Application of percent within limits concepts on a balanced mix design of asphalt mixtures

Abstract

ABSTRACT Many agencies have incorporated rutting, and more recently cracking laboratory tests in the design process of asphalt mixtures with the objective to produce a balance between the stability and durability of the final product. Although this performance-engineered mixture design (PEMD), called here balanced mix design (BMD), offers compelling benefits, it raises a number of questions regarding its compatibility with construction practices. The objective of this work is to relate a BMD method with realistic binder content construction tolerances by applying concepts of a percent-within-limits (PWL) approach to field QC/QA, accounting for the variability of both the laboratory performance tests and construction. Four Arkansas mixes were evaluated using the Illinois flexibility index test (I-FIT) and the asphalt pavement analyzer (APA), for which binder content (Pb) and compaction level (%Gmm) were varied in the laboratory. Monte Carlo simulations were employed to generate binder content variability distributions based on BMD diagrams. New approaches for setting PWL lower and upper specification limits (LSL and USL respectively), as well as a criterion for defining the constructability of a BMD are proposed.