Preventive Maintenance Treatments

Preventive Maintenance Treatments
Session 4 Preventive Maintenance Treatments There are many different techniques that are currently used to preserve and maintain existing HMA- and PCC-surfaced pavements. The objective of this session is to provide the participant with the knowledge to identify all of the “preventive maintenance” techniques that are considered feasible or appropriate for application on a given pavement section. Make point to tell the class that Module 3 in the associated “Reference Manual” (from course No ) contains much detailed information about available preventive maintenance techniques. p. 29 of reference manual contains information on treatments. p. 81 of reference manual contains a complete reference list that pertains to available treatments.

Learning Objectives Upon completion of this module, you will be able to: Identify typical preventive maintenance techniques used on HMA and PCC pavements Identify the purpose/effectiveness and feasibility of preventive maintenance treatments Point out what you want to accomplish in this module. The purpose is to briefly introduce treatments and talk about their applicability. On objective #2, we will focus on what condition can exist when applying different PM treatments. Also, introduce the focus of the second workshop—given your conditions, what types of treatments are appropriate.

Preventive Maintenance Treatments
Available treatments HMA pavements PCC pavements Purpose of individual treatments Acceptable pavement conditions for application (feasibility) In this module we look at a range of treatments. For all of the included treatments, we talk about the purpose of each treatment and the conditions under which it is appropriate. The information in this session will give us guidance on selecting feasible treatments for a specific project. Mention that in Workshop 3 we will focus on selecting the “best” or “most appropriate” treatment for a given project.

PM Techniques for HMA-Surfaced Pavements
We will start with a discussion of the preventive maintenance techniques that are associated with HMA-surfaced pavements (including asphalt overlaid pavements). HMA

Preventive Maintenance Technique Types
Crack treatments Surface treatments Recycling treatments Milling and thin HMA overlays Maintenance of drainage features The preventive maintenance techniques typically applied to HMA-surfaced pavements can be divided into these five general categories: Crack treatments (treatments applied to individual cracks). Surface treatments (thin treatments applied to a large area or the entire HMA-surface). Recycling treatments (treatments aimed at restoring the top couple of inches of the HMA-surface to its original properties). Milling and thin HMA overlays (the removal of the top portion of the surface layer and the replacement of that material with a new thin HMA [overlaid] surface). Maintenance of drainage features (general maintenance procedures to ensure a well draining pavement). Specific treatments included in each of these general categories will be discussed in detail in the following slides. HMA

Crack Treatments Purpose
Used to prevent water and debris from entering individual cracks in the HMA pavement surface Crack treatments are used to prevent water and debris from entering cracks in an HMA pavement. Limiting water infiltration protects the underlying pavement layers and reduces the detrimental effects of freeze thaw cycling. HMA

Crack Sealing Feasibility Distress Type Fatigue Cracking
Extent of Problem Distress Type Minor Major Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Feasible Not Appropriate GENERAL NOTES ON EXPLAINING THE CONTENTS OF THE BAR CHARTS: These charts mainly identify when a given treatment is NOT and option. That is, these charts collectively do not give you the answer, but they do help identify your feasible treatment options. Engineering judgment must be used in selecting the most appropriate treatment for a given project. Feasibility Chart This chart illustrates the maximum allowable distress types and levels that may be present when applying the current treatment. If the “extent of problem” for any one distress is outside of the feasible range, this particular treatment should be excluded from consideration (i.e., excluded from the feasible list). These are general SUBJECTIVE guidelines. Most likely, every State will differ from the ranges shown. These feasibility charts do not necessarily take multiple distresses into consideration, it ONLY shows the “maximum” allowable “extent of problem” for any given distress. For example, if a pavement has a medium linear cracking problem and a medium roughness problem, individual crack sealing activities would most likely NOT be used. Rather, a surface treatment would likely be used. Again, these charts are not intended to give you the answer, but instead, focus on eliminating treatments from consideration. HMA

