Liu Jun, Xu Zhishan, Ji Yongsheng
Department of Environmental Art Engineering, Nanjing Technical Vocational College, Nanjing 210037, China.
College of Wood Science and Technology, Nanjing Forestry University, Nanjing 210037, China.
Materials (Basel). 2024 Dec 28;18(1):89. doi: 10.3390/ma18010089.
The low hydration degree of fly ash in Fly Ash Unburned Lightweight Aggregate (FULA) is not conducive to the development of the mechanical properties of lightweight aggregates and their concrete. In this paper, FULA was immersed in an alkaline solution with the purpose of improving the mechanical properties of FULA and its concrete. Firstly, FULA was prepared using fly ash as the main raw material. The effect of the alkaline solution type and concentration on the basic properties of FULA was studied. Then, lightweight aggregate concrete was prepared using FULA as a coarse aggregate. The role of the aggregate category and water-cement ratio in the mechanical properties of concrete was analyzed. Finally, the effect of alkali curing on the interfacial transition zone of concrete was tested by combining an electron microscope and microhardness tester. Based on this, the strengthening mechanism of alkali curing on the mechanical properties of concrete was proposed. The results show that alkali curing can effectively improve the mechanical properties of FULA and its concrete. The microhardness of the interfacial transition zone of alkali curing FULA concrete is significantly higher than that of the cementite matrix, and the closer the aggregate, the higher the microhardness. The fundamental reason for this is that alkali curing improves the hydration degree of fly ash.
粉煤灰未燃尽轻集料（FULA）中粉煤灰的低水化程度不利于轻集料及其混凝土力学性能的发展。本文将FULA浸泡在碱性溶液中，旨在改善FULA及其混凝土的力学性能。首先，以粉煤灰为主要原料制备FULA。研究了碱性溶液类型和浓度对FULA基本性能的影响。然后，以FULA为粗集料制备轻集料混凝土。分析了集料类别和水灰比对混凝土力学性能的作用。最后，结合电子显微镜和显微硬度测试仪测试了碱养护对混凝土界面过渡区的影响。在此基础上，提出了碱养护对混凝土力学性能的增强机理。结果表明，碱养护能有效提高FULA及其混凝土的力学性能。碱养护FULA混凝土界面过渡区的显微硬度明显高于渗碳体基体，且距集料越近，显微硬度越高。其根本原因是碱养护提高了粉煤灰的水化程度。
