Study on products of alkali reactive aggregates autoclaved in different alkali solutions

Products of typical aggregates with alkali-silica reactivity, Spratt limestone (SL), and alkali-carbonate reactivity, Pitts-burg limestone (PL), after autoclaved in KOH. NaOH and LiOH solutions at 150°C for 150 h were studied by means of X-ray diffraction and scanning electron microscope/energy dispersive spectrometry. Results indicate that NaOH exhibits the strongest corrosive effect on both aggregates, while LiOH exhibits the weakest corrosive effect. The crystalline degree, morphology and distribution of products are quite different for both aggregates autoclaved in different alkali solutions. Except the dedolomitization of PL in alkali solutions, cryptocrystalline quartz in PL also react with NaOH, KOH to produce typical alkali-silica product and to form lithium silicate reacts with LiOH. Besides massive alkali-silica products formed in SL autoclaved in different alkali solutions, small amount of dolomite existed in SL are also dedolomitized in alkali solution, which is contributed to expansion.