Assessment of the Sub-Base Material for the Optimum Moisture Content and Maximum Dry Density Using Amalgamated Pond Ash with Reclaimed Asphalt on Road Pavement

Abstract

The subgrade is a crucial part of the pavement structure, as it transmits the load of vehicles on the pavement to the subsoil. The stability of the pavement depends on the stability characteristics of the subgrade. Roadwork waste materials (RWM) constitute a significant portion of waste materials used for roadway construction, particularly in base fill and backfill layers. Due to the shortage of virgin raw aggregates from quarries, alternative materials, such as RWM, are used as replacements in regular roadway construction. This research conducted a wide range of laboratory and field evaluations to determine the engineering properties of pond ash (PA) and reclaimed asphalt pavement (RAP), focusing on bottom ash as a blended material. Geotechnical parameters, such as particle size and mechanical properties of the materials, were assessed to evaluate their performance in pavement base or sub-base applications. The interaction of integrity between pond ash, RAP, and natural backfill as homogeneous materials was assessed by examining consistency characteristics concerning optimum moisture content (OMC) and maximum dry density (MDD). Six proportions of pond ash, RAP, and backfill soil (PA, RAP, NBS) were identified and used, with the optimal proportion being 50%:30%:20%. The grain size of RAP required for soil testing suitability will be obtained by disintegration using an earth hammering machine.