基于浆体替代法与水泥替代法的掺废弃混凝土粉水泥净浆性能试验研究

Experimental study of cement paste containing waste concrete dust based on paste and cement replacement methods

废弃混凝土粉(WCD)作为建筑垃圾的一种,会严重污染环境。WCD以往多以水泥替代的方式将其掺入水泥基材料中,但这样会导致力学性能的下降。浆体替代法是近年来提出的固废利用新方法,但该方法对WCD的研究仍是空白。以WCD为研究对象,对比采用浆体替代法与水泥替代法,对掺入WCD的净浆开展力学性试验与微观形貌分析。试验结果表明,在浆体替代法下,净浆所需的减水剂较多,但抗折和抗压强度均显著提升(最大增幅分别为17.5%和27.2%),且其微观结构更致密;而在水泥替代法下,净浆的减水剂剂量变化较小,但抗折、抗压强度随WCD掺量增加而明显降低(最大降幅分别为20.2%和20.6%),微观结构更为疏松。因此,相较于水泥替代法,浆体替代法可实现水泥基材料环保与性能的共同提升,值得更进一步探索。

As a kind of construction wastes,waste concrete dust(WCD)would seriously pollute the environment.Generally,WCD is reused as cement replacement in cement-based materials(CBMs),but such method may cause the reduction of mechanical properties of CBMs.In recent years,a new method,called paste replacement method,was proposed and applied to solid waste recycling,but little research was focused on WCD.In this study,both paste and cement replacement methods were applied,and mechanical tests and micro-structural analysis were carried out for the cement paste mixes containing WCD.The test results showed that,as paste replacement,WCD could demand more superplasticizer,but significantly improve the compressive and flexural strengths up to 17.5%and 27.2%,respectively,and densify the micro-structure.Whereas as cement replacement,WCD would have marginal effect on SP dosage,but reduce the compressive strength by 20.2%and flexural strength by 20.6%,and loosen the micro-structure.Therefore,compared to cement replace method,the paste replacement method,which can realize the coordination of environmental protection and performance improvement deserves further study.