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 block