TITLE:
Using Microwave Heating to Completely Recycle Concrete
AUTHORS:
Heesup Choi, Myungkwan Lim, Hyeonggil Choi, Ryoma Kitagaki, Takafumi Noguchi
KEYWORDS:
Recycling, Surface Modification, Interfacial Transition Zone, Pozzolanic Reaction, Microwave, Recovery
JOURNAL NAME:
Journal of Environmental Protection,
Vol.5 No.7,
May
28,
2014
ABSTRACT: The aim
of this study was to develop a technique for the complete recycling of concrete
based on microwave heating of surface modification coarse aggregate (SMCA) with
only inorganic materials such as cement and pozzolanic materials (silica fume,
fly ash). The mechanical properties of SMCA, which was produced using original
coarse aggregate (OCA) and inorganic admixtures, as well as its separation from
the cement matrix and recovery performance were quantitatively assessed. The
experimental results showed that micro structural reinforcement of the
interfacial transition zone, which is a weak part of concrete, by coating the
surface of the OCA with cement and admixtures such as pozzolanic materials can
help suppress the occurrence of micro-cracks and improve the mechanical
performance of the OCA. Microwave heating was observed to cause micro-cracking
and hydrate decomposition. Increasing the void volume and weakening the
hydrated cement paste led to the effective recovery of recycled coarse
aggregate.