The conclusion shows the method fits and the mineral admixture can reduce the pore porosity of concrete and improve the compactibility and freezing resistance of concrete. 结论对于混凝土冬季施工更合适未用自然变低温养护的方法，掺入适量的掺合料能使混凝土孔隙率显著降低，使混凝土更加密实，提高混凝土的抗冻性。
These facts indicated that the development of freezing resistance of P. tomentosa cuttings induced by freezing acclimation required a certain temperature and duration. 反映了毛白杨幼苗抗冻性的诱导与发育需要一定的温度和锻炼时间。
