摘要
【目的】解析再生微粉焙烧活化机制,改善废弃混凝土的综合利用效果。【方法】分析焙烧条件对再生微粉火山灰反应活性的影响规律,结合综合热分析和X射线衍射技术对焙烧过程中再生微粉的物相变化进行分析讨论。【结果】再生微粉的活性指数随焙烧温度上升或焙烧时间延长而明显提高,但温度不宜高于600℃且时间控制在1.0~1.5 h,否则会导致再生微粉的活性指数下降;微观结构分析发现,温度为600℃、焙烧时间为1.5 h可使再生微粉中的高岭石等黏土矿物以及水化硅酸钙等水泥水化产物发生脱水分解,从而改善再生微粉的火山灰反应活性,但在更高的温度800~900℃下则形成铝硅尖晶石、钙黄长石等低活性物质,导致再生微粉火山灰反应活性下降。【结论】焙烧处理对再生微粉具有明显的活性激发作用,但焙烧温度和时间应与再生微粉的化学成分及矿物组成相匹配。
Objective Recycled fine powder(RFP)is microscaled granules generated in the preparation of recycled aggregates by a process of crushing of construction or demolition wastes.Some feasible ways have been developed to realize the resourced utilization of RFP,of which with the most adaptable one being as the active admixture for the production of Portland cement or commercial concrete.The higher the pozzolanic activity of RFP is,the greater the utilization rate that can be achieved.The process of calcination at a temperature not exceeding 1000℃is generally esteemed as one of the most effective ways to enhance the economic and technological results of RFP as concrete admixture.However,the activation mechanism of RFP in the process of high temperature calcination may not consistently explain the experimental results in any cases,since the the efficiency of calcination is apparently depending on the source of RFP material and the temperature regime of the calcination.A strong requirement arises subsequently to clarify the activization mechanism of RFP in the process of high temperature calcination.Methods In this paper,RFP specimens were calcined at a certain temperature ranging from 600 to 900℃,while the calcination time was adjusted in the range of 0.5 to 3.0 hours.The as-prepared RFP specimens were used to partly replace the Portland cement at a weight ratio of 30%for the preparation of standard mortar with a water-to-cement(W-C)ratio of 0.5 by weight and a weight ratio of 3∶1 for the standard sand to Portland cement.Changes in the compressive strength of such mortar blocks after the standard curing of 7 d and 28 d were investigated in details to reveal the effect of high temperature calcination on the pozzolanic activity of RFP,followed by the measurements and discussion of the microstructural characteristics of RFP by means of comprehensive thermal analysis,i.e.thermal gravity(TG)and differential scanning calorimeter(DSC),and X-ray diffraction(XRD)to demonstrate the phase changes of RFP during the high-temper
作者
刘燕妮
吴晓荣
王刚
赵明宇
佟钰
LIU Yanni;WU Xiaorong;WANG Gang;ZHAO Mingyu;TONG Yu(School of Materials Science and Engineering,Shenyang Jianzhu University,Shenyang 110168,China;The 2nd Construction Limited Company of China Construction Eighth Engineering Division,Jinan 250022,China)
出处
《中国粉体技术》
CAS
CSCD
2024年第5期113-120,共8页
China Powder Science and Technology
基金
国家自然科学基金项目,编号:52278266
辽宁省教育厅高等学校基本科研项目,编号:JYTZD2023165。
关键词
混凝土
再生微粉
焙烧
活性指数
微观结构
concrete
recycled fine powder
calcination
activity index
microstructural characteristics
