NRMCA Attends ASTM Meeting in Toronto; Reports on Key Industry Activities

The following is a summary of activity at the ASTM meeting held in Toronto in June of Committees C09 on Concrete and Aggregates, C01 on Cement and E05 on Fire attended by NRMCA staff.

C09.20 Aggregates - Notes were added to ASTM C127 and ASTM C128 (specific gravity and absorption of aggregates) to reference AASHTO method T 354 that determines these properties of aggregates by the volumetric immersion method. This method cannot be included in the ASTM standards. The method does not require bringing aggregates to the SSD condition and the precision seems to be improved.

Minor revisions were approved to ASTM C70 for determining surface moisture using volumetric flask and to ASTM C136 on sieve analysis. Revisions are being proposed to the methods on resistance to degradation of fine and coarse aggregate. The subcommittee was presented with a process of determining aggregate size, shape and texture using digital imaging of aggregates of coarser size. The assessment can be performed with an app and the camera on smart phones and is developed by Alterbiota.

C09.24 Supplementary Cementitious Materials (SCM) - A new specification for SCMs was approved. This specification will apply to alternative SCMs and to materials that fall under the scope of existing specifications like C618, C989 or C1240, but that do not comply with some requirements.

Several revisions are in progress to ASTM C1945, Specification for Natural Pozzolans, to include reactivity evaluation from ASTM C1897; inclusion of activated natural pozzolan; removal of limits on LOI but require it to be reported; remove the optional evaluation for SCM impact on drying shrinkage; change to limits on sulfate content and several other revisions, some of which have been approved.

Revisions are in progress to the specification for blended SCM, C1697: include a reference to the specification for natural pozzolan; remove the optional requirement for drying shrinkage; update sulfate resistance requirements and other revisions, some of which were approved. A proposal to permit including limestone as a component in blended SCMs did not pass at this meeting. Revisions to the sulfate resistance provisions of ASTM C1866 on ground glass pozzolan was approved.

There continues to be an effort to develop a specification for colloidal silica that was not successful at this time. The subcommittee discussed whether standards for this material should be addressed as an SCM or as a chemical admixture. These products are currently marketed as a Type S chemical admixture conforming to C494. A testing approach for pozzolanic activity that uses a simplified mixing procedure and a heat or temperature hydration curve as an indication of reactivity was discussed. NRMCA will consider evaluating proposed procedures at the NRMCA Laboratory.

C09.28 Biochar for Use in Concrete - This new subcommittee has been established to develop specifications for biochar. The effort is supported by the US Biochar Initiative and some suppliers. Biochar is developed by combustion of any form of biomass without the presence of oxygen at a temperature that exceeds 400°C. The properties depend on the feedstock used. When used in concrete, it can reduce its carbon footprint because biochar is typically documented as carbon negative. The group discussed what needs to be addressed in a specification for biochar.

C09.40 Ready Mixed Concrete - Revisions approved to ASTM C94, Specification for Ready Mixed Concrete, include revise a note regarding durability exposure classes and to include a reference to the specification for natural pozzolans was approved. Revisions to C685 for volumetric mixers to include applicable revisions to C94 were approved. Other revisions in progress include reporting time and revolution limits to discharge on the delivery ticket; to remove Option C where the purchaser specifies minimum cement content; to clarify curing of test specimens in accordance with C31 and to address retesting concrete that failed to meet slump and/or air content requirements before rejecting a load.

The subcommittee discussed proposed revisions to specification for mixing water, C1602, to permit the use of seawater in concrete without metallic reinforcement. This could be either as an addition to C1602 or developed as a separate specification.

C09.47 Self-Consolidating Concrete (SCC) - The subcommittee discussed the use of the T50 evaluation procedure for SCC. This is currently described in a non-mandatory appendix and is used as a relative measure of flow rate, viscosity and stability. ASTM C1610 permits two alternate filling procedures of the slump cone and this can impact results of the T50 evaluation. The subcommittee discussed how this could be resolved if this method is specified.

