The initial treatment of pavement surfaces by priming or primersealing is presenting an ever increasing challenge to sprayed sealing technologists. Increased traffic loading, shear stresses and degree of material compaction are all impacting on the performance of initial treatments and particularly primerseals. This paper examines some of these issues and explores the traditional design concepts and questions whether they are still appropriate or achievable. Primes present less of a challenge because they are not subject to trafficking. Appropriate testing followed by field trials and review of application rate and grade of primer has been observed to produce an effective prime. Primersealing is considered to be the greatest challenge. A requirement for maximum moisture content of the pavement at the time of primersealing should be implemented. Embedment, alignment, aggregate average least dimension and heavy vehicle percentage should all be considered as inputs to the design process. Further investigation work into the impact of varying cutter oil percentages in primer binders is recommended. Long and short term implications should be considered. Polymer modified emulsions have been used as initial seals on heavily trafficked pavements with some success. This type of technology may be the way forward. (a).
Abstract