活性MgO?粉煤灰固化淤泥耐久性研究

将绿色环保活性MgO?粉煤灰材料引入淤泥固化，采用系列室内模拟试验，深入研究冻融、浸水和干湿等复杂气候环境下活性MgO?粉煤灰固化淤泥试样的外观形貌和强度特征，明确外界环境干扰诱使固化淤泥性能演化的内在规律。结果表明：活性MgO?粉煤灰固化淤泥具有良好的抗冻融、抗干湿及水稳性，且活性MgO?粉煤灰掺量及MgO/粉煤灰配比提高可进一步改善活性MgO?粉煤灰固化淤泥试样的耐久性能。冻融、浸水和干湿等复杂环境显著劣化固化淤泥抗压强度，其强度水平均低于同龄期标准养护试样。固化淤泥试样无侧限抗压强度随冻融循环次数增加而逐渐降低，随浸水时间增加先降低后趋于稳定，随干湿循环次数增加呈降低的趋势。基于所得试验结果，提出了活性MgO?粉煤灰固化淤泥耐久性演变的内在微观机制模型。

Study of durability of dredged sludge solidified with reactive MgO-fly ash

Based on series of laboratory tests including cyclic freeze-thaw, water immersion and cyclic drying-wetting, an experimental study has been performed to analyze the intrinsic change in the compressive strength and appearance of dredged sludge solidified with reactive MgO-fly ash, a green and environmental-friendly binder, and clarify the climate change-induced durability evolution. The test results indicate that the dredged sludge solidified with reactive MgO-fly ash has outstanding performance in resisting the damage from cyclic freeze-thaw, water immersion and cyclic drying-wetting. The durability performance of reactive MgO-fly ash solidified sludge is significantly enhanced as the MgO-fly ash content and mass ratio of MgO to fly ash increase. The strength behavior of MgO-fly ash solidified sludge is largely weakened by water immersion, cyclic dry-wet and cyclic freeze-thaw, and this causes a smaller compressive strength than that of samples cured under standard condition. As the number of freeze-thaw cycle increases, the compressive strength tends to decrease gradually. The compressive strength of samples immersed in water is initially reduced, and then changes within a limited interval. The compressive strength of damaged samples decreases with the increasing drying-wetting cycles. Based on the test results, an intrinsic microscopic mechanism model is proposed for the durability evolution of dredged sludge solidified with reactive MgO-fly ash.