Investigation On The Partial Use Of Demolished Concrete Waste As Coarseaggregate In Hot Mix Asphalt

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.