Reconstituted Cement Kiln Dust–Rice Husk Ash Stabilization of Reclaimed Asphalt Pavement as Highway Pavement Material

A large volume of cement kiln dust is generated as a solid waste by-product from the pre-heater by-pass systems during the manufacture of Portland cement clinker. It is disposed of on production sites, and sometimes in landfills. Pavement rehabilitation and reconstruction also generate a large volume of reclaimed asphalt pavement waste that is disposed of along road alignments, and rice husk ash is generated by the combustion of rice husk and disposed of as waste in large quantities in rice mills. This paper presents the results of a laboratory evaluation of the characteristics of reclaimed asphalt pavements stabilized using reconstituted cement kiln dust and rice husk ash waste with a view to determining its suitability for use as a flexible pavement material. The mixtures were subjected to British Standard light (standard Proctor) compactive efforts to determine the compaction characteristics and California bearing ratio. The test results show that the properties of reclaimed asphalt pavement waste improved with reconstituted cement kiln dust–rice husk ash waste treatment. The maximum dry density decreased and the optimum moisture content increased with increasing rice husk ash (RHA) content and decreasing cement kiln dust (CKD) and reclaimed asphalt pavement (RAP) contents in the mixes. Optimum California bearing ratio values of 34.0 % (unsoaked) and 54.0 % (soaked for 24 h) were recorded for 50 % RAP + 50 % (50 % CKD + 50 % RHA) mix. With the potential for time-dependent increases in strength in view, the optimum mixture satisfied durability requirements with insignificant water absorption and can be used as sub-base material in flexible pavement construction. This research provides results of the evaluation of RAP waste stabilized using reconstituted CKD and RHA wastes as highway construction material, as based on California bearing ratio determination. Further work is encouraged to assess the resilient modulus of this material under cyclic load.