Session 4 Preventive Maintenance Treatments

Learning Objectives 1.Identify typical preventive maintenance techniques used on HMA and PCC pavements 2.Identify the purpose/effectiveness and feasibility of preventive maintenance treatments Upon completion of this module, you will be able to:

Preventive Maintenance Treatments  Available treatments  HMA pavements  PCC pavements  Purpose of individual treatments  Acceptable pavement conditions for application (feasibility)

PM Techniques for HMA-Surfaced Pavements HMA

Preventive Maintenance Technique Types  Crack treatments  Surface treatments  Recycling treatments  Milling and thin HMA overlays  Maintenance of drainage features HMA

Crack Treatments Crack Treatments Purpose Used to prevent water and debris from entering individual cracks in the HMA pavement surface HMA

Crack Sealing Distress Type Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Extent of Problem Minor Major HMA Feasible Not Appropriate Feasibility Effective Marginal No Impact Effectiveness

Surface Treatments Surface Treatments Purpose Typically used to:  Seal cracks  Waterproof surface  Improve friction  Improve rideability  Rejuvenate surface HMA

Surface Treatments Types  Fog seal  Slurry seal  Microsurfacing  Chip seal  Scrub seal  Ultrathin friction course  Others? HMA

Light application of diluted, slow-setting asphalt emulsion without aggregate cover Description Purpose   Seal pavement   Inhibit raveling   Enrich hardened/oxidized asphalt   Provide delineation with shoulder Fog Seal HMA

Distress Type Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Extent of Problem Minor Major HMA Feasible Not Appropriate Feasibility Effective Marginal No Impact Effectiveness

Slurry Seal Mixture of well-graded aggregate and slow setting asphalt emulsion Description Purpose   Seal surface cracks   Correct raveling/oxidation   Fill minor surface irregularities and restore friction HMA

Slurry Seal Distress Type Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Extent of Problem Minor Major HMA Feasible Not Appropriate Feasibility Effective Marginal No Impact Effectiveness

Microsurfacing Mixture of high-quality aggregates and polymer-modified emulsion binder Description Purpose   Inhibit raveling and surface oxidation   Improve surface friction   Fill ruts/minor surface irregularities   Seal pavement surface HMA

Microsurfacing Distress Type Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Extent of Problem Minor Major HMA Feasible Not Appropriate Feasibility Effective Marginal No Impact Effectiveness

Chip Seal Application of asphalt and aggregate chips rolled onto the pavement Purpose   Seal pavement   Enrich hardened/oxidized asphalt   Retard reflection cracking on HMA overlays   Improve surface friction Description HMA

Chip Seal Distress Type Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Extent of Problem Minor Major HMA Feasible Not Appropriate Feasibility Effective Marginal No Impact Effectiveness

Scrub Seal Application of sand or small-sized aggregate on broomed layer of polymer-modified asphalt Purpose   Fill and seal small cracks and voids   Enrich hardened/oxidized asphalt   Preparation for another treatment Description HMA

Scrub Seal Distress Type Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Extent of Problem Minor Major HMA Feasible Not Appropriate Feasibility Effective Marginal No Impact Effectiveness

Ultrathin Friction Course Gap-graded, polymer- modified HMA placed on a heavy, polymer- modified emulsified asphalt tack coat Purpose   Increase surface friction   Address surface distress   Reduce noise Description HMA

Ultrathin Friction Course Distress Type Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Extent of Problem Minor Major HMA Feasible Not Appropriate Feasibility Effective Marginal No Impact Effectiveness

Recycling Treatments Recycling Treatments Purpose Typically used to:  HMA to a depth of 50 to 100 mm (2 to 4 inches)  Rework HMA to a depth of 50 to 100 mm (2 to 4 inches)  Correct surface distresses  Improve profile, crown, and slope HMA

Recycling Treatments Types  Cold In-Place Recycling (CIR)  Hot In-Place Recycling (HIR) HMA

Cold In-Place Recycling Milling, rejuvenating, and replacement of the top portion of the HMA surface (performed without heat) Purpose   Rework HMA to depth of 50 to 100 mm   Correct surface distresses   Improve profile, crown, and cross-slope Description HMA

