低温条件下矿物掺合料对混凝土孔隙率的影响

Study on Porosity of Low-Temperature Concrete With Mineral Admixture

目的研究了在不掺防冻剂的情况下，掺合料种类及掺量对低温混凝土强度及孔隙率的影响．方法采用恒低温一次冻结法和自然变低温多次冻结法，测定混凝土在不同龄期的强度值。利用可蒸发水含量法测定对应龄期的孔隙率．结果当掺合料掺量相同时，自然变低温（-15～5℃）养护条件下混凝土抗压强度高于恒低温（-10℃）养护条件下混凝土抗压强度，孔隙率要低于恒低温（-10℃）养护条件下混凝土的孔隙率；当单掺粉煤灰时掺量低于15％、单掺硅灰时掺量低于8％，低温混凝土的密实性较好．结论对于混凝土冬季施工更合适采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．

Research about the effects of mineral admixture on the compressive strength and pore porosity of low-temperature concrete without antifreeze. With using once artificial freezing method and natural freezing method test the compressive strength of low-temperature concrete at different age and by testing the loss percentage of water（content of evaporative water）of saturated specimen test the pore porosity of low-temperature concrete at different age. The result shows that the compressive strength of concrete under natural variational low temperatural curing is higher than the compressive strength of concrete under permanent low temperatural curing and the pore porosity under natural variational low temperatural curing is less than the compressive strength of concrete under permanent low temperatural curing;the compactibility of concrete is good with FA（ 〈 15 % ） and SF（ 〈 8 % ）. The conclusion shows the method fits and the mineral admixture can reduce the pore porosity of con.crete and improve the compactibility and freezing resistance of concrete.