含碱矿物碱性环境下分解的热力学分析

应用热力学方法探讨了298K时钾长石、钠长石、霞石等含碱矿物在碱性环境下的碱析出能力,并对这些含碱矿物分解析出的碱对碱-硅酸反应的影响进行了讨论.结果表明:在pH值大于13的碱性环境下,各含碱矿物最大析碱能力顺序依次为:片铝钠石＞白榴石＞霞石＞脱水方沸石＞钠云母＞白云母＞硬玉＞钠长石＞钾长石;随着溶液pH值增大,片钠铝石、霞石分解能力略有降低,而集料中常见的钠长石、钾长石矿物的分解析碱能力则显著提高.此外,根据热力学分析结果,提出降低孔溶液碱度、采用低的水灰比以及控制外部水分进入孔溶液是抑制集料碱析出的有效措施,研究结果为相应的碱-集料反应抑制措施的提出提供了理论依据.

THERMODYNAMIC ANALYSIS OF ALKALINE MINERAL DISSOLUTION IN ALKALI SOLUTION

The dissolution reactions of alkaline minerals in alkali solution were studied by the thermodynamic method, and the capacities of alkali released from alkaline minerals and their effect on alkalisilica reactions (ASR) were analyzed also. The results indicate that the sequence of capacity in alkali released from alkaline minerals is dawsonite>leucite>nepheline>dehydration analcime>paragonite>muscovite>jadeite>Nafeldspar>Kfeldspar in alkali solution with a pH value higher than 13. With the increase of OH-concentration in alkali solution, the dissolution degree of the common minerals in aggregates such as Nafeldspar and Kfeldspar are increased remarkably, but the dissolution degree of dawsonite and nepheline are decreased slightly. Furthermore, it is pointed out that decreasing the pH value of the pore solution and preventing water from entering into the pore solution may be suitable way to restrain alkali from being released from the aggregate. The theoretical principle is introduced for inhibiting ASR according to the thermodynamic analysis.