5.1 Mix Design - Introduction

1 Introduction

The two key components of pavement design are mix design and structural design. This section deals with HMA and PCC mix design. The goal of mix design is to determine the optimum mixture of component materials for a given application. This includes detailed evaluations of aggregate, asphalt and portland cement as well as a determination of their optimum blending ratios. This section covers the following for HMA and PCC mix design:

Mix design fundamentals. These are the fundamental philosophies and parameters of mix design such as (1) why it is done, (2) what basic assumptions are made and (3) the specific goals of mix design.
Mix design methods. These sections cover the various mix design procedures used. For HMA, the Hveem, Marshall and Superpave methods are covered. For PCC, the ACI method is covered.

WSDOT Mix Design Methods

Currently, WSDOT uses both the Hveem and Superpave mix design methods. However, Superpave is slated to eventually phase out the older Hveem method.

Figure 5.1: U.S. Mix Design Methods
(from Tandon and Avelar, 2002; ERES, 1998; White, 1985 and Vallerga and Lovering, 1985)

Performance Tests. These are the tests performed on laboratory designed mixes (or field samples) to characterize their performance. They can consist of basic physical property measurements (such as stiffness or strength) or laboratory simulation of field conditions (such as rutting potential or chloride penetration).

This section is only meant to provide a brief overview of mix design methods as well as their assumptions, inputs and outputs. Resources that provide a detailed description and analysis of each mix design method are listed in the beginning of each section.