民用建筑用轻烧MgO膨胀剂的制备与性能

Preparation and Properties of Undercalcined MgO Expansive Agent(UMEA)for Civil Building

针对民用建筑混凝土收缩开裂的特点,以菱镁矿为原材料,制备了民用建筑用轻烧MgO膨胀剂(UMEA),研究了掺UMEA水泥净浆的变形性能,包括压蒸安定性能、水养(20℃)膨胀性能、自收缩性能以及干燥收缩性能.结果表明:UMEA既具有较大的早期膨胀、又具有持续的后期微膨胀,对水泥净浆自收缩和干燥收缩均具有较好的补偿作用;掺UMEA水泥净浆在压蒸条件(216℃,2.0 MPa)下表现出良好的体积稳定性,即使UMEA掺量为12%(质量分数)时水泥净浆的压蒸安定性仍然合格,因此UMEA作为民用建筑类膨胀剂具有广阔的发展前景.

In order to improve the volume stability of the concrete for civil building, the undercalcined MgO expansive agent（UMEA） was prepared at lower temperature with magnesite as raw material, and the properties of cement paste containing UMEA were investigated including autoclave soundness, expansion under water curing at 20℃, autogenous shrinkage and drying shrinkage. The results show that UMEA both has a large early expansion, also has the continuing micro-expansion at the late age, and can reduce the drying shrinkage as well as autogenous shrinkage of cement paste effectively. Cement paste containing UMEA has desired volume stability under autoclave condition（216℃ ,2.0 MPa） , the expansion of cement paste with 12% （by mass） UMEA is 0. 52% less than limited expansion of 0. 80%, so the maximum amount of MgO in cement paste can be extended to 12%. This is conducive to the application of UMEA in the concrete for civil building.