A material performance test for pavement foundations

The current pavement foundation process in the UK is base don the California Bearing Ratio, coupled with a method specification based on past experience and proven performance. This provides a trusted empirical indicator of adequate performance. The wider use of marginal and recycled / secondary aggregates is necessary for achieving industry sustainability targets. There is also a move towards analytical design, based upon the fundamental material performance properties of elastic stiffness and shear strength. Analytical design combined with performance based specifications, potentially allow any materials that are fit for purpose. This approach, however, requires field measurements to confirm the assumed design performance is achieved. In addition, performance data for analytical design are required, before the materials are used to ensure confidence in their likely behaviour and hence in the design. A large scale laboratory assessment test has been developed to measure the performance of coarse granular materials. The test utilises the same portable devices used to measure performance in the field, thus providing directly comparable results. This paper discusses the development of the laboratory performance test, its use and role in the wider context of the design process, and what advantages it brings to the highway construction industry. For the covering abstract see ITRD E145817