Silica is generally found in water supplies in three different forms: reactive, colloidal and suspended particles (e.g., sand), with the reactive being that portion of the total dissolved silica that is readily reacted in the standard molybdate colorimetric test, and the colloidal being that which is not. • ASTM C 1293 — Testing period is lengthy and can result in leaching; test is unsuitable The reaction can presently be divided in two types: Alkali-Silica Reaction (ASR) and Alkali-Carbonate Reaction (ACR). • Petrography — Tool is useful but depends on skill of petrographer. The reactivity of a rock depends on the type and quantity of reactive minerals present, if any. Keeping this in view, trial was done for accelerated method of test. 4. Test methods are discussed in Section 7.6. ASTM C1293, Standard Test Method for Determination of Length Change of Concrete Due to Alkali-Silica Reaction. • ASTM C 227 — Test can result in leaching. C 1260 Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method) C 1293 Test Method for Concrete Aggregates by Determination of Length Change of Concrete Due to Alkali-Silica Reaction . SILICA, CRYSTALLINE, by XRD: METHOD 7500, Issue 4, dated 1 5 March 2003 - Page 3 of 9 NIOSH Manual of Analytical Methods (NMAM), Fourth Edition SPECIAL PRECAUTIONS: Avoi d inha li ng silic a d us t [3] . D 1193 Specification for Reagent Water This test method is the most reliable for determining the reactivity of aggregates, although it requires one year to complete. However, appropriate performance testing of specific aggregate sources is recommended to confirm alkali-silica reactivity. reactive silica by this test method provides a close approximation of total silica, and, in practice, the colorimetric method is frequently substituted for other more time-consuming techniques. Many consider ASTM C1293, Standard Test Method for Determination of Length Change of Concrete Due to Alkali-Silica Reaction(also known as the concrete prism test or CPT), to be the best test method … 2 -Pro pan ol, parlo dion and isope ntyl ace tate are flamm able. The presence of reactive minerals can usually be detected by a trained petrographer. The accelerated method of testing is still in experimental stage. as reactive when it is not) and false negatives (classifying reactive aggregates as innocuous). • ASTM C 289 — Test has poor reliability. T HF is extr emely f lamm able a nd shoul d be used in a fum e ho od. • ASTM C 1260 — Test can be overly severe. L. Gress University of New Hampshire September 2008 The undesirable expansion of concrete due to a reaction between alkalis in the cement and reactive siliceous aggregates, known as alkali-silica reactivity (ASR), RAPID TEST METHOD FOR DETERMINING ALKALI-SILICA REACTIVITY EXPANSION IN CONCRETE AND AGGREGATE BY Douglas R. Pac Thesis Director: David. expansions greater than 0.10 percent are indicative of potentially deleterious expansion. Worldwide, the occurrence of ASR is much more common that the occurrence of ACR. C 1437 Test Method for Determining Flow of Hydraulic Cement Mortar . A construction site cannot waif for so long period. 2.2 Alkali-reactive aggregates Alkali-reactive aggregates are aggregates that have been shown to react with alkali hydroxide and/or calcium Irrespective of which method is used and time permitting, the potential for deleterious expansion should be confirmed using ASTM C1293, “Standard Test Method for Determination of Length Change of Concrete Due to Alkali Silica Reaction.” Conventional method of test for alkali-silica reaction is very time consuming, as it requires a time of 6 months or more. — Tool is useful but depends on skill of petrographer skill of petrographer this in view, trial done. 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