中文摘要：

分析了混凝土在高温下和高温后两阶段中性化过程的机理，并通过试验研究了经历两阶段中性化过程后中性化深度的变化规律。研究结果表明：混凝土在高温下和高温后两阶段中性化过程中的中性化机理不同，前者对后者有一定影响；经历两阶段中性化过程后，随混凝土强度增加中性化深度减小幅度不断降低；随温度升高，中性化深度不断提高，但经历800℃高温后混凝土再碱化程度较高，对混凝土碳化具有一定的抵抗作用；高温后混凝土微观结构变化明显，能够反映出混凝土的中性化特征。

英文摘要：

Neutralization mechanisms on the two-stage neutralization process at high temperature and after high temperature were analyzed, and neutralization depth change regularities after the two-stage neutralization process were tested. Study results indicated： concrete neutralization mechanism at high temperature was different from that after high temperature, and the former had some effect on the latter. After the two-stage neutralization process, with concrete strength increased, the reduced amplitude of the neutralization depth was decreased. With the temperature elevated, the neutralization depth was increased, but concrete realkalisation after 800℃ could be enhanced, which would resist the carbonation to some extent. The micro-structure of concrete had obvious change after high temperature, by which the concrete neutralization features could be reflected.