Crack Sealing Effectiveness Distress Type Fatigue Cracking
Extent of Problem Distress Type Minor Major Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Effective Marginal No Impact Effectiveness (purpose) Chart This chart illustrates when the current treatment would be used (i.e., its purpose). Second, it indicates how effective the particular treatment is expected to be given the extent of different distresses (problems). Note: in these charts, “extent of problem” represents a combination of distress severity and amount. You should point out that the effectiveness chart does not really consider combinations of distress (i.e., for this example, crack sealing is shown as effective for minor fatigue cracking; however, if fatigue, linear cracking, and moisture damage are all present at the same time, crack sealing may or may not be a feasible option). HMA

Surface Treatments Purpose
Typically used to: Seal cracks Waterproof surface Improve friction Improve rideability Rejuvenate surface Surface treatments can be described as “thin” treatments applied to the entire HMA surface. Surface treatments are applied to HMA pavements for a number of reasons. Some of the more common application reasons are listed here: Seal cracks (especially if the amount of cracking has become too great to cost effectively seal individual cracks). Waterproof the surface. Improve friction. Improve rideability. Rejuvenate surface. HMA

Surface Treatments Types
Fog seal Slurry seal Microsurfacing Chip seal Scrub seal Ultrathin friction course Others? This slide lists some of the specific surface treatment techniques commonly used on HMA-surfaced pavements. Each of these treatments will be discussed in more detail in the following slides. Multiple chip seals (cape seals). Rejuvenating seals. HMA

Fog Seal Description Purpose
Light application of diluted, slow-setting asphalt emulsion without aggregate cover Purpose Fog seals are defined as a light application of a diluted asphalt emulsion (typically 8:1 or 9:1 mixture) placed primarily to seal the pavement, prevent raveling, enrich hardened asphalt, or provide delineation with the shoulder. Fog seals are most effective on pavements in relatively good condition (i.e., little or no cracking or raveling). Fog seals have been found to last an average of 1 to 2 years, and repeated applications are expected to provide improved effectiveness. However, no formal studies have been conducted to evaluate the effect of fog seals on prolonging pavement life. Fog seals most commonly consist of a slow-setting emulsion that takes time to “break.” Because of the required time to break, the pavement must typically be closed for approximately 2 hours after placement. Therefore, fog seals may not be appropriate for pavements in high traffic urban areas. In addition, fog seals have the potential for reduced surface friction if excess asphalt is an advertently applied to the pavement, therefore, they are not recommended on high speed roadways. Seal pavement Inhibit raveling Enrich hardened/oxidized asphalt Provide delineation with shoulder HMA

Fog Seal Feasibility Distress Type Fatigue Cracking
Extent of Problem Distress Type Minor Major Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Feasible Not Appropriate Fog seals reduce the future potential of moisture damage by reducing moisture infiltration. NOTE: define the difference between stripping- and subgrade softening-related moisture damage. A stripping pavement should NOT be sealed as this will accelerate the distress. HMA

Fog Seal Effectiveness Distress Type Fatigue Cracking
Extent of Problem Distress Type Minor Major Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Effective Marginal No Impact HMA

Slurry Seal Description Purpose
Mixture of well-graded aggregate and slow setting asphalt emulsion Purpose Seal surface cracks Correct raveling/oxidation Fill minor surface irregularities and restore friction A slurry seal is a mixture of well-graded aggregate (fine sand and mineral filler) and diluted asphalt emulsion that is spread over the entire pavement surface with either a squeegee or spreader box attached to the back of a truck. (NCHRP 223) There are three types of slurry seals as defined by the International Slurry Surfacing Association (ISSA), and these are differentiated based on traffic volume served and aggregate gradation (aggregate size). Type I is used to seal surface cracks on low-volume roadways (6 mm [1/4 in] aggregate). Type II (the most common) is used to correct raveling and oxidation on roadways with moderate to heavy traffic levels (8 mm [5/16] aggregate). Type III is used to fill minor surface irregularities and restore surface friction (10 mm [3/8 in] aggregate). Slurry seals are appropriate for use when the primary deterioration is related to excessive oxidation and hardening of the existing asphalt. Aggregates must be clean, angular, durable, well-graded, and uniform (prefer 100 percent crushed). Slurry seals are considered to have a nominal life of 3 to 5 years. HMA

