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. 結論對于混凝土冬季施工更合適未用自然變低溫養護的方法，摻入適量的摻合料能使混凝土孔隙率顯著(zhù)降低，使混凝土更加密實(shí)，提高混凝土的抗凍性。
These facts indicated that the development of freezing resistance of P. tomentosa cuttings induced by freezing acclimation required a certain temperature and duration. 反映了毛白楊幼苗抗凍性的誘導與發(fā)育需要一定的溫度和鍛煉時(shí)間。
