Following is a summary of activity at the ASTM Meeting held earlier this month in Atlanta of Committees C09 on Concrete and Aggregates, C01 on Cement, E05 on Fire and E36 Accreditation & Certification as reported by NRMCA Engineering Department staff.
C09.20 Aggregates - Minor revisions were approved to ASTM C70 for determining surface moisture using volumetric flask, ASTM C566 for measuring aggregate moisture by drying, and to ASTM C136 on sieve analysis. Revisions are being proposed to the methods on resistance to degradation of fine and coarse aggregate.
A proposed standard was balloted on 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. Standards for aggregates for radiation-shielding concrete, ASTM C637 and C638, were revised to characterize these as “high-density” aggregate to recognize their use in applications other than for radiation shielding.
C09.23 Chemical Admixtures - The subcommittee concentrated on preparing several ballot initiatives intended to improve technical clarity, consistency and usability of key admixture-related standards. Planned ballots focus on refining ASTM C494 by tightening the scope; clarifying the intent and classification of admixture types (including Type S and cross-qualification of Types A–F); explicitly excluding gaseous materials from the definition of chemical admixtures; eliminating vinsol resin as the reference material for air entrainment testing and adding clearer language for mid-range water-reducing admixtures, including recognition of the dual functional definition of water reducers used in practice.
Related terminology updates will be advanced through ASTM C125 to update definitions of “chemical admixture” and “specific performance admixture,” and concrete proportioning references will be updated to align with ACI PRC-211.1. The section also noted emerging technical topics for future action, including discussion of air-detraining admixtures. It was established that colloidal silica products will be addressed as an admixture, while efforts in the past have attempted to develop a specification for these products as a supplementary cementitious material.
C09.24 Supplementary Cementitious Materials (SCM) - ASTM C1945 is a new specification for natural pozzolans. Minor revisions were approved to this specification, including clarifying the types of materials that could be naturally occurring or processed by some means. This specification will include some differences in requirements from Class N in ASTM C618 (which will eventually be deleted). A new method, ASTM C1952, to evaluate reactivity of SCMs was standardized to determine the resistivity index of mortars and this method will be considered as an additional test to for SCMs.
Several revisions are in progress for ASTM C311 covering testing of coal ash and natural pozzolans. 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 is still in the works. It was noted that AASHTO has approved a new natural pozzolan spec that parallels ASTM C1945 and is in the process of approving a new SCM specification that parallels ASTM C1912.
The American Coal Ash Association has scheduled the World of Coal Ash in Lexington, KY, from May 4 - 7, 2026. The Natural Pozzolan Association has scheduled its 2027 symposium in Colorado Springs, CO, for May 25 - 27, 2027.
C09.40 Ready Mixed Concrete - Revisions approved to ASTM C94, specification for ready mixed concrete, include the deletion of Option C in the ordering information section that required a minimum cement content in addition to strength; an update to the sections on testing a preliminary sample (to make adjustments to a load); samples for acceptance testing by requiring a check test if the initial tests indicate noncompliance and to clarify that cylinders for strength acceptance should be standard cured in accordance with ASTM C31, and to include additional requirements for load cells and scale systems.
Revisions to C685 for volumetric mixers to include applicable revisions to C94 were approved. Other revisions to C94 in progress include reporting time and revolution limits to discharge on the delivery ticket. Revisions proposed to the specification for mixing water, C1602, to permit the use of seawater in concrete without metallic reinforcement were reviewed and will be re-balloted based on comments in prior ballots.
C09.48 Performance of Cementitious Materials and Admixtures - ASTM C1810 is a Guide for Comparing Performance of Concrete-Making Materials Using Mortar Mixtures. The inclusion of two new evaluation procedures was approved to evaluate causes for unexpected high air content in concrete mixtures. Updates to ASTM C1753 that uses thermal measurements from early hydration needs to be updated and leadership to support this standard. The subcommittee will work on developing precision information for the foam index test, ASTM C1827. A presentation was made proposing the addition of new bleeding test to C1810.
