NRMCA Attends Key ASTM Committee Meeting, Files Detailed Report

Following is a summary of activity at the ASTM meeting held earlier this month in New Orleans filed by NRMCA Engineering Staff.

ASTM Committee C09 on Concrete and Concrete Aggregates - presented the Katharine and Bryant Mather Member Contribution Award to NRMCA engineer Dr. Karthik Obla. The award citation reads for outstanding contributions in pioneering standards for pervious concrete as well as many contributions to supplementary cementitious materials, chemical reactions, ready mixed concrete, self-consolidating concrete, concrete’s resistance to fluid penetration and the enhancement of cement and concrete technology standards (see separate E-NEWS item directly below).

C09.20 Aggregates - Revisions are in progress to methods for measuring specific gravity and absorption of fine (C128) and coarse (C127) aggregates; to ASTM C29 to measure bulk density of aggregate and to C117 to measure material finer than the No. 200 sieve. The subcommittee will propose a clarification to ASTM C136 on sieve analysis to address the difference between the original sample weight and the total weight after sieving. A revision to the specification for mineral fillers, ASTM C1797, to remove a requirement to measure total organic carbon is in progress. The subcommittee continues to work on simplifying the deleterious material limits for coarse aggregates and to possibly remove the map representing weather regions in the U.S. and to replace this with exposure class definitions.

C09.23 Chemical Admixtures - The subcommittee is working on specifications for anti-washout, shrinkage reducing and ASR control admixtures in various stages of development. Because of anticipated limited availability of ASTM C150, Type I or II cements, the subcommittee will propose permitting the qualification of admixtures in ASTM C494 and C260 using ASTM C595 Type IL (portland limestone cement) as an alternate.

C09.24 Supplementary Cementitious Materials (SCM) - A revision was approved to ASTM C618, specification for fly ash to include harvested fly ash. The definition of coal ash now includes fly ash, harvested ash and ground bottom ash. The subcommittee discussed a limit for the ASTM C1897 SCM reactivity test that will differentiate inert materials from reactive materials which will be balloted in the new generic specification for SCMs. The subcommittee has ongoing efforts to develop a specification for colloidal silica. A proposal to remove limits for loss on ignition (LOI) for fly ash but to require that it be reported was not successful.

The use of Type IL cement to determine strength activity index of fly ash and natural pozzolans was discussed. A draft specification for natural pozzolans is being developed to possibly address these products separately from ASTM C618. It was discussed that natural pozzolans often absorb water much like aggregates and can result in a higher water demand when used in concrete.

C09.40 Ready Mixed Concrete - A minor revision was approved to ASTM C94, specification for ready mixed concrete, to clarify conditions on adjustments to loads in transit or at the jobsite. 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; removing Option C in the ordering section that includes a minimum cement content; to include performance properties other than strength in ordering Option A; include reference to some new material specifications; to request Environmental Product Declarations (EPD) when ordering concrete; and to address retesting concrete that failed to meet slump and/or air content requirements before rejecting a load.

A proposal to consistently use the term manufacturer for the concrete producer in the specification was not supported. The subcommittee will propose a revision to consistently use the term producer in C94. A revision to the testing the density and solids content of mixing water from non potable sources, ASTM C1603, was approved.

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. The subcommittee has organized an interlaboratory study to evaluate the impact of using Type IL cement in ASTM C1260. The program will evaluate expansion results with Type I and Type IL with three aggregate types. ASTM C1567 will also be evaluated optionally at one fly ash dosage. These test methods will also get an updated precision statement. The NRMCA Research Laboratory will participate in the testing. The subcommittee discussed balloting the removal of ASTM C441 which measures effectiveness of SCMs using a standard glass aggregate, as it is likely not being used.

C09.60 Fresh Concrete Tests - Several standards need revisions to maintain a current date version. Uniform language in applicable standards will be included 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. The subcommittee discussed process of verifying vibrator frequency when used for consolidation of concrete in test specimens.

