活性氧化镁对碱矿渣混凝土抗碳化性能影响研究

Study on the Effect of MgO on Carbornation Behavior of Alkail-activated Slag Concrete

研究了活性氧化镁对碱矿渣混凝土抗碳化性能的影响。研究了掺入氧化镁后浆体吸水率、混凝土干缩率、抗氯离子渗透性能,以及混凝土碳化深度的变化,并进一步分析掺入氧化镁后浆体水化产物和碳化产物的变化。结果显示,掺入氧化镁有助于降低浆体的吸水率、减少混凝土干缩和提高混凝土抗渗性。此外,氧化镁促进浆体中类水滑石的生成,碳化时延缓C-S-H凝胶的分解。最终导致混凝土碳化深度的降低。56d时,掺入3%氧化镁可以使碳化深度下降60%,而掺入6%氧化镁可使碳化深度下降80%以上。

The effect of active MgO on the carbonation resistance of alkali-activated slag concrete was studied. The performances such as paste water absorption, dry shrinkage, the resistance to chloride ion permeability concrete carbonation depth were tested. The changes of hydration and carboantion products were analyzed. The experimental results show that incorporation of MgO can significantly reduce paste water absorption, decrease the dry shrinkage, and improve the permability resistance of the concrete. At the same time, it also can increase the amount of hydrotalcite-like and delay the decomposition of C-S-H. At last, these factors resulted in the reduction of the depth of concrete carbonation. Mixed with 3% MgO can make carbonation depth reduce 60%, but 6% MgO added can make the carbonation depth decrease more than 80%.