Volume 41, N. 2, May-August 2018 | DOWNLOAD PDF(21 downloads)
Abstract
The sustainable use of industrial wastes such as coal fly ash and carbide lime is an effective procedure to enhance the long-term performance of reclaimed asphalt pavement (RAP) under extreme freeze-thaw and wet-dry conditions. This study evaluates the impact of lime content (L) and dry unit weight (gd) on the durability and long-term performance of compacted RAP-fly ash-carbide lime mixes. For all mixtures tested, specimens were statically compacted inside a cylindrical mould to their target dry unit weights. Single-level variables used in the stabilisation process included: fly ash (FA) content of 25% (in relation to the RAP), optimum water content of 9% (modified compaction effort) and seven days of curing. Three target dry unit weights equal to 17, 18 and 19 kN/m3 (the last one determined using the modified Proctor energy) as well as three different lime contents (3, 5 and 7%) were also used in the analysis. Both the accumulated loss of mass (ALM) after wetting-drying and freezing-thawing cycles and the splitting tensile strength (qt) of the specimens tested were evaluated as a function of the porosity/lime ratio index (η/Liv). Compacted RAP-fly ash-carbide lime mixtures performed better when subjected to wetting-drying cycles than to freezing-thawing cycles. The results indicate that the porosity/lime ratio index controls not only the mechanical response but also the long-term performance of compacted RAP-fly ash-carbide lime mixes, which substantially broadens the applicability of the index.
