7. FDR Definition FDR is a process in which the existing asphalt surface is Pulverized in place and blended with the underlying base, sub-base, and/or subgrade materials, mixed with Portland Cement, and compacted to provide a new stabilized base that is high strength, non-plastic, and less permeable. A new surface course is then applied, which completes the FDR process.
8. FDR SHOULD BE USED WHEN: ■ SERIOUSLY DAMAGED PAVEMENT ■ BASE OR SUB-BASE FAILURE ■ PATCHING OVER 15%-20% of PROJECT AREA ■ TRAFFIC LOADING EXCEEDS DESIGN
18. ECONOMIC CHALLENGE -”Best First Approach” doesn’t address all roads -Projected funding can not keep up -Increasing rehab costs
19. Project Profile Bancroft Avenue, San Leandro 2-lane Major Collector, 136,000sft. 4” AC over 12” FDR using 5% cement $4.05/sft. - FDR Cost $7.36/sft. - Traditional Pavement Cost HSI Engr’g & Inspection Services Fee= 3% const.
20. ENVIRONMENTAL & ECONOMIC SAVINGS FDR VS. REMOVE/REPLACE (50,000 sft. , 12-in Deep ) 120 Loads Export Number of Trucks Required 146 Loads of Aggregate Import 4 Loads of Cement Material Required (Tons) 3,650 Tons New Aggregate 108 Tons of Cement Diesel Fuel Consumed (Gal) 3,920 Gallons 480 Gallons FDR Process Remove/ Replace Process
30. HSI FDR SERVICES Coring/Sampling Lab Analysis Mix Design Strength Determination Contract Documents Construction Inspection / Support
31. A standardized structural value is given to the stabilized base: Caltrans Design Equation: Gf = 0.9 + (UCCS/1000) UCCS in psi Minimum Unconfined Strength = 300 psi Minimum Thickness = 10 inches Maximum Thickness = 18 inches FDR DESIGN “Making a Better Aggregate Base”
41. THE PROCESS Start to Finish in about 3-5 Days START 1. Before Full-Depth Rehabilitation 2. Pulverize Pavement 3. Re-Shape Grade 4. Apply Cement 5. Mix & Hydrate Cement 6. Initial Compaction FINISH 7. Final Grading 9. Pave FDR 8. Final Compaction & Curing
42. STEP 1: PULVERIZE EXISTING BASE SUBGRADE PULVERIZED EXISTING BASE SUBGRADE
47. IS OFFHAUL REQUIRED? 100% Recycle In-Place No grade restraints allows for 100% In-place recycling Re-establish Crown allows for additional use of recycled material 75% to 100% Recycle In-Place Remove existing AC to allow for new AC section 65% to 80% Recycle In-Place Curb & Gutter Conform to established grades
48. STEP 3: SPREAD CEMENT Spreading of Stabilizer PULVERIZED SUBGRADE On-board controls provide for ametered material application. Mechanical vane spreader allows for uniformdistribution.
49. STEP 4: MIX & HYDRATE Complete mixing, hydration and compaction within 2 hours.
54. CONSTRUCTION QUALITY CONTROL Moisture Gradation Density Compact between 93% and 95% modified proctor (ASTM D1557). -100% pass 2-inch sieve -minimum 95% pass 1-inch sieve, and a minimum of 55% passing No. 4 sieve Add moisture for Compaction and moisture for Cement Hydration for minimal shrinkage.
55. MOISTURE CONSIDERATION Allowable Moisture Range @ 95% Required Moisture for Cement Hydration @ 2 cement to 1 water Relationship Maximum Density Moisture Content Relationships Cement - Allow for cement hydration prior to compacting (Approx.. 30 min from final mixing) 95% of Maximum Optimum Cure Moisture Range Optimum Moisture
PRIOR TO STARTING:Confirm location of UtilitiesLower all Structures if possibleNotify all impacted Residence & BusinessesJob Walk-throughPULVERIZE EXISTING SECTION
![OUTLINE What is FDR? Challenges of traditional design Benefits of using FDR? ,[object Object]](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)