A byproduct of changes in bitumen quality is the trend for engineers to formulate asphalt mixes using a balanced mix design approach. This relatively new method accounts for variable bitumen specifications while prioritizing adherence to performance standards. Balanced mix design also allowed for incorporation of additives that can enhance the functional properties of a mix to improve performance outcomes. Rather than relying solely on binder or aggregate specifications to meet performance standards, all aspects of the mix (binder, aggregate, modifiers, and additives) are formulated to balance factors such as fatigue, rutting, and cracking characteristics.
How to use RAP
Everyone knows the value of RAP. But what is the best way to use it? Conventional wisdom suggests (AASHTO M 23) that one can use up to 15% RAP without changing the asphalt grade specified. When you want to use 15-25% RAP, it is suggested that you use one grade softer asphalt for your mix and when you use [...]
