ABSTRACT
This chapter describes the laboratory investigation of ballast response under monotonic, cyclic, and impact loadings, using state-of-the-art large-scale cylindrical, prismoidal triaxial, and drop-weight impact equipment. To enhance the engineering performance of recycled ballast in track, an attempt was made to stabilise recycled ballast in the laboratory model using various types of geosynthetics. Three types of geosynthetics were used to stabilise recycled ballast in the laboratory model. These included: geogrid, woven geotextile, and geocomposite, a combination of geogrid and non-woven geotextile bonded together. The chapter describes physical, structural, and geotechnical characteristics of these geosynthetics. Two types of impact testing apparatus have been prevalent in practice for more than two decades, viz. drop-weight hammer and pendulum machine. The device used for measuring the transient impact loads is the dynamic load cell. The impact load is the contact force between the impactor and the test specimen as the drop-weight hammer strikes the shaft.
