Abstract
Cool road pavements contribute to mitigating urban heat islands. To evaluate the heat balance in paved surfaces and to select appropriate road construction materials that help suppress heat islands, an accurate understanding of heat transport parameters such as thermal conductivity (λ) and heat capacity (HC) is important. Recycled aggregates from construction and demolition waste, including scrap construction materials and industrial by-products, are often used for road construction; however, λ and HC of recycled aggregates especially for roadbeds are not fully understood. This study involved a series of laboratory tests to measure λ and HC of recycled concrete and clay brick aggregates (<40 mm) and their mixtures with autoclaved aerated concrete grains (<2 mm) under varied moisture conditions. The measured λ and HC increased with increasing volumetric water content (θ). Closed-form models for estimating λ(θ) were proposed using normalized thermal conductivity (λe) and effective saturation (Se). The new λe(Se) models performed well for the measured data compared to previously proposed models and would be useful to evaluate λ of recycled aggregates for roadbed materials.
Highlights
Natural resources have been always exploited in human activities, and the construction industry is one of the industries that uses the most natural resources [1]
The construction industry releases large amounts of solid waste into the environment during the processes of construction and demolition [1]. In developing countries such as those in Southeast Asia, along with economic development, the urbanization and industrialization has led to significant generation of construction and demolition waste (CDW), scrap construction materials (e.g., autoclaved aerated concrete (AAC)), and industrial by-products such as steel slag and coal ash [2,3]
The objectives of this study were, for recycled aggregates from concrete, clay brick, and their mixtures with autoclaved aerated concrete grains, that are often used as road base materials: (i) to evaluate the thermal conductivity and heat capacity under varied moisture conditions and (ii) to develop new models suitable for thermal conductivity of these materials
Summary
Natural resources have been always exploited in human activities, and the construction industry is one of the industries that uses the most natural resources [1]. The construction industry releases large amounts of solid waste into the environment during the processes of construction and demolition [1]. In developing countries such as those in Southeast Asia, along with economic development, the urbanization and industrialization has led to significant generation of construction and demolition waste (CDW), scrap construction materials (e.g., autoclaved aerated concrete (AAC)), and industrial by-products such as steel slag and coal ash [2,3]. While in the developed countries such as Japan, the USA, Australia, and members of the EU, most of the CDW, scrap construction materials, and industrial by-products are being recycled [4], in the developing countries, the percentage of recycled materials is very low. CDW is usually dumped at landfills without any treatment or illegally
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