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Load settlement behavior of reclaimed asphalt pavement (RAP) reinforced with polymer geogrid

Improvement of Reclaimed Asphalt Pavement (RAP) as generally obtained from milling / removal of bituminous layers of existing flexible pavement can be beneficially used as subbase / base course of new flexible pavement construction. Load settlement characteristics of untreated RAP in gen-eral are not very encouraging specially when placed over relatively weak subgrade. However, load set-tlement behavior of RAP can be substantially improved when the same is reinforced with commercially available polymer geogrid. In the present study, laboratory model tests have been conducted on RAP placed over soft marine clay bed having California bearing ratio value of 1.60 % with and without poly-mer geogrid reinforcement. Non woven geotextile has been used as a separator layer between soft marine clay bed and RAP layer. Biaxial geogrid having tensile strength of 80 kN/m have been used as reinforce-ment. Geogrid layer has been placed at different levels within the RAP layer to establish the most suitable location for placement of reinforcement to obtain maximum improvement in load settlement behavior. Based on model study it is observed that load carrying capacity of RAP for 50 mm settlement is increased to 1.26 times when RAP is reinforced by a layer of biaxial geogrid and the maximum improvement is ob-served when geogrid is placed near the top 1/3 depth of RAP layer.