改性MgO膨胀剂对水泥浆体流动度和膨胀性能的影响

为了改善MgO膨胀剂(MgO expansive agent,简称MEA)对混凝土流动性的不利影响和延缓氧化镁混凝土的膨胀时间,采用十八碳不饱和脂肪酸对MEA进行表面改性,测试了改性MEA的活性指数、孔结构和水化热等特性,并通过测定掺改性MEA的水泥浆体的流动度和膨胀性能来评价其改性效果。结果表明:MEA经过表面改性后,其活性指数增大,孔结构被细化,水化放热时间有所延迟;改性MEA可明显降低MEA水泥浆体的流动度经时损失,并有效地延缓MEA水泥浆体的膨胀时间,提高其后期膨胀量。研究成果可为表面改性MEA在大体积混凝土中的应用提供参考。

Influence of Modified MgO Expansive Agent on the Fluidity and Expansion of Cement Pastes

To minimize the adverse impact of MgO expansive agent (MEA) on the fluidity of concrete and delay the expansion of MgO concrete, the surface of MEA was modified by adding C-18 unsaturated fatty acid. The activity index, pore structure and hydration heat of modified MEA were measured, and the fluidity and expansion of cement pastes containing modified MEA were investigated to evaluate the modification effect of MEA. Results demonstrated that the activity index of MEA can be improved, the pore structure of MEA can be refined and the hydration heat of MEA can be delayed by modifying MEA. The loss of fluidity of MEA cement pastes can be reduced, and the expansion of MEA cement pastes can be delayed and the later expansion quantity of MEA cement pastes can be increased by modifying MEA.