机场道面除冰液作用下大掺量粉煤灰混凝土的抗冻性

Freeze-thaw Durability of High Volume Fly Ash Content Concrete Exposed to Airfield Pavement Deicer

通过大掺量粉煤灰混凝土(HFCC)试件在质量分数为3.5%,12.5%,25%机场道面除冰液(CMA溶液)、质量分数为3.5%的NaCl溶液、质量分数为3.5%的飞机除冰液(AD溶液)、质量分数为25%的商品飞机除冰液与水中快速冻融试验,获得了冻融过程中HFCC的质量损失率和相对弹性模量的变化规律。结果表明:在质量分数为3.5%的介质中,HFCC在NaCl溶液中的冻融破坏以表面剥落为主,在AD,CMA溶液中以内部冻融损伤为主;与水中冻融条件相比,质量分数为3.5%的CMA溶液延缓了HFCC的冻融破坏作用;HFCC在CMA溶液作用下的冻融破坏与其质量分数密切相关,CMA溶液质量分数越高,HFCC的冻融破坏作用越小,当CMA溶液的质量分数在12.5%以上时,即使经受600次快速冻融循环,其质量损失率和相对动弹性模量损失均很小;在质量分数为25%的冻融介质中,HFCC在商品飞机除冰液中的抗冻性较差,在机场道面除冰液中抗冻性较好;HFCC完全能够应用于较高质量分数CMA溶液进行冬季除冰雪作业的水泥混凝土机场跑道。

The freeze-thaw durability of high volume fly ash content concrete （HFCC） specimens were tested by fast freezing-thawing experiments. In the experiments, HFCC specimens exposedto different solutions which were composed of airfield pavement deicer, NaC1 solution, aircraft deicer （AD）, commercial deicer and water. The airfield pavement deicer mainly contained calciummagnesium acetate （CMA） and was changed at mass fractions of 3.5%, 12.5% and 25%/00. The mass fractions of NaC1 solution, aircraft deicer and commercial deicer were 3. 5%, 3. 5% and25%, respectively. Through the experiments, the change rules of the mass loss rate per unit area and the relative dynamic elastic modulus of HFCC were obtained. The results show that freeze-thaw damage of HFCC exposed to 3. 5% NaC1 solution is closely attributed to surface deterioration. When HFCC specimens exposed to 3.5% AD or 3. 5% CMA solution, it will bedamaged by internal freeze-thaw damage. Compared with water, freeze-thaw damage effect of HFCC is delayed by 3.5% CMA solution. Freeze-thaw durability of concrete exposed to CMAsolutions is closely related to the solution mass fractions, the higher the CMA mass fraction is, the smaller the freeze-thaw damage effects are. When the CMA mass fraction is greater than 12.5%,the mass loss rate and the relative dynamic elastic modulus losses are small after 600 times fast freeze-thaw cycle. HFCC has a poor freeze-thaw durability when exposed to 25% commercialdeicer and has a good freeze-thaw durability when exposed to 25% airfield pavement deicer. Therefore, HFCC can be completely applied to the cement concrete airfield runway which isdeiced by high mass fractions of CMA.