Earlier this month, NRMCA Engineering Staff Attended the ASTM meeting Committees C09 on Concrete, C01 on Cement and E05 on Fire held in Washington, DC, and filed the following report on committee activity relevant to the ready mixed concrete industry.
C09.20 Aggregates - Minor revisions were approved to ASTM C29 to measure bulk density of aggregate; to C117 to measure material finer than the No. 200 sieve and to C88 on measuring soundness of aggregate. An attempt to reference a new AASHTO volumetric method, T 354, for measuring specific gravity and absorption of fine and coarse aggregate as an alternate in ASTM C127 (coarse) and C128 (fine) was not successful.
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 progressed to main committee ballot. A revision was approved to the specification for mineral fillers, ASTM C1797, to include a test method in the Annex to measure total organic carbon in the specification. NSSGA noted that a product category rule (PCR) to develop environmental product declaration (EPD) for aggregate was released and a tool to develop EPDs has been launched.
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 to ASTM C494 and C260 will permit the qualification of admixtures using ASTM C595 Type IL (portland limestone cement) as an alternate. A revision to C494 proposes to eliminate the compressive strength requirements at 1 year for most admixture types.
C09.24 Supplementary Cementitious Materials (SCM) - The subcommittee revised ASTM C311 to refer to fly ash as coal ash. Definition of bottom ash has been added. The subcommittee is balloting changes to permit the use of Type IL cement for strength activity index of fly ash and natural pozzolans. A draft specification for natural pozzolans to address these products separately from ASTM C618 is being developed. A test method to determine the water absorption of natural pozzolans was discussed. The subcommittee has ongoing efforts to develop a specification for colloidal silica.
The subcommittee has formed a task group to create a ballot time to change ASTM C618 required LOI to “report only.” A ballot item will be created in the blended SCM specification (ASTM C1697) to remove the sulfate table and direct the user to the respective specifications of the primary SCM in the blended product. The new specification for SCMs received several negatives and will be revised and re-balloted. 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 specification limits.
The subcommittee has formed a task group to collect data on using the bulk resistivity index as an indicator to distinguish reactive SCMs from inert fillers and to establish a performance indicator for the SCMs. The subcommittee discussed the development of a guide for sulfate resistance similar to ASTM C1778. Committee C01 will be included in this process.
C09.40 Ready Mixed Concrete - Revisions approved to ASTM C94, specification for ready mixed concrete, to update the references for strength overdesign and evaluation of low strength test results and to consistently use the term “producer” instead of “manufacturer.” Other revisions in progress include revisions to reporting time and revolution limits to discharge on the delivery ticket; to remove Option C that specifies minimum cement content and to include performance properties other than strength in the ordering section; 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. Minor revisions were approved to ASTM C685, specification for volumetric batching, to include reference to some newer specifications for materials.
C09.50 Risk Management for Alkali Aggregate Reactions (AAR) - A revision has been made to the ASR concrete prism test, ASTM C1293, to make it a dual unit standard. A revision has been made to permit the use of Type IL cement in ASTM C1260, ASTM C1778 and ASTM C1293. A ballot has been developed to make the same change in ASTM C1567. The calculation of concrete alkalis in C1778 will consider the total alkali content of Type IL cement, similar to the process with C150 portland cement. The subcommittee will develop ballots to remove the alternative containers and alternative storage requirements in ASTM C1293. Ballots will be developed to remove Fig. 1 and 3 from ASTM C1778. A new alkali sensitivity test method which is based on the AASHTO T380 mini concrete prism test will also be balloted.
C09.60 Fresh Concrete Tests - Minor revisions were approved to C1064 (temperature) and to C138 (density). Revisions are in the works for ASTM C172 (sampling) to address sampling at alternate locations and to C173 (air by volumetric method) to clarify the calibration procedure. Uniform language in applicable standards has been approved regarding filling molds or containers with self-consolidating concrete in accordance with ASTM C1758. The subcommittee is developing 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). A proposal was made to permit the use of digital gages for the pressure method, similar to those used on SAM. The subcommittee is working on consistency of wet sieving of concrete containing large aggregate for the different fresh concrete tests.
C09.61 Strength - A revision was approved to the practice for making and curing strength specimens, ASTM C31, to clarify making molds with self-consolidating concrete. A revision to C39 was approved to include precision information of tests of 4 x 8-inch specimens made in field conditions. The precision is based on 9500 cylinder sets collected by NRMCA from member companies. 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. The subcommittee discussed several issues that will be proposed as revisions to C31.
C09.66 Fluid Penetration - The subcommittee made changes to add a step of 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 will propose permitting conditioning specimens in lime water. A new test method to measure the gas permeability, typically in-situ, has been developed and will be balloted.
C01.10 Cement - Some revisions approved to cement standards: removal of Type II(MH) and Type IV cements in C150, with the option for the purchaser to request heat of hydration information; removal of special property heat of hydration MH and LH in C595; permit interground limestone from interground sources and to change the requirement for limestone to accommodate dolomitic limestones (higher MgO content). Some of the approved revisions will be published concurrent with the publication of the equivalent AASHTO standards.
Items proposed for ballot or being discussed: Increase the LOI limit for blended cements to accommodate the use of natural pozzolans; clarify reporting of alkali content of components of blended cement (to support the calculation of concrete alkali loading); consider reporting oxide composition of clinker in blended cements; change the qualification of Type IL cements for sulfate resistance (to use C452 instead of C1012); change the limits for MgO in blended cements to the basis of the clinker; permit the use of two SCMs in addition to limestone in Type IT (ternary) blended cements; proposed a new type of blended cement (tentatively Type IC) that will only have a minimum limit on the clinker content; standardize the various terms used for “mill test reports” and to revise the definition of limestone for cement standards. There are initiatives to develop specifications for geopolymer and non-hydraulic cements in Committee C01.
E05.11 Fire Resistance - NRMCA presented the results of its most recent 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; 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 adapt the methodology outlined in 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 has developed 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 scope of the proposed test standard is generally limited to one - and two-family residential dwellings. The subcommittee reviewed comments received on the second ballot of this proposed standard and discussed revisions for reballot.
For more information, contact Colin Lobo or Karthik Obla for concrete and cement-related committees and Shamim Rashid-Sumar for the fire-related committee activity.
National Ready Mixed Concrete Association