ABSTRACT
Using waste concrete to prepare RAC could be traced back to World War II (Olorunsogo et al. 2002). And in 1976, a concrete road in Lyon County, Iowa State, USA, which had been used for 42 years, was demolished; and the waste concrete blocks were crushed to small particles and then used as recycled aggregates. A new 1.6 km (1 mile) long, 25.4 cm (10 in.) thick road was paved with the RAC produced with these recycled aggregates. From then on, RAC was rapidly and widely applied in road engineering (Salem 1996). At present time, about 80%, 75% and 65% of the waste concrete was recycled to produce RAC in Denmark, Netherlands and Japan, respectively (Tam et al. 2005). In other countries, such as, Britain, France, Germany, Canada and South Africa, the recycling technology of waste concrete for preparing RAC has also been successfully applied (Olorunsogo et al. 2002).
