Abstract:
Disposing of demolished concrete wastes has substantial adverse effects for the
construction industry and as a whole for the natural environment. One of that is excess
loading on landfills which are not sufficient for other non-recyclable materials and the
other is not backing up of the natural aggregate which depletes through time due to the
flourishing construction activities in the country. Hence the aim of this work is to
investigate the effect of using demolished concrete waste as a coarse aggregate in hot mix
asphalt.
The research studied that the physical and geotechnical properties of demolished
concrete waste aggregate through intensive laboratory tests and laboratory tests were
conducted for hot mix asphalt prepared and tested by Marshall Mix design method with
incorporation of demolished concrete waste aggregate in proportions of (0%, 25%, 50%
& 75%).The volumetric properties of paving mixture investigated and optimum bitumen
contents were determined for the different percent compositions of demolished concrete
waste aggregate. Marshal flow & stability tests were conducted to know the performance
of paving mixture and performance test regarding moisture induced damage was
conducted in laboratory since the absorption of demolished concrete waste aggregate
was greater than that of natural crushed aggregate.
The test results shown that the physical property of demolished concrete waste aggregate
has lower specific gravity and higher water absorption than natural crushed aggregate
and it shows good resistance to Los Angeles Abrasion and static crushing load whereas
the aggregate crushing value is out of ERA specification. The volumetric properties (Air
void, voids in mineral aggregate), stability & bitumen contents increase as the percentage
composition of demolished concrete waste aggregate increase whereas 75% demolished
concrete waste aggregate replacement does not fulfill the ERA and MS-2 criteria of flow,
stability and voids filled with asphalt.
Hot mix asphalt incorporated with 25% & 50% demolished concrete waste aggregate
shows good performance against moisture induced damage. The test results have shown
that 25% up to 50% demolished concrete waste replacement can be utilized as coarse
aggregate in hot mix asphalt.
