Highway Maintenance and Rehabilitation PDF

**MODULE 7: Highway Maintenance and Rehabilitation** Highway Maintenance - Routine work performed to keep a pavement under normal conditions of traffic and normal forces of nature, as nearly as possible in its original condition (monitoring pavement health) - Maintenance actions help...

**MODULE 7: Highway Maintenance and Rehabilitation** Highway Maintenance - Routine work performed to keep a pavement under normal conditions of traffic and normal forces of nature, as nearly as possible in its original condition (monitoring pavement health) - Maintenance actions help slow the rate of deterioration by identifying and addressing specific pavement deficiencies that contribute to overall deterioration Maintenance Operations - Surface maintenance - Road side maintenance - Shoulder and approaches maintenance - Bridges, tunnels, and drainage structure maintenance - Traffic controls and safety devices (road signs, pavement markings, traffic signals, and road lighting) Maintenance of Road Surfaces 1. Bituminous Surfaces - failures due to weathering, failure of base or subgrade due o material quality or compaction or improper drainage - Repairs: - Patching - Scarifying - Resealing - Non skid surface treatment 2. PCC Surfaces - Repairs: - Filling and sealing of joints and cracks - Repairing spalled, scaled, and map cracked areas - Patching areas where failure has occurred - Reaping areas damaged by settlement and pumping - Treating buckled pavement 3. Maintenance of Shoulders and Approaches - Approaches include public side roads, private driveways, ramps. Speed change lanes, and turnouts - Approach maintenance is similar to main roadway maintenance 4. Maintenance of Roadsides - Roadside include area between traveled surface and the limit of the right-o-way (medians, roadside parks, ROW fences, etc.) - Vegetation management and control (include mowing, weed eradication and control, seeding, planting vegetations, and care of trees and shrubs) - Maintenance of rest areas 5. Maintenance of Bridges, Tunnels, and Drainage Structures - Bridges need to minimize deterioration or repair damage caused by accidents, floods, or other unforeseen events - Steel bridges need to be cleaned and painted to precent erosion - Concrete bridge decks may deteriorate due to the corrosion of reinforcement bars due to penetration of water and de-icing salts or chemicals - Bridge deck with minor deterioration is to be patched with special concrete - For major deterioration it is to be overlayed or removed and constructed - Tunnels (special attention areas): - Supports -- check for decays - Tunnel walls and ceilings -- check for leaks - Portals -- free from loose rocks - Lighting -- for visibility - Ventilation - Drainage Structures (following should be kept in good condition:) - Surface drainage - Ditches - Culverts - Traffic Control and Safety Devices - Guardrails, barriers, impact attenuators, pedestrian overpasses and underpasses, fence to restrict access of pedestrians and animals - Safety devices should be frequently and systematically inspected and repaired Pavement Rehabilitation - Proper maintenance to extend pavement life - However, the best-maintained pavements will deteriorate with time and will need rehabilitation - Conventional rehabilitation: - Reconstruct with all new materials - Patch and overlay with new wearing surface - Due to high construction cost, new methods of rehabilitation are raised: - Pavement Milling -- surface layers can be removed with a milling machine and replace with new hot-mix - Pavement Recycling -- technique where an existing degraded pavement is modified and transformed into a homogeneous structure that can support the traffic requirements **MODULE 8: Recycling Equipment and Methods** Recycling - Action or process of converting waste into reusable material Recycling Highways - Using recovered concrete, brick, and asphalt materials for the construction of pavements, earthworks, and drainage - This provides potential cost savings and conservation of natural resources Pavement Recycling - Technique where an existing degraded pavement is modified and transformed into a homogeneous structure that can support the traffic requirements - A report from the Federal Highway Administration shows that 80 percent of asphalt pavement that's removed each year during widening and resurfacing projects is reused Asphalt Pavement Recycling - Four primary methodologies in pavement recycling 1. Hot Recycling - Hot Mix Asphalt or Warm Mix Asphalt containing Recycled Asphalt Pavement (RAP) 2. Hot In-place Recycling (HIR) 3. Cold Recycling - Cold In-place Recycling (CIR) - Cold Central Plant Recycling (CCPR) 4. Full Depth Reclamation (FDR) Hot Mix Asphalt (HMA) and Warm Mix Asphalt Recycling - Process in which Reclaimed Asphalt Pavement (RAP) is combined with new materials to produce HMA/WMA mixes - RAP material can be obtained by milling or a crushing operation - RAP percentages range from 10 to 50 percent - Produced by batch plants or drum plants - Batch Plant -- make small accurate batches of asphalt mixture through a process that is repeated over and over until the total tonnage for a project has been manufactured - Drum Plant -- prepare the asphalt mix through a continuous process and require the use of silos for temporary storage prior to the mix being trucked to the paving location Hot In-place Recycling (HIR) - Method where the existing pavement is heated and softened, and ten scarified/milled to a specified depth - New HMA/WMA (with or without RAP) and/or recycling agent may be added to the scarified RAP material during the recycling process - HIR can be performed either as a single pass or as a multiple pass operation - Single Pass -- scarified in-place material can be combined with new material if needed or desired - Multiple Pass -- restored RAP material is recompacted first, and a new wearing surface is applied later - Three HIR Processes: 1. Surface Recycling 2. Repaving 3. Remixing Surface Recycling - Primary purpose of the surface recycling process is to eliminate surface irregularities and cracks - Equipment consists of the following: 1. Preheating unit 2. Heating and recycling unit 3. Rubber-tired roller Repaving - Useful when the surface recycling process is not sufficient to restore the pavement's desirable surface requirements or when a conventional HMA overlay is impractical or not needed - Equipment: 1. Preheating unit 2. Heating and recycling unit 3. Rubber-tired roller 4. Paver Remixing - Used when repaving method is not sufficient to restore the pavement to its desirable properties and additional aggregates or new HMA mix are required to provide strength and stability to the existing pavement - Process can effectively eliminate rutting, cracking, and oxidation (hardening) in the upper 50 mm (2 in) of the pavement surface - Asphalt pavements with one seal coat are remixable and the seal coat may help in softening the recycled binder - Pavements with multiple seal coats can create smoke and fire t the surface and act as an insulator against the heating of the underlying pavement Cold In-place Recycling - Existing pavement is pulverize in-place and recompacted into a pavement layer - Either as foamed asphalt binder or an asphalt emulsion is added as a recycling agent or binder Cold Central Plant Recycling (CCPR) - Material removed from an existing pavement I transported to a central location -- either on the project site or an existing asphalt plant - Either a foamed asphalt binder or an asphalt emulsion is added as a recycling agent or binder Full Depth Reclamation (FDR) - Recycling method where all of the asphalt pavement section and a predetermined number of underlying materials are mixed and manipulated in-place and treated t produce a stabilize base course - Steps: 1. Pulverization 2. Introduction of additive 3. Shaping of the mixed material 4. Compaction 5. Application of a surface or a wearing course - Performed at a depth of 4 to 12 inches