Precast buildings can be disassembled and rebuilt for use in other locations, providing another way of extending the life of a building.
Durable, Adaptable, Demountable and Recyclable
Durability is a key component of a building's potential for reuse, but environmental implications are also involved. Buildings constructed from robust materials designed to withstand both occupant use and the elements for extended periods of time are often prime candidates for refurbishment and continued service. Buildings constructed from precast concrete meet both of these requirements. In fact, a building with a precast interior frame can have a life expectancy of hundreds of years.
Adaptability is a key factor underlying the ultimate service life of a building. If a structure is designed so that the interior of the building can be changed without major demolition, the building itself can have a long life and can be used for many purposes. Long spans, common in precast pre-stressed structures, are one way of promoting the adaptability of buildings. Increasing the load-carrying capacity of precast floor systems is inexpensive 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 easily installed or removed when occupancy requirements demand changes. Precast buildings can also be disassembled and rebuilt at another location, providing yet another means of extending service life. Precast floors and walls can also be disassembled from one structure and used on a different structure, providing that structure with the same benefits offered by new precast components.
At the end of a building's useful life, 100 percent of concrete demolition waste can be recycled. After reinforcement has been removed, concrete can be crushed to produce aggregate used in pavement construction, as granular sub-base, lean-concrete sub-base, and soil-cement aggregate. It can also been used on a limited scale as replacement aggregate in new concrete production.
Recycled concrete aggregate has a higher absorption rate and lower specific gravity than conventional aggregate, requiring stricter moisture control when stockpiled. Using recycled fine aggregate can result in a minor reduction of compressive strength; however, concrete made with recycled coarse aggregate and conventional fine aggregate can obtain adequate compressive strength. The drying shrinkage and creep is up to 100 percent higher than it is for concrete combined with corresponding amounts of conventional aggregate. For these reasons, large-scale use of recycled aggregate concrete has not been commonplace in Canada.