C09.50 Risk Management for Alkali Aggregate Reactions (AAR) - Revisions were approved to ASTM C1567 to permit testing with C595 blended cements, blended SCM’s conforming to C1697 and C1866 ground glass pozzolans. The test using standard pyrex glass as aggregate for evaluation of effectiveness of SCMs, C441, is being withdrawn. New data is under consideration to update the precision and bias statements for C1567 and C1260 which includes expansions <0.1%. Discussions around C1778 to de-emphasize using performance history and petrography as required first steps in the evaluation process of aggregate sources.

A general clean-up of the C1778 flow chart is being proposed. A note will be included in C1778 regarding agglomeration of silica fume and the impact on ASR test results, suggesting that petrography be performed on sample with odd results to determine if the agglomerations are causing expansion or reducing the level of effective pozzolan content.

The subcommittee discussed changing the duration of C1567/C1260 testing from 14 to 28 day, but debated on the criteria to use for results. An ASTM standard will be developed on the mini concrete prism test that is currently standardized as AASHTO T380. There was a discussion on alkali threshold values being proposed in the AASHTO practice T 80. A task group is working on the development of a test method to assess pyrrhotite expansion.

C09.51 Sulfate Resistance of Concrete - A new subcommittee will attempt to provide guidance and harmonize how sulfate resistance is addressed in ASTM standards. The subcommittee will develop a guide or practice to address requirements for sulfate resistance of concrete, similar to the guide for alkali aggregate reactions, ASTM C1778.

C09.60 Fresh Concrete Tests - Revisions are being proposed to describe consistent methods of wet sieving samples in C143 (slump) and the air content methods C173 and C231. A proposed new test method for measurement of water content of fresh concrete using a high power oven at the jobsite (referred to as the Phoenix) did not pass but is progressing toward becoming a standard. Efforts to permit the use of a digital gauge in C231 – pressure meter continue. The subcommittee had a discussion regarding the aggregate correction factor in C231 because testing labs do not typically know aggregate type and content in concrete.

C09.61 Strength - Revisions were approved to the practice for making and curing strength specimens, ASTM C31, to clarify some of the procedures and terminology used. Some revisions are being proposed to C39 (cylinder strength) and C78 (beam strength) but were not approved at this time. Minor revisions were approved to ASTM C192 (making concrete in the lab) and to the practice for accelerated curing of test specimens, ASTM C1768. The subcommittee discussed the inclusion of 90 durometer unbonded caps in ASTM C1231 for testing high strength concrete and was looking for comparative data that could support this revision.

C09.64 Nondestructive and In-Place Testing - Negatives and comments on a ballot on a new standard, Test Method for Non-Contact Measurement of Resonant Frequencies of Concrete Cylinders, was discussed. The document will be re-worked and re-balloted. NRMCA Lab has collaborated with the proponent of the testing to assess/generate data. Giatec presented information on a new maturity sensor that doesn’t require calibration with trial concrete mixtures. There was concern about the concept of this measurement and analysis that did not align with an existing standard. Data was presented on Thermographic Inspection techniques (C1060) that can be used for void detection on bridge decks and other concrete structures as an alternative to hammer sounding.

C09.66 Fluid Penetration - The subcommittee has revised ASTM C1876 to permit conditioning specimens in lime water as an alternative to using a simulated pore solution. This alternative can broaden the measurement of bulk resistivity of concrete using the common curing method for test specimens. A new test method to measure the gas permeability, typically in-situ, has been developed and negatives and comments will be addressed for a revised ballot. The NRMCA Lab has offered to collaborate with the proponent of the test method to assess/generate data to compare results from other methods measuring “permeability” of concrete.

C09.99 Innovative, Emerging, and Developing Technology - This new subcommittee was established to originally focus on Embodied Carbon and Energy Reductions. However, at the meeting the scope was changed to look at a variety of innovations/new topics. This decision was to develop a practice to lowering the embodied global warming potential of concrete construction and to discuss what should be considered in developing Environmental Product Declarations (EPD). While the focus was on EPDs, there was consensus that material extraction (A1) and transport to the manufacturer (A2) would be impractical to consider. It was noted that NIST was also developing a guide on the same topic. The subcommittee also discussed AI and whether aspects/usage/guidance on use of AI falls within the scope of this subcommittee.

