Subgrade and Pavement Construction

Construction is the critical phase in which design is refined through careful execution, highlighting that subgrade engineering is more complex than planning due to the heterogeneous nature of soil and rock materials. This chapter outlines essential subgrade construction methods, including layered placement, vertical filling, and systematic compaction techniques adapted to different soil types, while establishing key quality standards such as degree of compaction and porosity for rock-filled embankments. In addition, it discusses excavation methods for soil and rock cuttings and introduces innovative approaches, including the use of lightweight materials such as fly ash and expanded polystyrene (EPS), to reduce settlement and ensure the long-term performance of highway pavements.