再生砌体细集料砂浆抗冻性能研究

Study on frost resistance of recycled masonry fine aggregate mortar

为研究冻融条件下再生砌体细集料砂浆抗冻性能,采用再生砌体细集料、天然砂和粉煤灰制备3种再生砂砌体细集料砂浆。通过抗压强度试验研究冻融循环后试样的强度变化规律,通过SEM观察冻融循环后砂浆与骨料界面微观结构的变化情况。采用ABAQUS对试件进行冻融循环热力耦合分析,探索冻融循环对试件损伤的内在机理。研究表明:掺加天然砂、粉煤灰能够提高再生砌体细集料砂浆的抗冻性能,改善再生砂浆微观结构,抑制冻融过程中再生砌体细集料砂浆内部微观裂缝发展。在冻融过程中,试件内、外部温度梯度大,温度应力集中在立方体模型棱角处。

In order to study the frost resistance of recycled fine aggregate mortar for masonry under freezethaw conditions,three kinds of recycled fine aggregate mortar for masonry were prepared by using recycled fine aggregate for masonry,natural sand and fly ash.The compressive strength test is used to study the strength change rule of the sample after freeze-thaw cycle,and the change of the microstructure of the interface between mortar and aggregate after freeze-thaw cycle is observed by SEM.ABAQUS was used to analyze the thermal mechanical coupling of freeze-thaw cycles,and explore the inherent mechanism of damage caused by freezethaw cycles.The research shows that adding natural sand and fly ash can improve the frost resistance of recycled masonry fine aggregate mortar,improve the microstructure of recycled mortar,and inhibit the development of internal micro cracks of recycled masonry fine aggregate mortar during freezing and thawing.In the process of freezing and thawing,the temperature gradient inside and outside the specimen is large,and the temperature stress is concentrated at the corners of the cube model.