C01.10 Cement - Some revisions approved to cement standards: in ASTM C595 for blended cement – cements containing up to 15% limestone can be the base cement when adding pozzolan for Type IP, slag for Type IS and adding two SCMs for Type IT. A proposal to add another cement type – Type IC for “composite” cement – will not have limits on limestone or SCMs but will require a minimum of 30% clinker. This type will support the manufacture of limestone-calcined clay cements (LC3).

A revision was approved to change the LOI requirements for components and the blended cement in C595 if this results from composition that does not impact air entrainment in concrete. A proposed revision is to include a limit on MgO as a percent of the clinker portion in blended cement to address the potential for unsoundness of cement. A revision was also approved to improve the clarity of reporting the alkali content of components and the finished blended cement. Revisions approved to ASTM C595 will be published only after AASHTO approves and publishes these revisions. The subcommittee is working on revisions to the performance-based specification for cement, ASTM C1157.

E05.11 Fire Resistance - The subcommittee is revising ASTM E119, Test Methods for Fire Tests of Building Construction and Materials. A proposed revision is related to the determination of moisture content for concrete samples and will adapt the methodology outlined in ASTM F2170, Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes. The subcommittee is also working to define the test specimen area to address ambiguities related to hose stream failures of the test. The subcommittee is investigating alternate materials for thermocouple pads used for the test. Proposed changes will be balloted before the next meeting in December.

E05.14 External Fire Exposures - The subcommittee continues its work on a new test method for determining fire propagation of exterior wall assemblies using a direct flame impingement exposure. This standard is based on ASTM E2707 and is intended to test the fire performance of exterior wall construction in Type V buildings. The proposed test method is generally limited to one-and-two-family residential dwellings.

The subcommittee has also commenced preliminary work on a new ASTM standard for fire propagation of exterior mass timber wall assemblies. Following an unsuccessful standard based on ULC S134, the new standard is proposed to follow the methodology in ISO 13785 which includes a wing wall in the test assembly and simulates fire spread in a reentrant corner. The objective is to develop a test method that would allow combustible material in exterior walls of buildings. NRMCA continues to monitor and oppose the development of new standards rivaling the NFPA 285 standard.

E05.23 Combustibility - The subcommittee continues the development of a 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. NRMCA continues to monitor and oppose the development of new standards proposing less stringent criteria for qualifying noncombustible materials.

E05 – Research Review - Three presentations were delivered by practitioners at the Committee E05 Research Review session. Marcelo Hirschler presented on Wildland Urban Interface Codes Used in the USA: Compare and Contrast, providing an overview of the various requirements for preventing fire spread in the wildland urban interface. Daniel Gorham presented on Residential Exterior Wall Reaction to Post-Flashover Compartment Fires, highlighting the role of combustibles and defensible space in residential compartment fires. Alexander Morgan provided the final presentation on New Potential Standard Reference Materials for Cone Calorimeter Testing.

Other Notable Developments:
ASTM’s highest award, the Award of Merit, was presented to Thomas Greene with Chryso by Committee C09.

Scott Orthey, ASTM staff manager who has facilitated the work of Committee C01 on Cement and C09 on Concrete and Aggregates (and other ASTM Committees) for 40 years, will retire later this year. His contribution to cement and concrete standards was recognized in a separate reception and at the various subcommittee meetings.

A workshop titled Low-Carbon Concrete: Industry Trends and their impact on ASTM Cement and Concrete Standards is scheduled for Sunday, December 7, at the next ASTM meeting at the Hilton Atlanta in Atlanta. About 25 papers have been submitted that are going through a selection process.

NRMCA staff at the June ASTM meetings included Glenn Schaefer, Colin Lobo and Shamim Rashid-Sumar (E05).