寒冷地区不同掺量Ⅱ类粉煤灰混凝土的力学特性研究

摘要

To explore cold region Ⅱ class fly ash concrete of different proportion of mechanical properties,this paper selected through orthogonal test the reasonable mixing ratio scheme,and independently developed the concrete curing test specimens box equipment is used for simulation of cold region freeze-thaw environment,analysis the water-binder ratio of 30％,under the condition of different dosage,curing time and the number of freeze-thaw circulation conditions Ⅱ class fly ash concrete workability,durability,and the strength of fly ash concrete mechanical characteristics are put forward.Research shows that: first,the mixed fly ash can significantly improve the workability of concrete,the late strength and frost resistance;Second,when 20％dosage of fly ash,specimen with moderate slump,compressive strength increased by 28.5％,frost resistance increased by 23％,the best mechanical properties index;At the same time,this paper found that the secondary hydration of fly ash and filling can effectively reduce the porosity of the concrete time,improve the frost resistance,if the content is more than 30％,the excess of fly ash particles can because of destruction of the rejection of concrete internal stability,indeed improve freeze-thaw deterioration rate.Hope that through this article research results and research and development equipment,degradation test equipment design for the environment,and the concrete performance of the cold north optimization applications provide certain reference.%为探究寒冷地区不同掺量Ⅱ类粉煤灰混凝土的力学特性,首先通过正交试验筛选出合理的配合比方案,并自主研制了混凝土试件养护试验箱设备用于模拟寒冷地区冻融环境,分析在水胶比为30％的工况下,不同掺量、养护时间和冻融循环次数条件时Ⅱ类粉煤灰混凝土的和易性、耐久性,并提出了粉煤灰混凝土的强度力学特性.研究表明:首先,粉煤灰的掺入能够显著提高混凝土的和易性、后期强度和抗冻性;其次,在粉煤灰掺量20％左右时,试件塌落度适中,抗压强度提高了28.5％,抗冻性提高了23％,力学特性指标达到最佳;同时,本文发现粉煤灰的二次水化和充填反映能够有效降低混凝土时间的孔隙率,提高其抗冻性,若掺量超过30％时,多余的粉煤灰颗粒会因排异破坏混凝土内部稳定性,反而提高冻融劣化速率.希望通过研究成果和研发设备,为环境劣化试验设备的设计以及北方寒冷地区混凝土性能的优化应用提供一定借鉴.