Sulfate Resistance of Recycled Aggregate Concrete with GGBS and Fly Ash-Based Geopolymer

• Published in: Materials Vol. 12; no. 8; p. 1247
• Main Authors: Xie, Jianhe, Zhao, Jianbai, Wang, Junjie, Wang, Chonghao, Huang, Peiyan, Fang, Chi
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 16.04.2019; MDPI
• Subjects: Aggregates; Cement; Compression tests; Compressive strength; Concrete; Concrete aggregates; Concrete construction; Construction; Construction materials; Crack propagation; Demolition; Fly ash; geopolymer concrete; Geopolymers; GGBS; Granulation; ground granulated blast furnace slag; hydration mechanism; Mechanical properties; Natural resources; Physical properties; Raw materials; recycled aggregates; Recycled materials; Recycling; sulfate attack; Sulfate resistance; Waste disposal; fly ash; geopolymer concrete; ground granulated blast furnace slag; hydration mechanism; recycled aggregates; sulfate attack
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma12081247

There is a constant drive for the development of ultra-high-performance concrete using modern green engineering technologies. These concretes have to exhibit enhanced durability and incorporate energy-saving and environment-friendly functions. The object of this work was to develop a green concrete with an improved sulfate resistance. In this new type of concrete, recycled aggregates from construction and demolition (C&D) waste were used as coarse aggregates, and granulated blast furnace slag (GGBS) and fly ash-based geopolymer were used to totally replace the cement in concrete. This study focused on the sulfate resistance of this geopolymer recycled aggregate concrete (GRAC). A series of measurements including compression, X-ray diffraction (XRD), and scanning electron microscopy (SEM) tests were conducted to investigate the physical properties and hydration mechanisms of the GRAC after different exposure cycles in a sulfate environment. The results indicate that the GRAC with a higher content of GGBS had a lower mass loss and a higher residual compressive strength after the sulfate exposure. The proposed GRACs, showing an excellent sulfate resistance, can be used in construction projects in sulfate environments and hence can reduce the need for cement as well as the disposal of C&D wastes.