Slurry Seal Feasibility Distress Type Fatigue Cracking
Extent of Problem Distress Type Minor Major Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Feasible Not Appropriate Reduction in moisture damage. Addresses friction loss (all levels). HMA

Slurry Seal Effectiveness Distress Type Fatigue Cracking

Microsurfacing Description Purpose
Mixture of high-quality aggregates and polymer-modified emulsion binder Purpose Microsurfacing is defined as a mixture of high quality aggregate and a polymer-modified emulsion binder. This technique is primarily used to correct or inhibit raveling and oxidation of the pavement surface, however, it is also effective in improving surface friction, sealing the pavement surface, and filling minor surface irregularities and wheel ruts (up to 32 mm [1.25 in] deep in a single pass). There are two generally accepted aggregate gradations; the choice depends on the type of application. The use of a CSS-1hp binder is common (the “CSS” indicates a catatonic, slow setting emulsion, the “1” its relative viscosity [a “-2” is more viscous than a “1”], the “h” meaning a harder grade of base asphalt was used in the production of the emulsion, and the “p” meaning polymer-modified). Other interesting facts: Microsurfacing has successfully been used on both low and high volume roadways. Microsurfacing has been found to perform well for 4 to 7 years, depending on the condition of the existing pavement. Ruts up to 50 mm (2 in) have been successfully filled, with recurrence of rutting within 3 to 5 years. Initial friction numbers range from the mid 40s to upper 50s (where higher friction numbers represent greater friction—highway agencies typically require improved surface friction when the values dip below about 35). When underlying cracks are not working, microsurfacing delays the development of those cracks in the new surface (reflective cracking). With rutting, you have to figure out the type of rutting and where the deformation is occurring. “Stable” ruts would be good candidates for preventive maintenance; “unstable” ruts would not be good candidates. Inhibit raveling and surface oxidation Improve surface friction Fill ruts/minor surface irregularities Seal pavement surface HMA

Microsurfacing Feasibility Distress Type Fatigue Cracking
Extent of Problem Distress Type Minor Major Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Feasible Not Appropriate HMA

Microsurfacing Effectiveness Distress Type Fatigue Cracking

Chip Seal Description Purpose
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 A chip seal (also referred to by other names including surface treatments, bituminous surface treatments, surface dressings, and seal coats) is defined as an application of asphalt (commonly an asphalt emulsion) directly on the pavement followed by an application of aggregate chips. The resulting treatment is then rolled to embed the chips in the binder. Chip seals are typically used to seal the pavement surface and improve surface friction. There is a complete family of treatments that fall into the “chip seal” category. Rubberized asphalt chip seals are commonly used in conjunction with HMA overlays to retard reflection cracking. Sand seals are used to enrich a dry, oxidized surface and to prevent the intrusion of moisture and air. Sandwich seals consist of large aggregate, spray of asphalt emulsion, and application of smaller aggregate. They are used to seal the surface and improve skid resistance. Cape seals are a chip seal covered with a slurry seal and are used to provide a dense waterproof surface with improved skid resistance. There are also multiple applications of chip seals, in which two different sized chips are placed in a built-up application. HMA

Chip Seal Feasibility Distress Type Fatigue Cracking
Extent of Problem Distress Type Minor Major Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Feasible Not Appropriate If you have a “flushing” pavement, a chip seal may be all right. A chip seal would not be appropriate on a “bleeding” pavement. HMA

Chip Seal Effectiveness Distress Type Fatigue Cracking

Scrub Seal Description Purpose
Application of sand or small-sized aggregate on broomed layer of polymer-modified asphalt This slide is animated in that is contains three different scrub seal-related photos. 1) picture of brooms, 2) process, 3) finished scrub seal. A scrub seal consists of a layer of polymer-modified asphalt that is broomed into the voids and cracks of the pavement, followed by the application of sand or small-sized aggregate. The mixture is then broomed again and rolled with a pneumatic-tired roller. Scrub seals have been used since the 1950s, with California and Arizona being some of the pioneers in its use. Only recently have other states started to look at scrub seals as a viable maintenance treatment. Scrub seals are intended to rejuvenate the asphalt surface and to fill voids and surface cracks. Other interesting facts: Scrub seals are showing good performance on lower volume roads (less than 7,500 ADT). Generally easy to apply and relatively inexpensive. They have been used extensively in California and Arizona, and recently seeing more use in Missouri. Some concerns regarding low friction levels on some roadways. A disadvantage is that is requires some special equipment. 2 - 3 hour cure time. Purpose Fill and seal small cracks and voids Enrich hardened/oxidized asphalt Preparation for another treatment HMA

