An evaluation of performance-related properties for granular pavement materials using a polyacrylamide additive

The use of polymeric-based additives for stabilising pavement materials has increased rapidly in recent years. Advantages typically include a reduction in permeability, an increase in durability, a non-time dependent mixing phase, and the provision of flexibility. Polyacrylamide (PAM) is one such additive that has demonstrated such advantages. However, little research has been conducted on measuring performance improvements for pavement materials. Thus, the aim of this study was to assess the benefits of using a synthetic PAM additive to improve various performance-related properties for three types of pavement materials commonly used in the construction of unsealed roads in Australia. The three materials selected for testing were a Silty Gravel, a Clayey Sand and a Clayey Gravel. The addition of PAM was found to increase the unconfined compressive strength and dry density for all soil types. Furthermore, the addition of PAM also changed the failure mode from brittle to ductile, which will naturally increase the fatigue life of the pavement. Improvement in tensile strength of the stabilised samples was also noted. Scanning Electron Microscopy analysis results revealed a decrease in the quantity of loose particles and pore volume, and an increase in contact points between particles for the treated samples, which further verified the mechanical and physical improvements gained by adding PAM to unbound pavement materials.