The traditional requirements for specifying tolerances for binder spray rates and the methods used for measuring the transverse distribution of a spray bar were developed for spraying either penetration bitumen, cutback bitumen or bitumen emulsions in the construction of chip seals. However, with the increased usage over the past 20 years of more viscous non-Newtonian bituminous binders that have been modified with either polymers or crumb rubber, these requirements and methods have become impractical to execute. This paper discusses the latest developments in specifying the binder distributor's performance requirements including, inter alia, the development of a standard test known as the bucket test to measure transverse distribution on-site. The paper also looks at steps that have been taken to move towards a self regulating scheme for certifying the performance of binder distributors in South Africa. (a) For the covering entry of this conference, please see ITRD abstract no. E217100.
Abstract