Scrub Seal Feasibility Distress Type Fatigue Cracking
Extent of Problem Distress Type Minor Major Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Feasible Not Appropriate HMA

Scrub Seal Effectiveness Distress Type Fatigue Cracking

Ultrathin Friction Course
Description Gap-graded, polymer-modified HMA placed on a heavy, polymer-modified emulsified asphalt tack coat An ultrathin friction course (also called a paver placed seal) consists of a gap-graded, polymer-modified HMA (thicknesses of 10 to 20 mm [0.4 to 0.8 in]) placed on a heavy, polymer-modified emulsified tack coat. It is an alternative to chip seals, microsurfacing, or thin HMA overlays as it effectively addresses minor surface distresses and increases surface friction. Other interesting facts: This technique is widely used in France and was recently introduced in the United States. In the United States, this product is marketed under the NOVACHIP® name. The short-term performance of ultrathin friction course projects has been promising. Texas and Pennsylvania are two states monitoring the performance of these installations, and they report excellent performance after 3 years. The installation cost for ultrathin friction courses is about $3 per square meter ($2.50 per square yard), about 50 percent more than a thin dense-graded HMA overlay. Purpose Increase surface friction Address surface distress Reduce noise HMA

Feasibility Extent of Problem Distress Type Minor Major Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Feasible Not Appropriate HMA

Effectiveness Extent of Problem Distress Type Minor Major Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Effective Marginal No Impact HMA

Recycling Treatments Purpose
Typically used to: Rework HMA to a depth of 50 to 100 mm (2 to 4 inches) Correct surface distresses Improve profile, crown, and slope The recycling treatments referenced to here can be generally described as treatments that “rework” or “rejuvenate” the upper portion of an HMA pavement surface. Some of the more common reasons for applying a recycling treatment are listed here: The primary purpose of recycling is to address distresses that are limited to the upper portion of the pavement. This reworking of the upper portion of the surface layer addresses surface distresses such as minor cracking, corrugations, bleeding, low surface friction, and rutting. Improve profile, crown, and slope. For those who challenge whether recycling is actually PM, point out that we are trying to present a whole range of treatments and that there are times when it might be appropriate. A new pavement surface that is stripping susceptible, for example, before it starts stripping. HMA

Recycling Treatments Types
Cold In-Place Recycling Hot In-Place Recycling Recycling treatments can be divided into two classes based on construction method: cold in-place recycling and hot in-place recycling. Each of these types will be briefly discussed in the following slides. HMA

Cold In-Place Recycling
Description Milling, rejuvenating, and replacement of the top portion of the HMA surface (performed without heat) Cold in-place recycling (CIR) is a process in which the top portion of the HMA surface is milled, rejuvenated, and reused on the existing pavement. It is performed without heat and is generally used as a base course for a new wearing surface. The reclaimed material is mixed with a new binder (usually a SS or MS emulsion) and additives to help restore its original properties, and may also be mixed with some virgin aggregate. The resulting mixture is then placed back on the pavement as a base course, with a new wearing course (HMA or chip seal) placed later. CIR may be limited to the top few inches of the existing pavement, or it may include the full depth of the asphalt layer with or without some underlying base course materials. However, the milling depth is limited to 50 to 100 mm (2 to 4 inches) to be considered as a preventive maintenance technique. The primary purpose of CIR is to correct surface distresses (raveling, corrugation, rutting, bleeding, friction loss, and minor cracking) that are limited to the upper portion of the pavement. The process, however, can also be used to restore profile, crown, and cross-slope. Distresses attributed to subgrade or base failures cannot be remedied by CIR. Purpose Rework HMA to depth of 50 to 100 mm Correct surface distresses Improve profile, crown, and cross-slope HMA

