两类典型碱活性岩石在碱溶液中压蒸的反应产物

Autoclave Products of Two Kinds of Typical Alkali Reactive Rocks in Alkaline Solutions

用XRD和SEM/EDS研究了以加拿大Spratt硅质灰岩(SL岩石)和Pittsburg泥质白云质灰岩(PL岩石)为代表的两类典型碱活性岩石在1.8 mol/L KOH,NaOH和LiOH溶液中150℃压蒸150 h后的反应产物.结果表明:2种岩石在不同碱溶液中受侵蚀程度、压蒸产物种类、结晶程度、形貌及分布显著不同.PL岩石除发生去白云石化反应外,岩石中的隐晶质石英也与碱反应生成典型的碱-硅酸反应产物.SL岩石除隐晶质石英与碱反应外,岩石中少量的白云石晶体在碱溶液中可发生去白云石化反应;ASR和ACR可能在某些灰岩集料中同时发生,尽管ASR,ACR在不同岩石中的贡献可能存在差异.

Surface alteration of typical rocks with alkali-silica reactivity and alkali-carbonate reactivity, i.e. Spratt（SL） limestone and Pittsburg dolomitic（PL） limestone, were studied by XRD and SEM/EDS after autoclaved in 1.8 mol/L KOH, NaOH and LiOH solutions at 150 ℃ for 150 h. The results indicate that. （1）Both rocks suffer the strongest attack in NaOH solution and the weakest attack in LiOH solution. （2）For the products of both rocks autoclaved in different alkali media, the crystalline degree, morphology and distribution are quite different. Sheet-like tobermorite and poor crystalline or amorphous Na-Ca-Si gel products are mainly formed in NaOH solution. Well-formed crystalline products are formed on rock surfaces in KOH and LiOH solutions. （3）In addition to dedolomitization in PI. limestone in KOH, NaOH and LiOH solutions, cryptocrystalline quartz in the rock is also involved in reaction and forms typical alkali-silica product in NaOH and KOH solutions, but forms lithium silicate （Li2SiO3） in LiOH solution. （4）In addition to massive alkali-silica product formed in SL limestone autoclaved in different alkaline solutions, a small amount of dolomite existing in the limestone can also simultaneously dedolomitize in alkali solution. （5）ASR and ACR might coexist in some limestone aggregates, although the contributions from ASR and ACR might be different.