ABSTRACT
This research examines effective crushing methods using a combination of various existing crushers for reinforced concrete structure waste from the demolition site of certain building erected several decades ago and have evaluated the recovered aggregate to see if it is effective as an aggregate for concrete from a grain size and quality standpoint.
Crushers used in the experiment included a jaw crusher for rough crushing, a hammer crusher for medium crushing, a roll crusher and an autogenous mill for crushing.
After crushing, recovered aggregate was found to be the same grain size as crushed stone aggregate after crushing with a jaw crusher. Furthermore, the grain size, grain distribution, specific gravity and coefficient of water absorption were improved by secondary crushing with a hammer crusher and autogenous mill, etc. This was due to the separation of cement paste attached to the surface of reused aggregate.
The quality of recovered/reused aggregate was found to be similar to the quality standard for crushed stone aggregate per JIS A 5005 “Crushed Stone for Concrete’’ and the quality of ordinary aggregate prescribed by “Reinforced Concrete Work JASS5” of the Architectural Institute of Japan.