Hot In-Place Recycling
Description Milling, rejuvenating, and replacement of the top portion of the HMA surface (performed with heat) Hot in-place recycling (HIR) is a process in which the top portion of the HMA surface (25 to 50 mm [1 to 2 in]) is heated, mixed with a recycling agent (and perhaps virgin materials), and reused on the existing pavement. Commonly, 25% new material is used (some agencies are using 30 to 35% new material). The primary purpose of HIR is to correct surface distresses such as raveling, corrugation, rutting, bleeding, friction loss, and minor cracking. Distresses attributed to subgrade or base failures cannot be remedied by HIR. HIR can also be used to restore profile, crown, and cross-slope. There are three types of HIR techniques available: Heater-scarification is the earliest form of HIR and is a simple process in which the surface of the pavement is heated, scarified with a set of scarifying teeth, mixed with a recycling agent, and then leveled and compacted. The repaving technique heats the existing pavement and mills or scarifies it to a depth of 19 to 25 mm [0.75 to 1 in], and then mixes in a recycling agent. This recycled material is then placed as a leveling course and is then followed with a hot mix wearing surface (either immediately or at some later time). The remixing technique removes a portion of the existing pavement and then mixes it with controlled amounts of virgin mix and/or rejuvenating agents in an on-board pugmill. The resultant mixture is then placed as the new surface course. Purpose Rework HMA to depth of 25 to 50 mm Correct surface distresses Improve profile, crown, and cross-slope HMA

Cold and Hot In-Place Recycling
Feasibility Extent of Problem Distress Type Minor Major Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Feasible Not Appropriate Recycling addresses “surface” distress. Deeper problems are not corrected. HMA

Cold and Hot In-Place Recycling

Milling with Thin HMA Overlay
Description Application of a new HMA wearing course after milling of the top portion of the HMA surface The combination of cold milling and the application of a thin HMA overlay is a viable option for improving rideability and surface friction, reducing hydroplaning and tire splash (using an open graded friction course), and improving the profile, crown, and cross slope of an existing pavement. The process begins with the removal of a portion of the existing pavement surface (using carbide-tipped cutting bits) to a specified depth (typically about 19 to 38 mm [0.75 to 1.50 in]). Cold milling is generally not suitable for pavements with significant deterioration or distress. Thin HMA overlays are plant-mixed combinations of asphalt cement and aggregate. The thickness typically varies from 19 to 38 mm (0.75 to 1.50 in). Little additional structure is added to the pavement, so it must be in relatively good condition to be a candidate for a thin HMA overlay. The following three different types of thin HMA overlays are available: Conventional dense-graded—Aggregate is uniformly distributed throughout the full range of sieve sizes. Open graded friction course (OGFC)—Aggregate particles are uniformly graded (i.e., or predominantly a single size). Additional benefits provided by an OGFC are reductions in hydroplaning and tire splash and spray. Stone matrix asphalt (SMA)—Aggregates are gap-graded, meaning that they contain coarse fractions and fine aggregate sizes, but no medium aggregate sizes. SMA also uses a high percentage of mineral filler (8 to 10 percent), and stabilizing additives such as fibers and polymers are added to control segregation and draindown. Purpose OGFC reduce hydroplaning and tire splash Improve rideability and surface friction Improve profile, crown, and cross-slope HMA

Feasibility Extent of Problem Distress Type Minor Major Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving Feasible Not Appropriate HMA

Maintenance of Drainage Features
Description Any activity that will improve the drainability of a pavement section Purpose Minimize time to remove infiltrated or surface water Maintenance of drainage features involves the conducting of any activity that will improve the drainability of a pavement section including activities such as: Clear debris from outlets and culverts. Inspect edge drain pipes. Flush and rod edge drain system. Clean ditches and re-establish grades. Restore cross slopes. Drainage enhancements or corrections may last from a few months to several years depending on conditions. Periodic inspections are required throughout the life of the pavement. Costs are dependent on the activity being performed. Impact of positive drainage on pavement performance currently being studied. Recommended Use Strongly recommended on all HMA pavements HMA

