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Construction and Demolition Waste as Recycled Aggregates in Alkali-Activated Concretes

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Civil and Environmental Engineering Department, University of Connecticut, 261 Glenbrook Road Unit 3037, Storrs, CT 06269-3037, USA
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Fibre and Particle Engineering, Faculty of Technology, University of Oulu, P.O. Box 4300, 90014 Oulu, Finland
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Department of Civil Engineering, California State University, Los Angeles, CA 90032, USA
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Author to whom correspondence should be addressed.
Materials 2019, 12(23), 4016; https://doi.org/10.3390/ma12234016
Received: 14 November 2019 / Revised: 27 November 2019 / Accepted: 29 November 2019 / Published: 3 December 2019
The growth of global construction has contributed to an inevitable increase in the amount of construction and demolition (C&D) waste, and the recycling of C&D waste as aggregates in concrete is receiving increased interest, resulting in less demand for normal aggregates and bringing a potential solution for the landfilling of wastes. Recently, several studies have focused on the use of C&D waste in alkali-activated concrete to move one step closer to sustainable concretes. This paper focuses on the main mechanisms of using C&D waste in the resulting physical, mechanical, and durability properties of alkali-activated concrete in fresh and hardened state properties. The main difficulties observed with recycled aggregates (RA) in concrete, such as high levels of water demand, porous structure, and low mechanical strength, occur in RA alkali-activated concretes. These are associated with the highly porous nature and defects of RA. However, the high calcium concentration of RA affects the binder gel products, accelerates the hardening rate of the concrete, and reduces the flowability of alkali-activated concretes. For this reason, several techniques have been investigated for modifying the water content and workability of the fresh matrix and for treating RA and RA/alkali-activated binder interactions to produce more sustainable alkali-activated concretes. View Full-Text
Keywords: alkali-activated concrete; recycled aggregate; construction and demolition waste; sustainability alkali-activated concrete; recycled aggregate; construction and demolition waste; sustainability
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MDPI and ACS Style

Abdollahnejad, Z.; Mastali, M.; Falah, M.; Luukkonen, T.; Mazari, M.; Illikainen, M. Construction and Demolition Waste as Recycled Aggregates in Alkali-Activated Concretes. Materials 2019, 12, 4016.

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