Buildings constructed from robust materials that withstand the elements and occupant use for a very long time, are often prime candidates for refurbishment and continued service. Buildings constructed from precast concrete fit these criteria. A precast interior frame of a building can have a life expectancy of hundreds of years.
Adaptability is a key factor underlying the ultimate service life of a building. If a building is designed so that the interior of the building can be changed without major demolition, the building can have a long life. Long spans, common in precast prestressed structures, are one way of assisting the adaptability of buildings. Increasing the load carrying capacity of precast floor systems is not expensive and can extend the useful life of a building by providing flexibility for future conversion to other uses. Secondary installations, such as precast concrete mezzanine floors in industrial buildings, can be installed, or removed, when occupancy requirements change.
Precast buildings can also be disassembled and rebuilt at other locations, providing another means of extending service life.
At the end of a building’s useful life, 100% of concrete demolition waste can be recycled. After removal of the reinforcement, concrete can be crushed to produce aggregates that are primarily used in pavement construction, as granular sub-base, lean-concrete sub-base, and soil-cement aggregates. Recycled concrete has also been used on a limited scale as replacement aggregates in new concrete production.
Recycled concrete aggregates have a higher absorption and lower specific gravity than conventional aggregates. Concrete made with recycled coarse aggregates and conventional fine aggregates can obtain adequate compressive strength. The use of recycled fine aggregates can result in minor reduction of compressive strength. The drying shrinkage and creep is up to 100% higher than concrete with corresponding amounts of conventional aggregates. For these reasons, large scale use of recycled aggregate concrete has not yet been achieved in Canada.
