Applicability of LCA tool for building materials produced from construction and demolition waste : case of Tanzania

It is estimated that about 10 million tonnes of construction and demolition (C&D) waste is generated annually in Tanzania. This waste is expected to increase even more because of population increases, urbanization, industrialization and commercialization which results in more utilization of natural resources as well. The stock of material resources (raw materials) decrease worldwide and any excessive material extraction puts pressure on natural resources, including ecosystems which depend on this resource for survival. This justifies the research to find a proper technology for recovery (reusing, recycling and upcycling) of C&D wastes which would alleviate the excessive extraction and utilization of natural resources. The research aims at solutions to use the C&D waste to produce building materials (for example concrete blocks) which is a commonly used building material in Tanzania. To ensure the sustainability of such building materials, the environmental, social and economic parameters have to be assessed by using a Life Cycle Assessment (LCA) tool. Life cycle assessment is a technique for assessing the environmental impacts associated with a product over its life cycle. Currently, most of Life Cycle Assessment tools applied are developed in developed countries such as SimaPro (Netherlands), INVEST (United Kingdom), BEES (United States) etc. Their direct applicability is limited due to the fact that they are developed in countries with different environmental conditions as well as economic status. Therefore, this research paper discusses the identification of an appropriate Life Cycle Assessment tool which can be applied in research to determine the extent to which building products resulting from construction and demolition waste are sustainable in ecological sense

Innovative product through reusing and recycling of construction and demolition waste : case of Tanzania

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Use of recycled aggregates from construction and demolition waste for building construction in Dar es Salaam, Tanzania

Dar es Salaam city faces the shortage of building materials even though more than 50% of the builing materials produced are produced for Dar es Salaam market (Kimambo, 1988). In Tanzania, the major building materials used in building construction are building blocks. Concrete blocks are gaining importance in developing countries (Kaosol, 2010). According to the survey conducted in Dar es Salaam, it is estimated that about 70% of building materials is concrete and building blocks, whereby blocks occupy about 30% for high rise buildings and 70% for single storey buildings. The source of aggregate comes from quarry sites more than 120 km afar. Transportation of aggregates from far distant increases the cost of materials, energy consumption, traffic and environmental degradation. Since, Tanzania is one of the poor countries; it is very expensive to get building materials from far distance. Authors suggest that recycling of concrete rubble can be an alternative source of aggregates. In Tanzania, recycling of building material from construction and demolition rubble does not exist. About 20% of rubble is reused for backfilling of pothole, foundation and the rest is thrown away. The experience from developed countries shows that concrete rubble has great recycling potential; producing aggregates for stabilization of sub-base in road construction etc. These applications are lower applications (downcycling). The ongoing research project is investigating the possibility to recycle concrete rubble to generate load bearing concrete blocks for building construction. Keywords: Reuse, Recycling, C&D waste, building materials, concrete bloc

Concrete block production from construction and demolition waste in Tanzania

In Tanzania, construction and demolition (C&D) waste is not recycled and knowledge on how it can be recycled especially into valuable products like building materials are still limited. This study aimed at investigating the possibility of recycling the C&D waste (mainly cementitious rubble) into building material in Tanzania. The building materials produced from C&D waste was concrete blocks. The concrete blocks were required to have a load bearing capacity that meets the building material standards and specifications. Eight C&D waste samples were collected from C&D building sites, transported to the recycling site, crushed, and screened (sieved) to get the required recycled aggregates. Natural aggregates were also used as control. The recycled aggregates were tested in the laboratory following the standard methods as specified in Tanzanian standards. The physical, mechanical and chemical characteristics were determined. The physical and mechanical results showed that recycled aggregates were weaker than natural aggregates. However, chemically they were close to natural aggregates and therefore suitable for use in new concrete block production. In the production process, each experiment utilized 100% recycled aggregates for both fine and coarse portions to replace natural aggregates. The Fuller’s maximum density theory was used to determine the mix proportions of materials in which a method that specifies concrete mix by system of proportion or ratio was used. The concrete blocks production processes included batching, mixing (that was done manually to get homogeneous material), compacting and moulding by hand machine and curing in water. After 28 days of curing, the concrete blocks were tested in the laboratory on compressive strength, water absorption ratio and density. The results showed that the blocks produced with 100% recycled aggregates were weaker than those with natural aggregates. However, the results also showed that there is a possibility of recycling the C&D waste into building material because 85% of the tested concrete block specimens from recycled aggregates achieved a compressive strength of 7 N/mm2, which is defined as the minimum required load bearing capacity in Tanzania. Therefore, the C&D waste could be a potential resource for building material production for sustainable construction in Tanzania rather than discarding it. Further work should focus on the economic feasibility of production of concrete blocks with recycled aggregates in Tanzania

Investigation on the possibilities for recycling construction and demolition waste in to building materials in Tanzania

The scope of this study is to investigate the quality of C&D waste in Tanzania and the possibilities for reusing, recycling and upcycling this waste in the production of building materials. Even though there is currently no landfill for solid waste disposal in Tanzania, open air dumping sites are used. Dumping C&D waste puts pressure for acquisition for large portions of land in order to accommodate the growing waste generation. Due to population growth and limitation land for waste disposal will put extra pressure on C&D waste management in future. The use of C&D waste for building material production can be a best option not only for waste management but also for providing an alternative building material source. Materials used in this study were concrete/masonry rubble recovered from building construction and demolition sites in Dar es Salaam. Concrete/masonry rubble was crushed to produce aggregates. The results show that the recycled aggregates are mineralogically different from natural aggregates; however, their composition is suitable for use as building materials in Tanzania, e.g. as replacement of aggregates in concrete

Investigation on the possibilities for recycling construction and demolition waste in to building materials in Tanzania

The scope of this study is to investigate the quality of C&D waste in Tanzania and the possibilities for reusing, recycling and upcycling this waste in the production of building materials. Even though there is currently no landfill for solid waste disposal in Tanzania, open air dumping sites are used. Dumping C&D waste puts pressure for acquisition for large portions of land in order to accommodate the growing waste generation. Due to population growth and limitation land for waste disposal will put extra pressure on C&D waste management in future. The use of C&D waste for building material production can be a best option not only for waste management but also for providing an alternative building material source. Materials used in this study were concrete/masonry rubble recovered from building construction and demolition sites in Dar es Salaam. Concrete/masonry rubble was crushed to produce aggregates. The results show that the recycled aggregates are mineralogically different from natural aggregates; however, their composition is suitable for use as building materials in Tanzania, e.g. as replacement of aggregates in concrete