Laboratory Evaluation of Crushed Concrete Aggregate as Unbounded Base and HMA Surface Course

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Addis Ababa University


To diminish the adverse effects of construction and demolition wastes, this research investigated the physical and geotechnical properties of crushed concrete aggregate through intensive laboratory tests to evaluate as using for base course of flexible pavement and also laboratory tests were conducted for hot mix asphalt prepared and tested by Marshall mix design method with incorporation of crushed concrete aggregate to natural crushed aggregate in proportions of (0, 30, 50 & 100%). The volumetric properties of paving mixture investigated and optimum bitumen contents were determined for the different percent compositions of aggregate. Marshal flow & stability tests were conducted to know the performance of paving mixture. Performance test regarding moisture induced damage was conducted in laboratory since the absorption of crushed concrete aggregate was greater than the natural aggregate. The physical property of crushed concrete aggregate indicates that CCA has lower specific gravity and higher absorption than natural crushed aggregate and it shows good resistance to Los Angeles Abrasion and static crushing load whereas the ten percent fines value reveals marginal quality. Voids (air void and voids in mineral aggregate), stability, flow & design bitumen contents increase as the percentage composition of CCA increase. Hot mix asphalt incorporated 30% & 50% CCA shows good performance against moisture induced damage. 100% CCA aggregate fulfill the requirements of base course (GB2 & GB3) as per ERA specifications. Finally a general method to evaluate the economics of utilizing crushed concrete aggregate is proposed.



Crushed Concrete Aggregate, Base Course, Hot Mix Asphalt, Indirect Tensile Strength, Optimum bitumen Content