公路路基工程用混凝土抗冻性能评价

Evaluation of Frost Resistance Performance of Concrete Used in Highway Subgrade Engineering

为了提高寒冷地区公路路基工程用混凝土的抗冻性能,以混凝土结构的质量损失率和相对动弹性模量为评价指标,重点考察了混凝土的水灰比、粉煤灰掺量以及引气剂掺量对其抗冻性能的影响。实验结果表明:混凝土的水灰比越大,其抗冻性能相对就越差;混凝土中粉煤灰的掺量越大,混凝土的抗冻性能相对越差;而混凝土中的引气剂掺量越大时,混凝土的抗冻性能相对越好。当混凝土的水灰比控制在0.35、未掺粉煤灰、引气剂的掺量为2 kg·m^(-3)时,混凝土试件经过100次冻融循环后的质量损失仅为0.12%,而相对动弹性模量则仍能达到70.5%,混凝土的抗冻能力较强。建议在寒冷地区公路路基工程的施工过程中,应尽可能地降低混凝土的水灰比,减少粉煤灰等掺合料的掺量,提高引气剂等外加剂的掺量,以最大限度地提高寒冷地区公路路基工程用混凝土结构的抗冻性能,延长其使用寿命。

In order to improve the frost resistance of concrete used in highway subgrade engineering in cold regions,the quality loss rate and relative dynamic modulus of elasticity of concrete structures were used as evaluation indicators,and the effects of water cement ratio,fly ash content,and air entraining agent content on the frost resistance of concrete were mainly investigated.The experimental results showed that the higher the water cement ratio of concrete,the poorer its frost resistance performance;the higher the content of fly ash in the concrete,the poorer the frost resistance of the concrete;the larger the amount of air entraining agent added to the concrete,the better its frost resistance.When the water cement ratio of concrete was controlled at 0.35,the fly ash was not added,and the dosage of air entraining agent was 2 kg·m^(-3),the mass loss of concrete specimens after 100 freeze-thaw cycles was only 0.12%,while the relative dynamic elastic modulus can still reached 70.5%,indicating strong frost resistance of concrete.It was recommended to reduce the water cement ratio of concrete as much as possible,minimize the dosage of fly ash and other admixtures,and increase the dosage of air entraining agents and other admixtures in the construction process of highway subgrade engineering in cold regions,in order to maximize the frost resistance of concrete structures used in highway subgrade engineering in cold regions and extend their service life.