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Along with economic development, urbanization will generate a large amount of solid waste and put pressure on the waste management systems in developing countries. Face-to-face interview methods were used to investigate the current status of construction and demolition waste (CDW) management (collection, transportation, treatment, and storage) as well as reveal attitudes of governmental agencies and enterprises towards CDW recycling and recycled material products in Hai Phong City, Vietnam. Waste generation rates (WGRs) of the works were also determined by site surveys and as-built drawings method of typical old buildings to be demolished and two licensed new construction works. WGRs of 34.5 kg/m2 and 758 kg/m2 were identified during the construction and demolition of small private houses, respectively, while WGRs at public house demolition sites were 1053 kg/m2. To effectively manage the CDW, the gross floor area of new construction work was estimated by a multiple regression equation with the population and gross region domestic product growth. Based on this model combining the investigation results, the amount of CDW increase in 5–30 years is also predicted. This data set will help management agencies plan storage yards as well as select the appropriate CDW treatment and recycling methods, contributing to building a sustainable and effective CDW management model for Hai Phong City as well as Vietnam in the future. [ABSTRACT FROM AUTHOR]

Reuse and recycling of non-hazardous construction and demolition waste and industrial byproducts in the construction industry is vital to promote environmentally sound waste management. In particular, the effective utilization of sludge and waste clay bricks is greatly required in developing countries. This paper studied compaction characteristics and the California bearing ratio (CBR) of water treatment sludge (WTS) blended with clay brick aggregates for the road subgrade application. Raw and waste clay bricks from Vietnam were used for preparing clay brick (CB) and recycled clay brick (RCB) aggregates of three different particle sizes, Coarse 10- 30 mm, Graded 2-30 mm, and Fine 2-10 mm. In addition, fine residues of clay bricks with a size of < 2 mm were tested. WTS sieved under 2.0 mm blended with CB/RCB aggregates with different mixing proportions (f) were used for compaction and CBR tests in the laboratory. Results showed that the measured maximum dry densities (MDD) were dependent solely on mixing proportion f and increased linearly with f irrespective of blended fractions of CB/RCB aggregates. Unlike MDD, the measured CBR was dependent on both f and blended fractions. Especially, the WTS blended with coarse and graded fractions with a range of 60 ≤ f ≤ 80% showed a significant improvement in CBR (>100%). Due to its limited particle breakage and high CBR, the WTS blended with graded CB/RCB aggregates was preferable for the road subgrade application. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study collected basic information and conducted waste composition surveys to identify the present management condition of construction and demolition waste (CDW) landfills in Hanoi of Vietnam and to characterize waste composition and grain size distribution of CDW dumped at landfills. Basic information on seven CDW landfills under operation or closed/abandoned was collected, and the waste composition and the grain size distributions of dumped CDW at two landfills were investigated. Results showed that only one landfill site is currently under operation in Hanoi. Sanitary conditions of investigated landfills were relatively good without dumping of hazardous waste. Illegal dumping of domestic waste from residents, however, could be observed more or less at all sites due to an unclear boundary between dumping and surrounding areas. To improve current management of CDW landfills, a suitable recording system of accepted/dumped CDW and technical support for site managers are required as well as the implementation plan for developing and renovating landfills. Based on the results of the waste composition survey, the major components of dumped CDW were "Concrete", "Clay bricks", and "Soil-like", and the sum of these materials reached >80% of the total. Grain size distributions of "Concrete" ranged from 10–600 mm and of "Clay bricks" ranged from 10–300 mm. Technical recommendations to examine a potential availability of dumped "Concrete" and "Clay bricks" as a base material in road construction are summarized from the viewpoints of segregation from "Soil-like" and impurities, grading of "Concrete" and "Clay bricks", mechanical properties and environmental safety, and economic feasibility. The findings in this study raise challenges and perspectives to establish sound CDW management and to promote sustainable development of CDW recycling in Vietnam. [ABSTRACT FROM AUTHOR]