California Pavement Preservation Center

Ongoing Research

Caltrans California Pavement Preservation Contract

Task 1. Training and Educations

The objective of this task is to provide training and education for Caltrans on pavement in California.

Task 2. Encourage Innovation and New Technologies in Pavement Preservation

The objectives of this task are to improve pavement preservation treatment performance by:

  • Facilitating and documenting Innovation projects. Documenting the construction and performance of non-innovations pavement preservation projects.
  • Assisting Caltrans with the identification, certification, and implementation of new products

Task 3. Provide Technical Assistance on Pavement Preservation Related Issues

The objective of this task is to assist Caltrans in the area of pavement preservation by providing technical assistance.

Task 4. Promote Effective Pavement Preservation Practices

The objective of this task is to promote effective pavement preservation practices within California using a variety of different means and using the technical information developed in Tasks 1-3.

NCHRP 40-13 Recycling and Reclamation of Asphalt Pavements Using In-Place Methods

In-Place Recycling Document Assessment Link

NCHRP 40-13

In recent years, petroleum and aggregate economics and supply have increased the need for high quality, cost effective alternatives to virgin paving mixtures. Transportation professionals are asking for methods that optimize the value of in-place materials while minimizing traffic congestion and the environmental impact of paving operations. Current pavement recycling and reclamation methods answer all of these needs, in particular -

  • Hot In-Place Recycling (HIR)
  • Cold In-Place Recycling (CIR) and
  • Full-Depth Reclamation (FDR)

These techniques provide economical and sustainable solutions that reduce demand on raw materials, energy consumption, and production of GHG, while maintaining functionality and performance.

Key issues to be addressed include the need for specific in-place recycling and reclamation strategies and a discussion of how they might be used within the planned life-cycle of a pavement.  Information to be collected for this study includes:

  • Project selection criteria 
  • Pavement condition, traffic, geometric and environmental considerations
  • In-place material testing and evaluation, including recyclability of existing materials 
  • Criteria used for selection of strategies
  • Extent of annual construction program for each of the three strategies (including rationale for use)
  • Types of liquids or stabilizers used to condition the RAP
  • Mixture design methods
  • Structural design considerations
  • Processing methods and equipment
  • Inspection and quality assurance
  • Wearing course considerations
  • Barriers to implementation, including: lack of engineering design standards; lack of evidence that it will work; lack of local, experienced contractors
  • Tried it and it failed
  • Opposition from competing industries 
  • Data on documented performance, costs, and benefits
  • Quantification of environmental benefits  

Ongoing Research

NCHRP 40-01 Recycled Materials and Byproducts in Highway Applications Synthesis

NCHRP 40-01 information
Information to be gathered for the synthesis will include:

  • A comprehensive list of current candidate materials that are readily available or stockpiled for common usage,  and their uses, in a matrix format
  • Identify and review available test procedures for assessing physical and chemical characterization, compaction, geomechanical properties, long-term durability, and environmental performance, including suitability and risks
  • Summarize best material preparation and quality control techniques (including stockpiling)
  • Review possible modifications to transform marginal materials into suitable materials.  This includes mechanical, chemical or environmental strategies.
  • Address material handling issues associated with the use of recycled  materials
  • Explain design adaptations that may be required for successful use
  • Identify site construction practices that have proven effective
  • Identify failures, causes, and lessons learned
  • Identify the major scientific, contractual and perceptual barriers to adoption of suitable alternative materials by states and steps used to overcome these barriers
  • Cost savings from use of recycling, including energy and materials  
  • Gaps in knowledge and a research road map to address these

We are currently collecting information on a wide range of recycled materials and by-products. Content Assessment surveys have been developed for these topics (shown below).

If you want to log a document into our database, please click on the recycled material or byproduct then answer the Content Assessment questions.

Blast Furnace Slag(opens in new window)

Coal Burning Ash(opens in new window)

Hot Mix Asphalt(opens in new window)

Kiln Dust(opens in new window)

Mineral Processing Material(opens in new window)

Municipal Solid Waste Combustor Ash(opens in new window)

Non-Ferrous Slag(opens in new window)

Pulp and Paper(opens in new window)

Quarry Waste(opens in new window)

Reclaimed Asphalt Pavement(opens in new window)

Reclaimed Concrete(opens in new window)

Roofing Shingle(opens in new window)

Scrap Tires(opens in new window)

Sewage Sludge(opens in new window)

Steel Slag(opens in new window)

Waste Glass(opens in new window)

Please use the following link to provide basic information and locations for your recycling projects.

In-Place Recycling Project Location Database(opens in new window)

CalRecycle Projects on Warm Mix and Terminal Blends

The Center just completed a final report for this project. The reports are available on the center website. The results from this two years study indicated the following:

  • Terminal blends containing crumb rubber have been used in the United States since 1980s. They have been used in California since 1990s in both chip seals and hot mixes. The performance of these products have been very good.
  • Warm mix technology can be used with asphalt rubber hot mixes. They have not been used in the asphalt rubber spray applications.
  • Additional work is needed to evaluate the warm mix technologies with terminal blend and asphalt rubber.