C09.50 Risk Management for Alkali Aggregate Reactions (AAR) - Two standards were balloted for withdrawal, but the effort was not successful because some voters wished to retain these standards. C411 is used to evaluate mitigation of alkali silica reactivity using borosilicate glass as a reference aggregate. Similarly, ASTM C586 is used to evaluate alkali carbonate reactions but is rarely used. The subcommittee will allow these to be withdrawn by not supporting any further work on these standards. Revisions to the ASR Guide, ASTM C1778, to include a revised flowchart, testing mortars with densified silica fume and other revisions are progressing. The subcommittee discussed the development of a method to measure total sulfur content of aggregates relative to the presence of pyrrhotite mineral that causes deterioration in concrete.
C09.51 Sulfate Resistance of Concrete - This newly formed subcommittee will attempt to provide guidance and harmonize how sulfate resistance is addressed in ASTM standards. The subcommittee is planning to develop a guide or practice to address requirements for sulfate resistance of concrete, similar to the guide for alkali aggregate reactions, ASTM C1778. Little progress has been made since last meeting.
C09.60 Fresh Concrete Tests - 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) was approved. The title is Test Method for Water Content in Fresh Cementitious Mixtures by Rapid Evaporation, and a new number will be assigned to the standard.
ASTM C231 for air content by the pressure method was revised to permit the use of a digital gauge. Standards for measuring slump and air content were revised to include harmonized language on wet-sieving concrete with larger aggregate based on the nominal maximum size of aggregate used. Revisions were approved to the test method for measuring bleeding of concrete, ASTM C232. Tyler Ley presented a proposed method of evaluating the finishability of concrete using a float test. A proposed test method will be developed. The subcommittee will also ballot a current AASHTO test method, T 395, Characterization of the Air-Void System of Freshly Mixed Concrete by the Sequential Pressure Method, (also known as the SAM method) to establish this as an equivalent standard in ASTM.
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 were approved to C39 (cylinder strength) to permit grinding ends of cylinders in accordance with an AASHTO standard, and C192 (making concrete in the lab) for improved clarity and use of mandatory language. A ballot proposed a reporting section to ASTM C192 (used for trial batches); NRMCA’s Schaefer will work with the task group to establish reporting details.
The subcommittee is considering the use of 90 durometer unbonded caps in ASTM C1231 for testing high strength concrete, remove the option of capping cylinders with neat cement paste and to address when cylinders can be transported if concrete is excessively retarded for setting time. Dr. Isaac Howard of (Mississippi State University) shared some work and sought support for a new ASTM method for Thermo-Mechanical Testing. This involves testing strength of insulated cylinders to obtain temperature information and evaluate impact on strength due to temperature rise, primarily for high strength or mass concrete applications. No decision was made on standardizing this concept.
C09.64 Nondestructive and In-Place Testing - A new standard, Test Method for Non-Contact Measurement of Resonant Frequencies of Concrete Cylinders, was approved. The NRMCA Laboratory has collaborated with the proponent of this method to assess/generate data. Another new standard, Air Permeability Coefficient of Hardened Concrete by Double Chamber Vacuum Cell Method, was also approved. This durability-related test method of concrete does not require knowledge or assumptions related to pore solution resistivity. Roberto Torrent (the proponent/developer of the method) conducted a post-ASTM visit to the NRMCA Lab, providing hands-on discussion and technical exchange on test execution, interpretation and practical application. Representatives from FHWA were also present to learn more about this method.
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. The test method for freeze-thaw resistance of concrete, ASTM C666, had expired and minor revisions were made to make this an active standard. Similar attempts are being made to reinstitute the scaling test, ASTM C672, that is currently expired.
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. AASHTO has approved these changes to its equivalent specification AASHTO M 240. 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). This change is being held until AASHTO approves this cement type in AASHTO M 240.