Hot In-Place Recycling Milling, rejuvenating, and replacement of the top portion of the HMA surface (performed with heat) Purpose   Rework HMA to depth of 25 to 50 mm   Correct surface distresses   Improve profile, crown, and cross-slope Description HMA

Cold and Hot In-Place Recycling Distress Type Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Extent of Problem Minor Major HMA Feasible Not Appropriate Feasibility Effective Marginal No Impact Effectiveness

Milling with Thin HMA Overlay Application of a new HMA wearing course after milling of the top portion of the HMA surface Purpose   OGFC reduce hydroplaning and tire splash   Improve rideability and surface friction   Improve profile, crown, and cross-slope Description HMA

Milling with Thin HMA Overlay Distress Type Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Extent of Problem Minor Major HMA Feasible Not Appropriate Feasibility Effective Marginal No Impact Effectiveness

Maintenance of Drainage Features Any activity that will improve the drainability of a pavement section Description Purpose Minimize time to remove infiltrated or surface water Recommended Use Strongly recommended on all HMA pavements HMA

PM Techniques for PCC-Surfaced Pavements PCC

Common PM Techniques for PCC-Surfaced Pavements  Joint/crack sealing  Diamond grinding  Diamond grooving  Undersealing  Load transfer restoration  Maintenance of drainage features PCC

Joint/Crack Sealing Application of a sealant material in concrete pavement joints and cracks Purpose   Minimize moisture infiltration   Prevent intrusion of incompressibles Description PCC

Joint/Crack Sealing Distress Type Linear Cracking Corner Breaks Transverse Joint Faulting Joint Spalling D-Cracking Pumping Roughness Friction Loss Surface Distress Extent of Problem Minor Major HMA Feasible Not Appropriate Feasibility Effective Marginal No Impact Effectiveness

Diamond Grinding Removal of a thin layer of PCC using stacked diamond tipped cutting blades Purpose   Remove faulting   Improve surface rideability   Improve surface friction Description PCC

Diamond Grinding Distress Type Linear Cracking Corner Breaks Transverse Joint Faulting Joint Spalling D-Cracking Pumping Roughness Friction Loss Surface Distress Extent of Problem Minor Major HMA Feasible Not Appropriate Feasibility Effective Marginal No Impact Effectiveness

Diamond Grooving Creation of narrow grooves in the PCC surface using diamond tipped cutting blades (localized areas) Purpose Reduce hydroplaning and wet weather accidents Description PCC

Diamond Grooving Distress Type Linear Cracking Corner Breaks Transverse Joint Faulting Joint Spalling D-Cracking Pumping Roughness Friction Loss Surface Distress Extent of Problem Minor Major HMA Feasible Not Appropriate Feasibility Effective Marginal No Impact Effectiveness

Undersealing Pressure insertion of flowable material beneath a PCC slab Purpose   Fill underlying voids (not raise slab)   Reduce pavement deflections   Minimize pumping and faulting Description PCC

Undersealing Distress Type Linear Cracking Corner Breaks Transverse Joint Faulting Joint Spalling D-Cracking Pumping Roughness Friction Loss Surface Distress Extent of Problem Minor Major HMA Feasible Not Appropriate Feasibility Effective Marginal No Impact Effectiveness

Load-Transfer Restoration Placement of load transfer devices across joints or cracks in an existing pavement Purpose   Provide reliable load transfer   Reduce or eliminate pumping, faulting, and corner breaks (reducing deflections) Description PCC

Load-Transfer Restoration Distress Type Linear Cracking Corner Breaks Transverse Joint Faulting Joint Spalling D-Cracking Pumping Roughness Friction Loss Surface Distress Extent of Problem Minor Major HMA Feasible Not Appropriate Feasibility Effective Marginal No Impact Effectiveness

Maintenance of Drainage Features Any activity that will improve the drainability of a pavement section Description Purpose Minimize time to remove infiltrated or surface water Recommended Use Strongly recommended on all PCC pavements PCC

Other PM Techniques? Do you use any techniques other than those listed?

PM Techniques for Shoulders? What’s different? What’s the same?

Review of Learning Objectives 1.Identify typical preventive maintenance techniques used on HMA and PCC pavements 2.Identify the purpose/effectiveness and feasibility of preventive maintenance treatments