PM Techniques for PCC-Surfaced Pavements

Common PM Techniques for PCC-Surfaced Pavements
Joint /crack sealing Diamond grinding Diamond grooving Undersealing Load transfer restoration Maintenance of drainage features Here are the preventive maintenance techniques typically applied to PCC-surfaced pavements. Note that the maintenance of drainage features is one technique that is common to both HMA and PCC pavement surface types. PCC

Joint/Crack Sealing Description Purpose
Application of a sealant material in concrete pavement joints and cracks This slide is animated in that is contains three different joint/crack sealing photos. 1) picture of joint refacing, 2) crack sawing, 3) installation of sealant. Joint and crack sealing (and resealing) are used to prevent water and debris (incompressibles) from entering joints and cracks in a PCC pavement. Limiting water infiltration protects the underlying pavement layers and reduces the detrimental effects of freeze thaw cycling; therefore, reducing the probability of pumping, faulting, and corner breaks. Preventing the intrusion of incompressibles into joints or cracks limits the possibility of spalling and blow-ups. For PCC pavements, the most common sealant materials are rubberized asphalt and silicone. There is an ongoing study (SHRP 106) that is looking at different types of sealant reservoirs and sealant types. Sealing of PCC-HMA shoulder joint is critical as 75 – 80% of water infiltration enters through this joint. Purpose Minimize moisture infiltration Prevent intrusion of incompressibles PCC

Joint/Crack Sealing Feasibility Distress Type Linear Cracking
Extent of Problem Distress Type Minor Major Linear Cracking Corner Breaks Transverse Joint Faulting Joint Spalling D-Cracking Pumping Roughness Friction Loss Surface Distress Feasible Not Appropriate HMA

Joint/Crack Sealing Effectiveness Distress Type Linear Cracking
Extent of Problem Distress Type Minor Major Linear Cracking Corner Breaks Transverse Joint Faulting Joint Spalling D-Cracking Pumping Roughness Friction Loss Surface Distress Effective Marginal No Impact Joint spalling—we are keeping incompressibles out of the joint. Sealing keeps water out which could potentially lead to pumping, faulting, and crack deterioration. HMA

Diamond Grinding Description Purpose
Removal of a thin layer of PCC using stacked diamond tipped cutting blades Purpose This slide is animated in that is contains three different diamond grinding photos. 1) grinding process, 2) grinding head, 3) close-up of final ground surface. Diamond grinding is the process of removing a thin layer of PCC (typically about 6.4 mm [0.25 in]) such that faulting is removed, smoothness is improved, and surface friction is restored. Diamond grinding is typically applied over an entire project. Most stacked diamond heads are approximately 0.9 m (3 ft) in width. For diamond grinding, the distance between diamond tipped blades (“land area”) depends on the hardness of the aggregate; the idea is that the land area will break off under traffic. Typically, the land area is 2.0 mm (0.08 in) for hard aggregate and 2.8 mm (0.11 in) for soft aggregate. Remove faulting Improve surface rideability Improve surface friction PCC

Diamond Grinding Feasibility Distress Type Linear Cracking

Diamond Grinding Effectiveness Distress Type Linear Cracking
Extent of Problem Distress Type Minor Major Linear Cracking Corner Breaks Transverse Joint Faulting Joint Spalling D-Cracking Pumping Roughness Friction Loss Surface Distress Effective Marginal No Impact Only effective at correcting very minor spalling. If you have 6 to 10 mm (0.25 to in) faulting, you may be outside of preventive maintenance. HMA

Diamond Grooving Description Purpose
Creation of narrow grooves in the PCC surface using diamond tipped cutting blades (localized areas) This slide is animated in that is contains two different diamond grooving photos. 1) longitudinal grooving, 2) transverse grooving. Diamond grooving is the process of cutting narrow, discrete grooves in the PCC surface to reduce hydroplaning and wet weather accidents. Unlike diamond grinding, diamond grooving is typically applied localized areas of a project where wet-weather accidents have historically been a problem (e.g., curves and intersections). Grooving is most commonly performed longitudinally due to ease of construction. Diamond grooving produces grooves that are more widely spaced than those cut for diamond grinding. For diamond grooving, grooves are typically cut approximately 19 mm (0.75 in) on center. Purpose Reduce hydroplaning and wet weather accidents PCC