A revision was approved to increase the LOI limits for blended cements to accommodate the use of natural pozzolans and establishing the base limestone content of 15%. A revision to C595 was approved to evaluate sulfate resistance of portland limestone cement (Type IL) by ASTM C452 instead of ASTM C1012. ASTM C452 is completed within 28 days as opposed to C1012 which can take up to 18 months. C1012 is better suited to determine the efficacy of SCMs for sulfate resistance (either in a blended cement or separately added to concrete).
A limit on MgO as a percent of the clinker portion in blended cement was approved in C595 to address the potential for unsoundness of cement. The subcommittee is working on revisions to the performance-based specification for cement, ASTM C1157. Among those discussed are to determine if this cement can mitigate alkali silica reactivity; establish a type for rapid hardening cement; consider the use of alternative cements used at a very low w/cm and consider including an evaluation of shrinkage. There continues to be several other proposed changes being considered in the specifications for cements.
E05.11 Fire Resistance - The subcommittee is working on revisions to ASTM E119 Test Methods for Fire Tests of Building Construction and Materials. A proposed revision related to the determination of moisture content for concrete samples which adapts the methodology outlined in ASTM F2170, Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes, has been balloted.
The subcommittee is also working on defining the test specimen area to address ambiguities related to hose stream failures of the test and investigating alternate materials for thermocouple pads used for the test. Additional E119 items for review include clarifications on measuring uniformity of exposure in the E119 furnace; Fahrenheit to Celsius conversion for the temperature rise criteria and the duplicate hose stream test requirements in the standards. Proposed changes are anticipated to be balloted before the next meeting in June.
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 and is advancing through the standard development process.
E05.23 Combustibility - The subcommittee is considering development of a 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. NRMCA continues to monitor and oppose the development of new standards, proposing less stringent criteria for qualifying noncombustible materials.
E05 – Research Review - Two presentations were delivered by practitioners at the Committee E05 Research Review session. Samuel Manzanello presented on The Need for the World to be Prepared for the Growing Wildland-Urban Interface (WUI) Fire Threat, describing the development of firebrand generators and reviewing ISO TC92 documents related to the WUI as well as ongoing international efforts to strengthen wildfire resilience. Amy Kerr presented on Fire Performance of Aged Automotive Battery Cables Assessed via Cone Calorimetry, highlighting a study on electric vehicle battery cables undertaken at the University of Tennessee - Knoxville.
E36.70 Agencies Performing Construction Inspection, Testing and Special Inspection - The E36.70 subcommittee reviewed revisions of ASTM E329, including updates to terminology, accreditation language, nondestructive testing definitions and qualification requirements for agencies performing construction inspection and testing. The group reviewed outcomes from several recent ballots, noting which items advanced, were withdrawn or were removed for further development based on negative votes and comments.
Coordination with other committees was also discussed, including feedback from the firestop community where concerns were raised about the use of the terms “certified” and “certification,” with consideration given to alternative language such as “qualified by examination.” No new work items were initiated and near-term efforts will focus on resolving ballot issues, conducting follow-up discussions on withdrawn items and preparing upcoming ballots.
Other:
Prior to the start of the committee sessions, a one-day ASTM workshop on low-carbon concrete focused on how emerging low-carbon materials, testing methods and policy drivers are influencing cement and concrete standards. The event highlights ASTM’s role in enabling adoption through consensus-based specifications, improved testing and data transparency while addressing key topics such as EPDs, GCCA low-carbon ratings, ACI Code 323, alternative binders, SCM performance and contractor acceptance.
Overall, the workshop emphasizes that successful carbon reduction in concrete requires not only innovative materials, but also aligned standards, reliable testing and collaboration across the industry.
NRMCA staff at the December ASTM meetings included Glenn Schaefer, Colin Lobo, Shamim Rashid-Sumar (E05) and Tiffany Reed-Villarreal.
National Ready Mixed Concrete Association