Groundnut Shell Ash Stabilized Reclaimed Asphalt Pavement, as Pavement Material

Abstract

Large volume of reclaimed asphalt pavements (RAP) aggregates are generated during pavement rehabilitation and reconstruction and disposed along road alignment while large quantities of groundnut shell ash (GSA) are generated from the combustion of groundnut shell and also disposed in large quantities on production sites. This paper presents results of the laboratory evaluation of the characteristics of GSA stabilized RAP with a view to determining its suitability for use as highway pavement material in flexible pavements construction. The RAP-GSA mixtures were subjected to British standard light (BSL) (standard Proctor) compactive effort to determine the compaction characteristics and California bearing ratio (CBR). Test results show that the properties of RAP improved with GSA treatment. The particle grading improved from 99.13% coarse aggregate and 0.87% fines, with AASHTO classification of A-1-b for 100% RAP and 9.08% coarse aggregate and 90.92% fines, with AASHTO classification of A-4 for 100% GSA to 15.6691.72% coarse aggregate and 8.2884.32% fines, with AASHTO classification in the range A-4 (silty soil) to A-1-a [granular material, for the various RAP-GSA mixes. Maximum dry density (MDD) decreased while the optimum moisture content (OMC) increased with higher GSA content in the RAP + GSA mixes. Optimum CBR values of 22.2% (unsoaked) and 18.3% (soaked) were recorded for 80% RAP + 20% GSA and 90% RAP + 10% GSA mixes, respectively. This optimum mixes satisfied durability requirement with insignificant water absorption and can be used as subgrade material in flexible pavements. This research provides the results to the evaluation of GSA stabilized RAP as highway construction material, as it is based on CBR determination. Further work may be encouraged to assess resilient modulus of this material under cyclic load.