Method to evaluate the reactivity of microcrystalline quartz in carbonate rock

In order to quantify the alkali reactivity of microcrystalline quartz in carbonate rocks, the profile-fitting technique was adopted to analyse its X ray diffraction lines of 20 = 66·5-70° using the FWHM (full width at half maximum) to monitor its crystallinity. It was found that for all the alkali-reactive carbonate rocks tested, silica was present as well-crystallized quartz. so expansion is not due to the alkali-silica reaction (ASR). This evidence supports the suggestion that expansion is caused by reaction between alkali and dolomite, rather than with silica. It is noted that the X ray diffraction method is a powerful means to investigate the reactivity of quartz.