全组分再生砂制备湿拌抹灰砂浆的抗冻性研究

Frost Resistance of Wet-Mixed Plastering Mortar Prepared by Full-Component Recycled Sand

目的研究全组分再生砂制备再生湿拌抹灰砂浆的抗冻性能,解决低温环境下的应用问题。方法分别以全组分再生砂、机制砂作为细骨料;粉煤灰、再生砖粉作为矿物掺合料;以质量损失率(Δm_(m))、强度损失率(Δf_(m))为冻融损伤指标,分析了25次冻融循环后不同配合比湿拌抹灰砂浆的抗冻性能。结果砂浆稠度分别与Δm_(m)、Δf_(m)有良好的线性关系。骨料与掺合料种类不变时,再生湿拌抹灰砂浆试件的胶砂比越小,其冻融破坏越严重。相同细度的再生砖粉需水量比和烧失量比粉煤灰小,火山灰活性更优,对抗冻性能的提升效果优于粉煤灰。全组分再生砂与机制砂相比吸水率较高,胶砂比及掺合料种类相同时,随着稠度值变大,全组分再生砂浆Δm_(m)、Δf_(m)值的增长率高于机制砂浆。再生湿拌抹灰砂浆的胶砂比不宜小于1/7。结论再生砖粉对于砂浆抗冻性能的提升作用优于粉煤灰,与全组分再生砂结合使用可以大大缩小与机制砂浆抗冻性能差距,可同时满足工程需要和固废再利用的目标。

Frost resistance of recycled wet-mixed plastering mortar prepared by full-component recycled sand is studied to provide reference for its application in low temperature areas.The frost resistance of wet-mixed plastering mortar with different mix ratios after 25 freeze-thaw cycles was studied by using full-component recycled sand and mechanism sand as fine aggregate,fly ash and recycled brick powder as mineral admixture,mass loss rate(Δm_(m)) and strength loss rate(Δf _(m))as indicators of freeze-thaw damage.Experimental results are that mortar consistency has a good linear relationship withΔm_(m),Δf _(m).When the type of aggregate and admixture is constant,the smaller the cement sand ratio of the specimen,the more serious the freeze-thaw damage is.The ratio of water dosage and ignition loss of the recycled brick powder are smaller than those of fly ash when they have the same fineness.Recycled brick powder has better pozzolanic activity and it’s improvement on frost resistance of mortar is better than that of fly ash.The full-component recycled sand has higher water absorption than that of the mechanism sand.When the cement sand ratio and admixture are the same,as consistency increases,the growth rate of theΔm_(m)andΔf _(m) of the all-component recycled mortar are higher than that of the mechanism_(m)ortar.The cement sand ratio of recycled wet-mixed plastering mortar should not be less than 1/7.The effect of recycled brick powder on frost resistance of mortar is better than fly ash.The gap of frost resistance between recycled wet-mixed plastering mortar and mechanism_(m)ortar can be greatly reduced by combining of recycled brick powder and whole component recycled sand.It can also meet engineering needs and solid waste reuse objective.