碳化对混凝土碱骨料反应的影响

Influence of carbonation on alkali- aggregate reaction in concrete

为了合理地评价混凝土碱骨料反应发生的碱含量,研究了碳化对水泥石中钠离子分布的影响,阐明碳化作用下混凝土碱骨料反应特征。研究结果表明:水泥石碳化之前截面的钠离子分布比较均匀,碳化作用下水泥石中钠离子从碳化区向非碳化区迁移和浓缩,钠离子在碳化区浓度减少,非碳化区浓度升高,碳化界面钠离子浓度最大,显著提高水泥石内未碳化区的钠离子浓度,降低碱骨料反应发生的初始碱含量限制标准,易发生碱骨料反应。

In order to reasonably evaluate alkali content generated in alkali-aggregation reaction in concrete, the influence of carbonation on sodium ion concentration distribution inside hardened cement paste was investigated; the alkali-aggregate reaction characteristics in concrete under carbonation were clarified. The results show that sodium chloride distribution is relatively uniform before carbonation; during carbonation process sodium ions in the carbonation area migrate to the non-carbonation area, sodium ion concentration decreases in the carbonation area and increases in the non-carbonation area, and reaches maximum peak value in the carbonation interface. Thus the carbonation increases the sodium ion concentration in non-carbonation area in the concrete and reduces the initial critical sodium ion concentration for alkali aggregate reaction in the concrete that accelerates the alkali aggregate reaction.