Diamond Grooving Feasibility Distress Type Linear Cracking

Diamond Grooving Effectiveness Distress Type Linear Cracking
Extent of Problem Distress Type Minor Major Linear Cracking Corner Breaks Transverse Joint Faulting Joint Spalling D-Cracking Pumping Roughness Friction Loss Surface Distress Effective Marginal No Impact HMA

Undersealing Description Purpose
Pressure insertion of flowable material beneath the PCC slab Purpose Fill underlying voids (not to raise slab) Reduce pavement deflections Minimize pumping and faulting Undersealing (sometimes called “subsealing,” “pressure grouting,” or “slab stabilization”) is the pressure insertion of flowable grout material beneath a PCC slab to restore support to areas where pumping or loss of support have occurred. Typically, undersealing is used beneath transverse joints and deteriorated cracks. The purpose of undersealing is to fill any underlying voids, reduce pavement deflections, and therefore, minimize pumping and faulting. Undersealing is NOT to be used to lift the slab. The material is usually a cement-flyash grout that is inserted under pressure through a hole drilled in the concrete slab. PCC

Undersealing Feasibility Distress Type Linear Cracking Corner Breaks

Undersealing Effectiveness Distress Type Linear Cracking Corner Breaks
Extent of Problem Distress Type Minor Major Linear Cracking Corner Breaks Transverse Joint Faulting Joint Spalling D-Cracking Pumping Roughness Friction Loss Surface Distress Effective Marginal No Impact HMA

Load-Transfer Restoration
Description Placement of load transfer devices across joints or cracks in an existing pavement Load-transfer restoration (also known as retrofitted load transfer) is defined as the placement of load transfer devices (typically dowel bars) across joints or cracks in an existing PCC pavement to restore load transfer. Transverse joints originally constructed without dowel bars are good candidates for this operation. The purpose is to provide reliable load transfer across the joints (and/or cracks) so that pumping, faulting, and corner breaks are reduced or eliminated. Purpose Provide reliable load transfer Reduce or eliminate pumping, faulting, and corner breaks (reducing deflections) PCC

Feasibility Extent of Problem Distress Type Minor Major Linear Cracking Corner Breaks Transverse Joint Faulting Joint Spalling D-Cracking Pumping Roughness Friction Loss Surface Distress Feasible Not Appropriate HMA

Effectiveness Extent of Problem Distress Type Minor Major Linear Cracking Corner Breaks Transverse Joint Faulting Joint Spalling D-Cracking Pumping Roughness Friction Loss Surface Distress Effective Marginal No Impact HMA

Maintenance of Drainage Features
Description Any activity that will improve the drainability of a pavement section Purpose Minimize time to remove infiltrated or surface water Maintenance of drainage features involves the conducting of any activity that will improve the drainability of a pavement section including activities such as: Install and maintain reference markers Clear debris from outlets and culverts Inspect edge drain pipes Flush and rod edge drain system Clean ditches and re-establish grades Restore cross slopes Recommended Use Strongly recommended on all PCC pavements PCC

Do you use any techniques other than those listed?
Other PM Techniques? Do you use any techniques other than those listed? Does your agency use any maintenance techniques that were not listed on the previous slides? If so, what are they? Do you think they are applicable as preventive maintenance techniques? How are they different from the previously listed techniques? In what types of situations have they been used? How well have they performed? Ongoing research continues in the area of developing new maintenance methods and materials that may be appropriate as future preventive maintenance techniques. (Have the participants discuss other potentially applicable treatments or other applications that are not listed. This is a good opportunity to encourage participation from the group.)

PM Techniques for Shoulders?
What’s different? What’s the same? HMA shoulders will deteriorate differently from the mainline pavement. Are they ever put on a separate maintenance schedule? What other types of bituminous surfaced shoulders are used? Is their maintenance different? For PCC shoulders, the maintenance should really not be different. Faulting, ride, and other performance measures are not as important.

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

Preventive Maintenance Treatments

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