Mechanical Properties and ITZ Microstructure of Recycled Aggregate Concrete Using Carbonated Recycled Coarse Aggregate
来源期刊:Journal Of Wuhan University Of Technology Materials Science Edition2018年第3期
论文作者:伍君勇 张云升 ZHU Pinghua FENG Jincai 胡坤
文章页码:648 - 653
摘 要:The effect of carbonation treatment and mixing method on the mechanical properties and interfacial transition zone(ITZ) properties of recycled aggregate concrete(RAC) was investigated. Properties of recycled concrete aggregate(RCA) were tested firstly. Then, five types of concretes were made and slump of fresh concrete was measured immediately after mixing. Compressive strength and splitting tensile strength of hardened concrete were measured at 28 d. Meanwhile, the microstructure of RAC was analyzed by backscattered electron(BSE) image. It was found that the water absorption ratio of carbonated recycled concrete aggregate(CRCA) was much lower when compared to the untreated RCA. Comparatively, the apparent density of CRCA was not significantly modified. The concrete strength results indicate that the mix CRAC-2 prepared with CRCA by adopting two-stage mixing approach shows the highest compressive strength value compared to the other mixes. The microstructural analysis demonstrate that the mix CRAC-2 has a much denser old ITZ than the untreated RAC because of the chemical reaction between CO2 and the hydration products of RCA. This study confirms that the ITZ microstructure of RAC can be efficiently modified by carbonation treatment of RCA and encourages broadening the application of construction and demolition wastes.
伍君勇1,2,3,张云升1,ZHU Pinghua2,FENG Jincai2,胡坤2
1. Jiangsu Key Laboratory of Construction Materials, School of Material Science and Engineering, Southeast University2. Department of Civil Engineering, Changzhou University3. Laboratory of Construction Materials,Swiss Federal Institute of Technology (EPFL)
摘 要:The effect of carbonation treatment and mixing method on the mechanical properties and interfacial transition zone(ITZ) properties of recycled aggregate concrete(RAC) was investigated. Properties of recycled concrete aggregate(RCA) were tested firstly. Then, five types of concretes were made and slump of fresh concrete was measured immediately after mixing. Compressive strength and splitting tensile strength of hardened concrete were measured at 28 d. Meanwhile, the microstructure of RAC was analyzed by backscattered electron(BSE) image. It was found that the water absorption ratio of carbonated recycled concrete aggregate(CRCA) was much lower when compared to the untreated RCA. Comparatively, the apparent density of CRCA was not significantly modified. The concrete strength results indicate that the mix CRAC-2 prepared with CRCA by adopting two-stage mixing approach shows the highest compressive strength value compared to the other mixes. The microstructural analysis demonstrate that the mix CRAC-2 has a much denser old ITZ than the untreated RAC because of the chemical reaction between CO2 and the hydration products of RCA. This study confirms that the ITZ microstructure of RAC can be efficiently modified by carbonation treatment of RCA and encourages broadening the application of construction and demolition wastes.
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