Reactivity of Quartz at Normal Temperatures: Fid-Bau Portal

Reactivity of Quartz at Normal Temperatures

A. D. Budk / K. Mather

This project involved a study of eight natural gravels composed largely of quartz and quartzite. It was shown that strained quartz can be a potentially deleteriously reactive constituent of concrete aggregate, and criteria were developed to recognize such material before its use as concrete aggregate. An aggregate should be regarded as potentially deleteriously reactive if it contains more than 20 percent strained quartz having an average undulatory extinction angle larger than 15 deg. Such an aggregate should then be tested in mortar bars stored at 60 C. If the aggregate is a fine aggregate, it should be used as the aggregate in making the mortar. If the aggregate is a coarse aggregate, five particles of suitable size should be embedded in the mortar bar. An expansion of 0.025 percent in 6 months or 0.040 percent in 12 months is confirmation of its potential reactivity and the need for control measures. These criteria were incorporated into Appendix B, 'Alkali-Silica Aggregate Reactions,' of the Corps of Engineers Standard Practice for Concrete for Civil Works (EM 1110-2-2000) by a change dated 25 March 1983. Originator - supplied keywords include: Alkali-aggregate reactions, Quartzite, and Aggregates (Building materials).