of natural mineral aggregates nomenclature for themore common or important natural minerals—an aid in determining their performance long as it takes to visually examine the sample minerals that makeup common aggregate sources. ASTM C 295, Petrographic examination of aggregates for concrete To outline petrographic examination procedures for aid indetermining their performance Visual and microscopic examination of prepared samples—sieve analysis, microscopy, scratch or acid tests examination does not involve long test periods Usually includes opticalmicroscopy. Also may include XRD analysis, differential thermal analysis, or infrared spectroscopy—see ASTM C 294 for descriptive nomenclature. ASTM C 342, Potential volume change of combinations To determine the potential ASR expansion of combinations Mortar bars stored in at 23°C (73.4°F) 52 weeks Primarily used for aggregates from Oklahoma, Kansas, Nebraska, and Iowa. ASTM C 441, Effectiveness of mineral admixtures or GBFS inpreventing excessive expansion of concrete due to alkali-silica reaction To determine effectiveness of supplementary cementing materials in controlling expansion from ASR Mortar Pyrex glass as over water at 37.8°C (100°F) and high relative humidity Varies: first measurement at 14 days, then 1, 2, 3, 4, 5, 9, and 12 months; every 6 months after that as necessary Highly reactive artificial aggregate may not represent real aggregate conditions. Pyrex contains alkalies. ASTM C 856, Petrographic examination of hardened concrete To outline petrographic examination procedures for hardened in determining Visual (unmagnified) and microscopic examination of prepared samples Short duration — includes preparation of samples and visual and Specimens can be examined with stereomicroscopes,polarizing microscopes, metallographic microscopes, and scanning electron microscope.
condition or performance microscope examination ASTM C 856 (AASHTO T 299), Annex uranyl- acetate treatment procedure To identify products of ASR in hardened concrete Staining of a freshly-exposed concrete surface and viewing under UV light Immediate results Identifies small amounts of ASR gel whether they cause expansion or not.Opal, a natural aggregate, and carbonated paste can results accordingly.Tests must be supplemented by petrographic examination and physical tests for determining concrete expansion Los Alamos staining method To identify products of ASR in hardened concrete. Staining of a surface with two different reagents. Immediate results ASTM C 1260 (AASHTO T303), Potential alkali reactivity of aggregates (mortar-bar method) To test the potential for deleterious alkali-silica reaction of aggregate in mortar bars Immersion of mortar bars in alkaline solution at 80°C (176°F) 16 days Very fast alternative to C 227. Useful for slowly reacting aggregates or those that produce expansion late in the reaction. ASTM C 1293, Determination of length change of concrete due to alkali-silica reaction (concrete test) To determine the potential ASR expansion of combinations. Concrete prisms stored over water at 38°C (100.4°F) Varies: first measurement at 7 days, then 28and 56 days, then 3,6,9,and 12 months; every 6 months as after that as necessary Preferred method of assessment. Best represents the field. Requires long test duration for meaningful results. Use as a supplement to C 227,C 295, C 289, and C 1260. Similar to CSA ASTM C 1567, Potential alkali-silica reactivity of combinations of cementitious materials and aggregate (accelerated To test the potential for deleterious alkali-silica reaction of cementitious materials and aggregate combinations in mortar bars Immersion of mortar bars in alkaline solution at 80°C (176°F) 16 days Very fast alternative to C 1293. Allows for evaluation of effectiveness of supplementary cementitious materials.