C09.61 Strength - A comprehensive proposed revision to the practice for making and curing strength specimens, ASTM C31 to address cylinder size based on aggregate size and to include new terminology received several negatives that will be addressed in a revised ballot. There are several standards under this subcommittee that need some minor revisions in order to renew them for a current date requirement. ASTM requires that standards that have not been revised for eight years be removed. These include standards for capping – C617 and C1231, measurement of creep, C512, method for strength of cast-in-place cylinders, C873 and some other standards.

The subcommittee decided to not revise or reapprove the measurement of flexural strength by single point loading, C293. Frequency of measuring diameter of specimens for strength tests was discussed and this may be clarified in C39. A revision will better define the gage length used for calculation of modulus of elasticity in C469. 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.

C09.66 Fluid Penetration - Results from the ASTM inter-laboratory study on surface resistivity (AASHTO T 358), bulk resistivity (ASTM C1876), rapid chloride permeability (ASTM C1202) and bulk diffusion (ASTM C1556) were presented and discussed. The NRMCA lab participated in the ILS program and helped develop the guidelines and interpret the data. NRMCA lab’s original observation of unstable readings when measuring bulk resistivity for specimens immersed in simulated pore solution was confirmed by other labs.

Rinsing the specimens in water before the measurement marginally increased the measured resistivity but considerably reduced the variation related to the stability of the measurement. Conditioning specimens in lime water indicated lower variability though not as low as the rinsed specimens. Some labs cured specimens in the moist room which resulted in higher variability. The subcommittee agreed to include a requirement to rinse specimens conditioned in simulated pore solution and to add an alternative for specimens to be cured in lime water in C1876. The precision of the RCP test (ASTM C1202) was considerably better than that published in the current standards. The precision of the diffusion test (ASTM C1556) is still being analyzed.

C01.10 Hydraulic Cement - A proposal to remove low heat of hydration characterization and Type IV cement in C150 and C595 (MH and LH designations) was tabled because it was identified that commercially available cements outside the U.S. need these to be retained. A limit on the autoclave expansion test was removed from C595 as it has been from ASTM C150 and some other standards. The subcommittee will consider removing this limit from ASTM C1157. A proposal to permit use of limestone or calcium carbonate additions to portland and portland limestone cements from non-quarried sources was considered and there were some concerns expressed. This will be re-evaluated and alternate criteria for these sources will be proposed. Limestone interground in portland and blended cement currently needs to be from quarried rock with a minimum calcium carbonate content.

E05.11 Fire Resistance - NRMCA presented its ballot and results for a revision of 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 E05.11 Subcommittee is also reviewing requirements within the ASTM E119 test standard regarding reporting on deflection of structural members and addressing conflicts among different provisions in the standard.

E05.14 External Fire Exposures - The subcommittee recently re-balloted a revised version of the proposed Standard Test Method for Determining Flammability of Exterior Wall Assemblies for Mass Timber Multi-Story Structures. Data was presented with the intent of demonstrating higher heat fluxes implying a more severe fire exposure for the proposed new test method in comparison with the fire exposure conditions of NFPA 285, Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Wall Assemblies Containing Combustible Components. The ballot received several negative votes and questions were raised regarding inconsistencies with heat flux measurements provided versus accepted calibration heat flux values. The proposed standard is expected to be re-balloted in 2023.

E05 Research Review - Three presentations were delivered by practitioners at the E05 Research Review session on the topic titled Limiting Fire Spread at Exterior Walls of Buildings. The presentations reviewed the evaluation of spread of fire from exterior wall assemblies (NFPA 285), the evaluation of performance of building spandrel panels from external fire exposure (ASTM E2874) and preventing interior fire spread through the joint at the non-rated exterior wall/floor slab intersection (ASTM E2307). The three test methods utilize a similar two-story scale test assembly. The presenters reviewed case studies of fires and provided benefits and limitations of the respective test methods in preventing fire exposure and spread.

For more information on activities at Committees C01 and C09, contact Karthik Obla or Colin Lobo; for E05 contact Shamim Rashid-Sumar.