菱镁矿尾渣煅烧MgO膨胀剂在一维限制砂浆中的膨胀性能

Expansion Characteristics of MgO-based Expansive Agents Produced by Magnesite Tailings in Restrained Mortars

为探讨菱镁矿尾渣在制备MgO膨胀剂(MEA)应用上的可能性,研究了辽宁海城菱镁矿尾渣煅烧MEA的活性及其在不同温度水养护砂浆试件中的一维限制膨胀率。结果表明,利用废弃菱镁矿尾渣经高温煅烧可制备出不同活性的混凝土用MEA,且煅烧温度越高,活性越低;不同养护温度下MEA表现出不同的膨胀性能,掺低活性MEA的砂浆试件的膨胀受养护温度的影响更为显著;相较于菱镁矿煅烧得到的MEA,由菱镁矿尾渣煅烧的MEA中有效方镁石成分较低,同掺量情况下膨胀性能较差,实际应用中可通过适当提高MEA掺量以保证对混凝土收缩的有效补偿。

In order to explore the probability of the application of MgO-based expansive agents （ MEA） produced by magnesite tailings, the activity of MEA and the one-dimension limited expansion of mortars mixed with MEA cured in water at different temperatures has been separately investigated. The results show that different activity MEA can be produced by magnesite tailings calcined at high temperature, and the higher the calcination temperature, the lower the activity. Different expansion characteristics is presented at different temperature water. Correspondingly, the increase of curing temperature exerts a significant impact on the mortars with lower activity MEA. Comparing with the MEA calcined by magnesite, the active components in the MEA calcined by magnesite tailing is relatively lower, as a result, the mortars with the same dosage of MEA perform a poor expansion characteristic. Therefore, in the practical application, the advisable dosage of MEA calcined by magnesite tailing should be properly raised, in order to effectively compensate the shrinkage of concrete.