W. CONSHOHOCKEN, PA., – Proposed new standards for aggregate resistivity, lightweight aggregates, methacrylate bonding systems, and semi-adiabatic calorimetry are among those currently being developed by subcommittees under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregates. All interested parties are invited to participate in the standards developing activities of ASTM Committee C09 subcommittees.
Aggregate resistivity – Reinforcement embedded in embankment walls during construction is affected by the environment’s resistance to corrosion. A proposed new test method will be useful in measuring how resistant the aggregate used for such reinforcement will be. ASTM WK24621, Test Method for Measurement of Aggregate Resistivity Using the Two-Electrode Soil Box Method, is being developed by Subcommittee C09.20 on Normal Weight Aggregates.
John Yzenas, director, Technical Services SMSG, Edward C. Levy Co., and a member of Committee C09, said that, in addition to Subcommittee C09.20, Subcommittee G01.10 on Corrosion in Soils, part of ASTM International Committee G01 on Corrosion of Metals, has also been involved in the development of ASTM WK24621.
"G01.10’s original work resolved many questions that previous test methods had left unanswered, such as adequate description of 100-percent saturation, ability to test various size materials, and testing materials in ‘as-received’ condition," said Yzenas. "This proposed test method is a variation of G01.10’s work, dealing specifically with aggregate."
Yzenas noted that, upon its approval, ASTM WK24621 will be useful to designers, specifiers, and testing companies because current corrosion test methods are based on soils and may not adequately characterize aggregates.
Lightweight aggregates – The proposed new standard, ASTM WK23421, Specification for Lightweight Aggregates for Internal Curing Applications, is being developed by Subcommittee C09.21 on Lightweight Aggregates and Concrete because lightweight aggregates are used differently during the internal curing process than when they are used for other purposes.
"Instead of using lightweight aggregates to reduce the density of the concrete, the pre-wetted or preconditioned lightweight aggregates are used in relatively small quantities in high-performance normal weight concrete to provide internal moisture reservoirs throughout the cross-section of the concrete," said Jeffrey Speck, vice president-sales and marketing, Big River Industries Inc., and chair of C09.21.
Speck said that users of ASTM WK23421, once it is approved, will be design engineers who are designing structures built of concrete with a very low water/cementitious materials ratio and by concrete producers supplying the concrete for such structures.
Highway engineers will also find the proposed standard useful, since lightweight aggregates used for internal curing are proving to be effective in reducing concrete pavement cracking.
Methacrylate bonding systems – Methacrylate is used to strengthen and fortify finely cracked concrete and to minimize the ingress of contaminants such as chlorides and deicing salts that could further degrade concrete. Once approved, a proposed new standard, ASTM WK24405, Specification for Reactive Methacrylate Bonding Systems for Concrete, will provide guidance on relevant properties for these bonding systems and how to evaluate such properties to enable users to determine acceptable material performance.
ASTM WK24405 is being developed by Subcommittee C09.25 on Organic Materials for Bonding. According to Quentin Hibben, senior research chemist, Simpson Strong-Tie Anchor Systems, and a member of the subcommittee, the proposed new standard will primarily be used by specifiers, engineers, and material producers for bridge maintenance, parking deck, and airport tarmac projects. Departments of transportation could also potentially use the proposed standard for a variety of projects.
Hibben noted that the subcommittee is seeking input and guidance for relevant properties and acceptable values for low-viscosity methacrylate-based resin systems, as well as assistance in reproducibility testing.
Semi-adiabatic calorimetry – Thermal measurements of hydrating cementitious mixtures, referred to as semi-adiabatic calorimetry (SAC), can be used to evaluate behavior of concrete mixtures and concrete-making materials, as well as for troubleshooting certain types of abnormal concrete performance. Interest in using SAC for these purposes has grown in recent years, along with increased availability of both generic hardware that can be used for SAC and manufactured systems designed specifically for the process.
A proposed new standard, ASTM WK23967, Practice for Measuring Hydration Kinetics of Hydraulic Cementitious Mixtures Using Semi-Adiabatic Calorimetry, will help guide users in planning and implementing productive SAC testing programs for concrete mixture evaluation. WK23967 is being developed by Subcommittee C09.48 on Performance of Cementitious Materials and Admixture Combinations.
Tim Cost, senior technical service engineer, Holcim (U.S.) Inc., and chair of the task group that is developing the practice, said that, when approved, ASTM WK23967 will provide standard protocols for conducting tests that will help assure meaningful and repeatable results and will help users avoid methods and test conditions that have been shown to produce confusing or misleading data. The proposed standard will be used by ready-mixed concrete producers, suppliers of concrete-making materials, contractors, testing firms, researchers, and academia.
Doug Hooton, University of Toronto, and chair, Subcommittee C09.48, said that this new practice will help both suppliers of materials and concrete producers to pinpoint the source of fresh concrete problems in increasingly complex concrete mixtures and can be used to help prevent future problems as materials properties, mixture proportions, and placing temperatures change.