Specifications for asphalt

Asphalt specifications are designed to define an asphalt mixture with the capability to both perform for all required properties and not to fail in any of the potential failure mechanisms. Early asphalt specifications were based on attempts to replicate mixtures that had already proven themselves in practice. This approach implies specifying the same constituent materials that are mixed in the same proportions using the same procedures for mixing, transportation, laying and compaction under the same temperature and climatic conditions. This approach is generally called a recipe or recipe-type specification and puts all the responsibility for performance on the mixture designer/specifier provided the contractor has followed the specification precisely. This type of specification is referred to as ‘conventional’ in this book because they refer to a recipe for asphalt, an aspect of the recipe and/or a methodology for producing or laying the asphalt.