Caltrans Maintenance Technical Advisory Guide (MTAG) R. Gary Hicks Brian Toepfer, Caltrans Jason Dietz, FHWA Prepared for PPTG Southern California Local Agencies August 15, 2006
PRESENTATION AGENDA 1. Background 2. Organization of MTAG Pavement Preservation and Materials Treatment Selection Treatment Chapters Other Guides on Pilot Treatments 3. Use and Benefits of MTAG 4. Conclusions and Recommendations
BACKGROUND Caltrans maintenance program shifted from reactive to proactive pavement preservation This created a need for technical support in the use of various maintenance treatments t t MTAG-Flexible Pavement developed in 2002; MTAG-Rigid id Pavement developed d in 2006
Introduction What is Pavement Preservation? Materials used for pavement preservation treatments Typical pavement structures and their design Common distresses in pavement structures
Pavement Preservation (PP) Caltrans Definition Sum of all activities iti to provide and maintain i serviceable roadways Corrective & Preventive Maintenance (30mm) Minor & Major Rehab (CAPM) State Highway Operation Pavement Program (SHOPP) delay is PP
Pavement Preservation Concept Original Pavement on onditio Co Optimal Timing Preventive Trigger Rehabilitation Trigger Time or Traffic
Materials used in PP Treatments Binders and/or cements Aggregates Additives Storage and Handling Sampling
Framework for Strategy Selection Overall Goals Approach for selecting maintenance treatments LCCA approach
Goals for Strategy Selection Establish when and where to use various PP strategies based on current pavement condition data Identify the performance of the various treatments (e.g. Expected life or life extension) Determine the cost effectiveness for the various strategies based on LCCA
Typical Caltrans PM Treatments AC Crack Seal/Fill Seals (Fog, Slurry, Chip) Thin HMA Overlays Micro-Surfacing * Bonded Wearing Course PCC Joint Resealing and Crack Sealing Diamond Grinding Dowel Bar Retrofit Isolated Partial and Full Depth Concrete Repair * Surface recycling not currently used by Caltrans
Maint. Treatments in the MTAG-Flexible Pavements Crack Seals - Chapter 3 Patching and Edge Repair - Chapter 4 Chip Seals - Chapter 5 Fog Seals - Chapter 6 Slurry Seals - Chapter 7 Thin Hot Mix Overlays - Chapter 8 Microsurfacing and Thin Bonded Overlays are separate documents because of pilot status
Maint. Treatments in the MTAG-Rigid Pavements Surface Characteristics Chapter 2 Joint Resealing and Crack Sealing - Chapter 4 Diamond Grinding - Chapter 5 Dowel Bar Retrofit - Chapter 6 Isolated Partial and Full Depth Concrete Repair - Chapter 7
Benefits of PP Treatments Life extension of the existing pavement Reduced noise, depending on the treatment Improved ride quality Improved skid resistance and safety (reduced splash & spray) Reduce user delays
Life Extension Factors affecting life extension Condition of existing pavement Climate Traffic Timing of treatment Validation of life extension - data not yet available in CA
Definition of Life Extension Very Good Good Measured Life Extension Fair Poor Very Poor PMS Data Point Time (Years)
Selecting Maintenance Treatments The Caltrans Approach Developed in 2003 for flexible pavements; proposed in 2006 for rigid pavements Factors considered Existing pavement condition Traffic Climate Geography/Topography Once the treatment is selected, cost and other factors are used to select the most effective treatment
Treatment Selection Guide Flexible Pavements Preventative Maintenance Good Reconstruction Defer Action Poor Rehabilitation Time (Years)
Outline of Chapters on Typical Treatments Used by Caltrans Introduction/description Project selection considerations Materials, design and specifications Construction procedures Field testing Troubleshooting References Only a few of the treatments will be covered
Fog Seals Used extensively by Caltrans Materials used Conventional emulsions Rejuvenating Seals Use restricted to certain areas Expected life is 2-4 years Light application of asphalt emulsion or rejuvenating agent Material applied using conventional spraying equipment Used to retard oxidation and/or restore pavement surface condition, e.g., tighten cracks or hold loose rocks
Chip Seals Binder types Chips seals used by Caltrans Single chip seal Multiple chip seal Stress absorbing membrane interlayer Asphalt emulsions-including PM and rejuvenating Asphalt cements-can be placed in cooler conditions Asphalt rubber
Benefits of Chips Seals Why Use Them Can be placed in single or multiple layers, typical application rate of single layer is 20-25 #/yd 2 Seals cracks in existing pavement Protects the pavement surface from water intrusion and oxidation Provides a friction resistant surface Expected life is 4-8 years
Slurry Seals Used extensively in California Normally use slow set or quick set emulsions Microsurfacing is now being used extensively and will eventually be added to the MTAG Materials - a mixture of graded aggregate, g asphalt emulsion, additives and often polymers Design Considerations - a special mix design needs to be carried out
Benefits of Slurry Seals Why Use Them Seals surface cracks of the pavement like a chip seal Minimizes aggregate loss Improves surface friction Expected life is 4-8 years Cost t effective
Thin Hot Mix Overlays (<30 mm) Dense Graded - Type A and B Mixes Gap Graded - Asphalt Rubber Open Graded - Asphalt and Asphalt Rubber Thin HMA overlays have been used either alone or in combination with a SAMI
Benefits of Thin HMA Overlays Why Use Them Industry standard Years of experience Versatile, used in many different applications Reasonable cost Pavement drains rapidly reducing hazard of hydroplaning Reduced spray from vehicles Improved friction resistance Cost-effective under certain conditions
Surface Characteristics Important Surface Characteristics Ride Texture e Surface Friction Noise Definition Measurement Equipment and Practices
Joint Resealing & Crack Sealing Purpose Reduce infiltration of surface moisture Prevent imcompressible ibl materials into the joints and cracks Project Selection The base should be sound The existing structure should be structurally adequate Design Considerations Materials Reservoir design Special considerations for cracks Construction Process Traffic control and safety Installation process Quality control
Diamond Grinding Purpose Restore ride quality and surface texture Reduce hydroplaning Project Selection Worn surface Faulting at joints and cracks Design Considerations Aggregate type Blade spacing Construction Process Traffic control and safety Work sequences Quality control
Purpose Dowel Bar Retrofit Restore load transfer efficiency Reduce faulting and deterioration ti at joints Project Selection Structurally sound pavement with adequate thickness but exhibiting loss of load transfer Pavement with inadequate load transfer Design Considerations Load transfer device Dowel bar layout Backfill Construction ti Process Traffic control and safety Installation process Quality control
Purpose Isolated Partial and Full Depth Concrete Repair Restore structural integrity and rideability Project Selection Distress types and conditions Structural adequacy Design Considerations Concurrent work Repair location and boundaries Load transfer Construction Process Traffic control and safety Repair process Quality control
Use and Benefits of MTAG All chapters include a checklist and trouble shooting Available to personnel on the web Proven to be a valuable technical resource Answers typical questions Virtually eliminates need for calls to headquarters www.dot.ca.gov/hq/maint/mta_guide.htm / t/mta id ht
Conclusions and Recommendations Conclusions MTAG is a valuable resource Provides technical assistance to DMEs and others Recommendations Needs to be supported by training Needs to be updated periodically to reflect changes in specs and processes
Questions?