A proposed ASTM International guide will help concrete professionals use mortar mixtures to compare the relative performance and compatibility of concrete materials.
     The guide standardizes procedures used for many years in material-performance investigations, according to ASTM International member Ara Jeknavorian of Jeknavorian Consulting Services.
     "This diagnostic tool will provide concrete technologists with useful defined mortar procedures to help anticipate an incompatibility of previously untested material combinations, or to troubleshoot unexpected concrete performance," he says, noting that the guide could help with material selection and quality control processes. Suppliers, producers, test labs, and government agencies can benefit from the tool, he adds.
     The guide (WK40615) is being developed by ASTM International's committee on concrete and concrete aggregates (C09).
     Jeknavorian says that technologists can use one of the guide's mortar tests to compare the relative workability, workability retention, set time, strength, and air content of two or more combinations of cement, sand, admixture, and fly ash. Test results could indicate that a change in material properties that could either favorably or unfavorably impact concrete performance. Results could also flag a potential material incompatibility that could become evident from poor concrete workability, a high air content, or delayed set times.
     "Should a discrepancy occur between parties on whether a particular material may be responsible for an unexpected concrete performance, the guide will enable two or more labs to conduct the same test procedures to help come to a consensus cause of the problem," he notes.
     For more information, contact Scott Orthey, sorthey@astm.org