A novel humidity regulating material hydrothermally synthetized from concrete waste
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ORIGINAL ARTICLE
A novel humidity regulating material hydrothermally synthetized from concrete waste Jiajun Miao1 · Zhenzi Jing1 · Hongyuan Fan1 · Haoran Lan1 · Deping Wang1 Received: 18 October 2019 / Accepted: 31 August 2020 © Springer Japan KK, part of Springer Nature 2020
Abstract To promote the recycling of construction wastes, a low temperature (≤ 200 ℃) hydrothermal technology for solidifying construction (concrete) waste into a tough and humidity self-regulating material has been developed, in which more than 60% of concrete waste could be recycled. During the process, the whole concrete waste including aggregates could be converted hydrothermally into tobermorite or C–S–H. The formed tobermorite could not only enhance the strength but also improve the porosity and thus enhance the humidity regulating capability. The maximum flexural strength reached up to 22 MPa, and the increased porosity could provide a good moisture adsorption/desorption performance (170 g/m2). With the addition of sepiolite, the performance could be further improved (250 g/m2) due to the coexistence of the formed tobermorite and remained sepiolite. The materials also exerted a remarkable damping effect on relative humidity (RH) variation indoors, e.g., the RH variation even could be decreased to 1/3 compared to that of empty reference (no humidity regulating materials were used). Graphic abstract
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10163-020-01110-6) contains supplementary material, which is available to authorized users. Extended author information available on the last page of the article
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Vol.:(0123456789)
Journal of Material Cycles and Waste Management
Keywords Concrete waste · Hydrothermal solidification · Tobermorite · Humidity regulating material
Introduction With the rapid urbanization in China, a lot of buildings are being built, and at the same time many old buildings which cannot meet new structural requirements and expectations are also being demolished. This suggests that a massive amount of building wastes are generated and meanwhile a huge amount of resources are still being used to produce building materials. For example, in China about 1 billion tons of construction wastes were generated [1], and meanwhile the only cement production was 2.4 billion tons in 2013 [2]. Obviously, the best way is to reuse construction wastes for building material manufacturing. The construction (concrete) wastes have been largely reused as recycled aggregates (RA) for years [3]. However, the defects of untreated RA, such as porosity, high sorptivity and chloride penetration etc., and also the low additional value of the other recycled products have restricted the recycling of concrete wastes dramatically [4–7]. It is well known that the main element composition of common cement (concrete) is Si, Al and Ca. Although the mineral composition of the cement will undergo some changes after hardening (for example calcium aluminum silicate formations), or even after de
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