Geologist, Corps of Engineers, Vicksburg, MS
Some strained quartz may cause a deleterious alkali-silica reaction if present as a constituent of concrete aggregate in sufficient amounts. The criterion for reactive strained quartz is suggested to be more than 20% strained quartz with an average undulatory extinction angle greater than 15°. Length changes of mortar bars containing such strained quartz will be 0.025 and 0.040% or more at six and twelve months, respectively, when stored at a temperature of 60°C (140°F). Revisions to applicable ASTM standards may be appropriate.
Paper ID: CCA10264J