Performance-Based Concrete Pavement Mix Design System
Mix Design?
It is the process of determining required and specifiable characteristics of a concrete mixture. Prescriptive approach (limits on materials). Performance approach (desirable characteristics). Mix design requirements are based on intended use, environment, etc.Mix design is the process of determining the quantities of concrete ingredients that meet the mix design criteria.
The primary considerations in mix proportioning include:
- The ability to continually meet or exceed specifications (durability and strength).
- Economy.
- Readily available supply of raw materials.
A typical laboratory testing plan includes the following mix characteristics:
- Workability.
- Strength.
- Plastic air content.
- Unit weight.
- Permeability.
- Coefficient of thermal expansion.
- Others depending on the mix design requirements.
The relative size and importance of a project determines which of these tests are performed.
Methods for Proportioning Concrete Mixes
- Water-cement ratio method.
- Weight method.
- Absolute volume method (ACI 211.1).
- Field experience (statistical data).
- New methodologies currently under development
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