英国伦敦大学学院Dr. Yun Bai学术讲座

The Potential of Microwave Curing for Manufacturing Low-carbon Concrete

主讲人 : Dr. Yun Bai

Steam curing is widely adopted by construction industry to facilitate the development of early strength of concrete. Although it can shorten the curing duration and provide economic benefits, it may lead to thermal stress inside the large or thick concrete products due to non-uniform heating. Moreover, it is not environmentally friendly due to its high energy consumption.

Different from steam curing which is dependent on thermal conduction, microwave heating relies on energy conversion, which can result in fast volumetric heating. All the components of concrete are dielectric materials, particularly water. They can absorb microwave effectively and electromagnetic energy can thus be converted into thermal energy. Hence, attempts have been made to apply microwave curing in the manufacture of cement and concrete products since 1980s. Although some pilot studies have proved that microwave curing could be a promising alternative accelerated curing method for the production of precast concrete with shorter curing duration and lower energy consumption, neither curing temperature nor relative humidity was well controlled during microwave curing process in these previous work, which may cause long-term strength loss and durability issues.

In this presentation, ongoing research on developing an intelligent microwave system for manufacturing concrete products is introduced. The key features of this microwave system include using optical fibre Bragg grating (FBG) sensors to control the temperature and the humidity inside concrete and microwave oven cavity, respectively. Using this tailored-made microwave system, research is ongoing in the Advanced and Innovative Materials (AIM) Group at University College London to explore the potential of curing two types of low-carbon cementitious systems, namely high-volume fly ash (HVFA) and alkali-activated fly ash (AAFA). In both systems, thermal curing is essential for the strength development, in particular, early strength development. The results indicated that even with 55% of Portland cement (PC) replaced by fly ash, the compressive strength of HVFA concrete can achieve 20MPa after only 8-hour’s microwave curing. In the case of AAFA system where 100% fly ash is activated by NaOH without using PC, a 42MPa compressive strength can be reached within 6 hours’ microwave curing, which compared to the 41 MPa compressive strength achieved after 24 hours’ thermal oven curing at 85oC, representing an 18-hour reduction of curing duration and 73% saving of energy consumption. d on the results obtained so far, the potential of this innovative microwave curing technique for future precast concrete manufacture is then discussed.

---

主讲人简介：

Dr. Yun Bai，（Reader in Materials），任职于英国伦敦大学学院（University College London， UCL）土木，环境与测绘工程学院（Department of Civil, Environmental & Geomatic Engineering, CEGE），土木工程系副主任，同时身兼CEGE土工与材料学部‘先进与创新材料课题组（Advanced & Innovative Materials (AIM) group）’负责人。

在具有超过600万英镑研究资金资助与一个拥有10名博士生、1名博士后研究员与2名技术管理员的团队合作下，Dr. Yun Bai 在目前所就职的UCL成功打造了AIM研究中心 - 此中心致力于推进以工业为导向、多学科的材料科学与工程研究，旨在为如今变化多端的社会与环境下工程师所面临的挑战提供最前沿的技术解决方案。本中心目前的研究课题包括：新型低碳&低能耗水泥基材料；先进复合材料；新型水泥&混凝土的流变学研究；混凝土结构的耐久性；结构健康监测；核废料固化等。

目前，Dr. Yun Bai受聘担任如下国际著名协会会员：国际建筑材料及结构试验与研究实验所联合会（RILEM） TC 224-AAM理事会；英国混凝土技术学会（The Institute of Concrete Technology，ICT）；英国混凝土技术学会的市场与事务理事会(The Events and Marketing Committee of The Institute of Concrete Technology)；英国材料、矿物及采矿学会的水泥基材料理事会(The Cementitious Materials Group Committee of The Institute of Materials, Minerals and Mining, IOM3)。