117 to measure material finer than the No. 200 sieve. A new AASHTO volumetric method, T 354, for measuring specific gravity and absorption of fine and coarse aggregate will be referenced as an alternate in the ASTM standards. In ASTM specification C33 the limits on minus No. 200 sieve for coarse aggregates has been added to the grading table and removed from the deleterious substances table. The subcommittee will ballot a revision to specification C33 to simplify the limits for deleterious materials for coarse aggregate by eliminating the durability class designations based on U.S. weathering zones. A revision will be proposed to the specification for mineral fillers, ASTM C1797, to include a test method to measure total organic carbon in the specification.

C09.23 Chemical Admixtures - The subcommittee is working on specifications for anti-washout, shrinkage reducing and ASR control admixtures in various stages of development. Revisions are being proposed to ASTM C494 and C260 to permit the qualification of admixtures using ASTM C595 Type IL (portland limestone cement) as an alternate and to eliminate the strength requirements at 1 year for most admixture types. Admixtures meeting requirements at 6 months do not fail the 1-year strength requirements.
C09.24 Supplementary Cementitious Materials (SCM).

The subcommittee is balloting changes to allow the use of Type IL cement to determine strength activity index of fly ash and natural pozzolans. A draft specification for natural pozzolans to address these products separately from ASTM C618 will be balloted prior to the next ASTM meeting. It was discussed that natural pozzolans often absorb water much like aggregates and can result in a higher water demand when used in concrete. The subcommittee has ongoing efforts to develop a specification for colloidal silica. Options to change ASTM C618 to increase the availability of fly ash by changing required LOI and fineness to “report only” were discussed. Options to allow manufactured SCMs in ASTM C618 was also discussed.

A ballot to change the blended SCM specification (ASTM C1697) to allow blending of off-spec material that meets the scope of the respective SCM specifications was discussed. The sulfate table will be removed and the user will be directed to the respective specifications of the primary SCM in the blended product. The new standard specification for SCMs will be balloted to allow materials that do not meet the respective specification limits but that do meet the scope of the existing standards.

Karthik Obla presented NRMCA lab experimental work on the performance of 5 natural pozzolans, fly ashes, slag and fillers, and the value of using a bulk resistivity index as an indicator to separate the SCMs from fillers and also provide a performance indicator for the SCMs. The subcommittee agreed to develop a new test method for the bulk resistivity index as part of the reactivity test methods. ASTM E50 Guide for Assessing Harvested Ash has been developed. A fly ash PCR (product category rule) has been developed by the American Coal Ash Association and independent fly ash marketers will be developing their own EPDs.

C09.40 Ready Mixed Concrete - Revisions approved to ASTM C94, Specification for Ready Mixed Concrete, include reference to specifications for color pigments (C979) and corrosion inhibitors (C1582), and to change the term “fly ash” to “coal ash” as approved in ASTM C618. Other revisions in progress include process of reporting time and revolution limits to discharge on the delivery ticket; clarification to the strength overdesign guidance in the appendix; to consistently use the term producer instead of manufacturer; to include performance properties other than strength in the ordering; include reference to other new material specifications; to include the quantity of water permitted to be added to the batch at the jobsite; and to address retesting concrete that failed to meet slump and/or air content requirements before rejecting a load.

C09.50 Risk Management for Alkali Aggregate Reactions (AAR) - A revision to the ASR concrete prism test, ASTM C1293, to make it a dual unit standard is making progress. Results from the interlaboratory study to evaluate the impact of using Type IL cement in ASTM C1260 and ASTM C1567 were discussed. The results showed the use of Type IL cement resulted in similar or slightly lower ASR expansions and resulted in slightly higher variability in one case. Precision statements are being developed and a new ballot to allow the use of Type IL cements in ASR tests will be issued. In the ASTM C1293 concrete prism test, the alkali of the Type IL cement which includes the alkali contribution from the limestone will be used in the calculation and the alkali content will be expressed as a percent of the Type IL cement. The subcommittee discussed balloting the removal of ASTM C441 which measures the effectiveness of SCMs using a standard glass aggregate as it is likely not being used. There was a discussion of adding a note on silica fume agglomerations and modifying the mortar mixing procedure to prevent such agglomerations.

