Recycling building materials

This strategy features in the framework of Agenda 21 as formulated at UNCED (Rio de Janeiro, 1992), now coordinated by the United Nations Commission on Sustainable Development and implemented through national and local authorities.

Agenda 21 recommends introduction of legislation and financial incentives to promote recycling of materials, particularly energy-intensive materials, in the construction industry, and the conservation of waste energy in building-materials production methods.

It is estimated that there is roughly 2,000 to 3,000 million tonnes of global building waste production per year. Very little of this waste is recycled, the majority being deposited or used as fill. With large reconstruction projects, required for instance as a result of war and natural disaster damage, the use of recycled materials in such situations can be very cost-effective. Most building and construction waste can be recycled and used in new structures, substituting raw materials. Masonry and damaged bricks can be crushed and used as gravel, or if of a good quality, used as aggregate in low grade concrete. Bricks of a high quality or undamaged can be cleaned and reused as new bricks. The wooded materials of building and construction waste is only partly recyclable, partly because of chemical leaching and contamination from pants and the like. Unpolluted wood can be shredded for other uses, and clean high-quality wood can be reused for new construction. Metal recycling is normal routine. Recycling possibilities for other types of building materials tend to be less. The Netherlands has a recycling goal of 90% for 2000.