FULL DEPTH RECLAMATION...Hydrated Lime – Dry or Slurry (1-2%) Portland Cement & Hydrated Lime have...
Transcript of FULL DEPTH RECLAMATION...Hydrated Lime – Dry or Slurry (1-2%) Portland Cement & Hydrated Lime have...
Cold Recycling
Overview
► Asphalt pavements eventually develop distress such as:
CrackingRavelingPot holesPoor Ride Quality
► Traffic, weather and hardening of the asphalt binder all contribute to these problems.
Introduction
► Cold Recycling is a process whose time has come…
environmentally soundgives enhanced performanceand saves dollars.
Types of Cold Recycling
► Cold Central Plant Recycling (CCPR)
► Cold In-Place Recycling (CIR)
CIR – Process Description
► Pulverizing existing pavement (2-5”)► Sizing of the reclaimed asphalt► Addition of new binder/additives► Mixing all component materials► Placement of the mixture► Compaction of the mixture
CIR – Cross Section
Classes of CIR
Multi-Unit Train Pulverize, Screen, Crush, Add Recycling Agent Based on RAP Weight & Mix in Pugmill
Two-Unit Train Pulverize, Add Recycling Agent Based on RAP Weight & Mix in Pugmill
Single Unit Train Pulverize, Add Recycling Agent – All in Cutting Chamber of Milling Machine
CIR – Multi-Unit Train
Multi-Unit Train
► Cuts to precise depth & width specified► Adds mixing water/liquid additives► Processes one full lane width► Propels the train► Pushes tankers ► Highly productive
Multi-Unit Sizing
► All reclaimed asphalt pavement (RAP) is screened to achieve a maximum size requirement(typically 1.25”).
► Oversized material is crushed and returned to the screen deck for total sizing control.
Multi-Unit Pugmill
► Belt scale weighs RAP, computer controls additives
► Multiple additives may be added simultaneously
► Pugmill thoroughly blends RAP and additives
Two-Unit Train
Single Unit Train
►Small size for urban projects►Short turning radius
Single Unit Train
►Pulverizing, sizing and mixing of Recycling Agent with RAP all take place in the milling machine down-cutting head.
►Proportioning of Recycling Agent is based on depth and width of cut and forward speed of train.
CIR - Laydown
Traditional Asphalt Pavers Used or …
CIR - Laydown
Mix Pavers may be also be used
CIR - Laydown
► Cold In-place Recycling laydownis done with the same equipment and controls as other maintenance mixes.
CIR - Compaction
Rollers necessary for CIR include a heavy pneumatic roller(s) (25 ton) and a steel wheeled roller(s)
CIR –Widening
CIR –Widening
Additional aggregate may be placed in the area to be widened.
CIR –Widening
CIR - Benefits
►Conserves Energy►Conserves Materials►Improves Mix Characteristics►Cracking Eliminated/Reduced►Improves Geometrics►Cost Effective►Saves Time►May Be Performed Under Traffic
CIR – Pavement Types
►Airport Runways►County Roads►State & US Highways►Interstate Highways►City Streets
CIR - Candidates
Thermal Cracking
Fatigue Cracking
Patched
Dry, Raveled
Poor Rideability
CIR – Project Selection
►Material Properties Evaluation►Existing Road Geometrics►Life Cycle Cost Analysis►Environmental Impact►Structural Strength►Pavement Condition►Road History►Traffic Study
CIR – Mix Design
1. Obtain Sample of RAP from Field2. Determine RAP Gradation, Binder Content,
Extracted Gradation and Aged Binder Properties
3. Select Amount and Gradation of Additional Aggregate, if required
4. Select Type and Grade of Recycling Additive5. Determine Pre-Mix Moisture Content6. Test Trial Mixtures: Initial Cure Properties, Final
Cure Properties, and Water Sensitivity7. Establish Job Mix Formula
CIR – Additive Selection
Asphalt Additives:► Asphalt Emulsion (w/ & w/o polymer)
Anionic Emulsions●HFMS-2●HFMS-2s
Cationic Emulsions●CSS & CMS
► Rejuvenating Agents► Foamed Asphalt
CIR – Additive Selection
Chemical Additives:► Portland Cement – Dry or Slurry (1-2%)► Hydrated Lime – Dry or Slurry (1-2%)► Portland Cement & Hydrated Lime have
been used in conjunction with asphalt emulsion to improve early strength,
increase rut resistance and improve moisture resistance
► Fly Ash – Class C Fly Ash (8-12%)► Used to cement RAP particles together
CIR – Additive Application
Dry Application.
Type C Fly Ash, Portland Cement or Hydrated Lime may be spread dry in front of the recycling train.
Slurry Application.
Portland Cement and Hydrated Lime may be applied in slurry form.
CIR – Aggregate Application
► The existing asphalt pavement properties may be enhanced with the addition of aggregate or RAP.
► The mix properties be improved and additional structure may also be added to the asphalt pavement.
CIR – QA/QC Plan
1. Calibration of meters2. RAP Gradation3. Recycling Additive4. Recycled Mat Smoothness5. Moisture added to RAP6. Compacted Density7. RAP Gradation8. Moisture content before overlay9. Recycling additive content10. Depth of pulverization/milling
Surface Treatments
Chip SealSlurry SealMicro-SurfacingCold Mix OverlayHot Mix Overlay
Cold Central Plant
► Cold Central Plant Recycling (CCPR) is a viable alternative when stockpiles of high quality RAP are available or when it is not possible to in-place recycle the pavement.
CCPR - Process
► Aggregate Feeding/Blending► Screening/Crushing► Liquid Metering Systems► Pugmill Mixing
CCPR - Applications
► Stockpile Mix. When the recycled cold mix is to be stockpiled for later use, an emulsion with cutters, such as diesel fuel, may be used. Rejuvenators may also be used to enhance mix workability.
CCPR - Applications
► Immediate Lay. When the recycled cold mix is to be placed immediately a quicker setting emulsion may be used.
Weather Limitations
►Air Temperature of 50 Degrees F. is preferred.
►Heavy Rain must not be occurring.
CIR Advantages
►Conserves Energy►Conserves Materials►Improved Mix Characteristics►Cracks Eliminated/Reduced►Cost Effective►Saves Time►May Be Performed Under Traffic.
After Overlay
Questions ???