C09.60 Fresh Concrete Tests - Revisions are in the works for ASTM C172 (sampling) to address obtaining samples at placement locations, C143 (slump), C173 (air by volumetric method) to clarify the calibration procedure, C138 (density), C231 (air by pressure method) and C1064 (temperature). A precision statement will be proposed for the K-slump method (C1890). Uniform language in applicable standards has been approved regarding filling molds or containers with self-consolidating concrete in accordance with ASTM C1758 – molds are filled in one layer without consolidation as with conventional concrete. A proposal was made to the subcommittee to develop standards for the sequential air meter (SAM) and the measurement of water content of fresh concrete using a high power oven at the jobsite (referred to as the Phoenix).

C09.61 Strength - A revision was approved to the practice for making and curing strength specimens, ASTM C31, to address cylinder size based on aggregate size and to include new terminology to define curing procedures. Revisions are being developed for standards for capping – C617 to eliminate the method to cap fresh concrete with neat cement paste and C1231 to permit unbonded caps with higher durometer hardness. A revision to the precision statement of C39 for 4 x 8-inch specimens made in field conditions will be balloted. The precision is based on 9500 cylinder sets collected by NRMCA from member companies.

C09.66 Fluid Penetration - The subcommittee discussed ballot responses to allow rinsing the specimens conditioned in simulated pore solution under tap water before measuring bulk resistivity in ASTM C1876 as it considerably improved the precision and improved the stability of the measurement. A new ballot to allow conditioning specimens in lime water will also be developed. The poor precision measured in the diffusion test (ASTM C1556) was discussed.

E05.11 Fire Resistance - NRMCA presented the results of its ballot to revise ASTM E119 Standard Test Methods for Fire Tests of Building Construction and Materials. The proposed revision seeks to provide clarifications to ASTM E119 Table X3.1 Guide for Determination of Restrained and Unrestrained Conditions of Construction. The clarifications are proposed for concrete framing based on language and terminology used in current engineering and construction practice and are intended to avoid over-conservative estimations for fire resistance of concrete structural elements. The subcommittee reviewed the comments received and revisions to address these comments are in progress.

The E05.11 Subcommittee is also reviewing revisions to ASTM E119 related to the determination of moisture content for concrete samples. The revisions will consider standard approaches to confirming the moisture content, such as ASTM F2170 Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes.

E05.14 External Fire Exposures - The development of the proposed Standard Test Method for Determining Flammability of Exterior Wall Assemblies for Mass Timber Multi-Story Structures has been halted indefinitely due to copyright concerns with ULC S134 Standard Method of Fire Test of Exterior Wall Assemblies.

The subcommittee is proceeding with development of a proposed new standard test method for determining fire propagation of exterior wall assemblies using a direct flame impingement exposure. This standard is based largely on ASTM E2707 and is intended to test the fire performance of exterior wall construction in Type V buildings. The proposed test standard is anticipated to impact one-and-two-family residential dwellings. The subcommittee reviewed comments received on the first ballot of this proposed standard and discussed refinement of the scope, performance classes, fuel size and test duration of the proposed standard.

E05.22 Surface Burning - The subcommittee discussed the harmonization of UL 273 Test for Surface Burning Characteristics of Building Materials with the companion ASTM standard (ASTM E84) as it pertains to interpretation of results for multiple tests.

E05.23 Combustibility - The subcommittee discussed an issue related to detachment of thermocouples for some materials tested under ASTM 136 Standard Test Method for Assessing Combustibility of Materials Using a Vertical Tube Furnace at 750°C. The subcommittee is considering development of a proposed new standard for determining combustibility using a single thermocouple to measure temperatures over the duration of the test in lieu of the two thermocouples currently required.

E05 – Research Review - Three presentations were delivered by practitioners at the E05 Research Review session. The presentation on The Vulnerability of Decks to Embers and Flames reviewed current research on this topic and reviewed the new standard under development by the ASTM E05.14 Subcommittee on Exterior Fires based on this research. A second presentation, Better Exhaust Flow Measurements for Large-Scale Calorimetry, examined the accuracy of exhaust flow measurement and uncertainty of calorimetry measurements for large fire tests. The final presentation, Improved Mass Loss Rate Calculations discussed the use of improved methods to calculate the mass loss rate from mass loss data obtained in small-scale and large-scale calorimeter test as an alternative to the five-point formula in ASTM E1354, ASTM E1623, ASTM E2102 and other applicable ASTM standards.

For more information, contact Karthik Obla at kobla@nrmca.org or Shamim Rashid-Sumar at ssumar@nrmca.org.