Mix Design: Tying It All Together

The document provides guidance on material selection, testing procedures, and troubleshooting for asphalt mix design and quality control during production.

Material Selection and Specifications

• Use aggregates from approved sources and ensure they meet specifications.
• Select asphalt binder from approved sources or provide samples for testing.
• Decide on additive lime WMA and check for compatibility.
• Determine recycled material content based on performance and specifications.

Testing Procedures for Mix Design

• Sample aggregates and perform gradation tests according to Tex-221-F and Tex-200-F.
• Use Tx2MixSolver to optimize gradation and verify limits.
• Prepare mix mold specimens for density and asphalt content testing.
• Verify design through repeated molding and density checks at optimal asphalt content.

Troubleshooting Failing Mix Designs

• Check lab equipment calibration and technician procedures.
• Compare production gradation with design and adjust bin percentages.
• Ensure stockpile moisture content is within acceptable limits.
• Inspect loading, belt alignment, and equipment operation for issues.

Addressing Hamburg and Overlay Failures

• Investigate additive compatibility and gradation issues.
• Consider anti-strip agents, polymer binders, or binder content adjustments.
• Test mineral filler reactivity with water.
• For overlay failures, ensure adequate binder content and proper mix proportions.