Hydration and rheological properties of municipal sludge co-processing cement

IF 6.5 2区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY
Jianyun Wang , Xianglong Ji , Depeng Chen , Chunxiang Qian , Gang Liu
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Abstract

The recycling and co-processing of municipal sludge in the production of cement clinker is a promising technology for the valorization of municipal solid wastes. However, the Al and Si rich in municipal sludge and the presence of heavy metals usually results in the different performance of municipal sludge co-processed cement (CPC) from normal ordinary Portland cement (OPC). To understand the variation in fresh behaviour, this study evaluated the flowability and rheological properties of CPC and OPC pastes with dosages of superplasticizers (SP). The hydration kinetics and hydration products of pastes in the fresh state were characterized. The influences of SP on the hardening properties of CPC and OPC samples were further addressed. The result indicated that the incorporation of SP provided a superior flowability of CPC pastes compared to OPC after mixing, however, the fast decline in flowability of CPC pastes in the first 40–80 minutes was confirmed. Consequently, CPC pastes presented faster development of static yield stress and dynamic yield stress compared to OPC with the SP dosage from 0.05 % to 0.125 %. CPC consumed significantly higher SP to achieve similar workability to OPC pastes. The characterization of reaction products indicated that hydration of CPC produced more ettringite and less portlandite in the first few minutes compared to OPC with or without SP. The application in OPC and CPC all reduced the volume of pores larger than 100 nm. The optimal SP could effectively promote the strength development of CPC and OPC at early ages.
城市污泥共处理水泥的水化和流变特性
水泥熟料生产中城市污泥的回收与协同处理是一种很有前途的城市生活垃圾资源化技术。然而,城市污泥中富含Al和Si以及重金属的存在往往导致城市污泥共处理水泥(CPC)的性能与普通硅酸盐水泥(OPC)不同。为了了解新鲜行为的变化,本研究评估了CPC和OPC浆料随高效减水剂(SP)用量的流动性和流变性能。对新鲜状态下膏体的水化动力学和水化产物进行了表征。进一步研究了SP对CPC和OPC试样硬化性能的影响。结果表明,SP的掺入使CPC膏体的流动性优于OPC,但在混合后的40-80 分钟内,CPC膏体的流动性迅速下降。结果表明,SP添加量在0.05 % ~ 0.125 %范围内,CPC膏体的静态屈服应力和动态屈服应力的发展速度均快于OPC。CPC消耗的SP明显更高,以达到与OPC膏体相似的和易性。反应产物表征表明,与添加或不添加SP的OPC相比,CPC水化前几分钟产生的钙矾石较多,波特兰石较少。OPC和CPC的应用均减少了大于100 nm的孔隙体积。最优SP能有效促进早期CPC和OPC的强度发展。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
7.60
自引率
19.40%
发文量
842
审稿时长
63 days
期刊介绍: Case Studies in Construction Materials provides a forum for the rapid publication of short, structured Case Studies on construction materials. In addition, the journal also publishes related Short Communications, Full length research article and Comprehensive review papers (by invitation). The journal will provide an essential compendium of case studies for practicing engineers, designers, researchers and other practitioners who are interested in all aspects construction materials. The journal will publish new and novel case studies, but will also provide a forum for the publication of high quality descriptions of classic construction material problems and solutions.
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