Influence of Pavement Condition on Project Selection Session 3 Influence of Pavement Condition on Project Selection This presentation describes key distress types in both flexible and rigid pavements and examines the suitability of the distresses to preventive maintenance treatments. For example, what are the types of distresses that can be corrected by preventive maintenance treatments? Are these distresses all low severity? Is a pavement still be a candidate for preventive maintenance if medium-severity distresses are visible? Is there a level below low severity that could be identified? Should such treatments be applied to pavements that have not yet developed any distress? Another key topic covered in the presentation is the way that the distresses are identified. Do typical condition survey methods provide information relevant for preventive maintenance programs? How do preventive maintenance survey needs differ from pavement management needs, or are they the same? It is likely that in addition to pavement condition, the engineer must have additional knowledge about the pavement, including construction and performance data on the pavement. From where does this information come? Some may be obtained through records review or perhaps a pavement management database. However, one of the most important sources of information on pavement condition and the performance of maintenance and rehabilitation treatments is from maintenance/field personnel. In addition to taking advantage of their insights, interaction with this group helps to ensure buy-in of the pavement preservation concept.

Learning Objectives Upon completion of this module, you will be able to: Define pavement condition and describe typical pavement survey types Identify common HMA and PCC distress types These objectives are self-explanatory. Spend a few minutes highlighting some of the key points.

Learning Objectives (continued) Describe the typical progression of deterioration for HMA and PCC pavements Describe the effect of preventive maintenance on the typical progression of pavement deterioration

Learning Objectives (continued) Describe the importance of pavement condition survey data in developing preventive maintenance guidelines

Determining if a project is a “good candidate” for PM No structural failures Minimal distress (extent and severity) Relatively young in age Few historical problems with similar projects What do you need to know to determine if a particular project is a good candidate for PM? What are the characteristics of pavements that you would consider “good” candidates for preventive maintenance? What do we need to know to make this decision? (Ask the audience for some help in determining a list of items. Some examples of pavement characteristics are shown on this slide. Possibly make a list on a white board). After a list of pavement characteristics has been determined, try and get the audience to interpret these characteristics and really focus in on what we need to know to determine if a pavement is a good candidate for PM. We really need to know two things to make an educated decision about whether or not a given project is a good candidate for preventive maintenance (i.e., we are trying to determine where the pavement is on its pavement performance curve.) We need to estimate the current “condition” of the pavement (the next slide discusses what we mean by “condition”). We need to estimate the expected “future performance” of the pavement. Estimate pavement condition and future performance!

What pavement characteristics indicate pavement condition? Visible performance indicators Functional indicators Structural indicators Non-Visible defects Environmental effects on materials Load-related damage First, let’s define what we mean when we say pavement “condition.” Typically a discussion of pavement condition is thought of what you can see on the pavement surface. But as we have indicated, what you don’t see can be more or as important in determining where the pavement is on its deterioration curve. Visible performance indicators are those functional and structural indicators that are 1) visible on the surface, and 2) measurable. Functional performance is ride and safety. Aspects of ride quality include smoothness and noise; safety includes friction, removal of standing water. What are some indicators of pavement functionality? Rough ride, wet weather accidents, standing water, noise. Ride quality, surface friction, and surface drainage. Structural performance refers to the load carrying ability of the pavement. We can look at this indirectly by measuring the pavement response to loads or by testing the overall strength of the pavement or the strength of its individual layers. We also see signs of a pavement’s structural capacity in the distresses visible at the pavement’s surface. Distress (cracking and rutting) and surface deflections. However, pavements begin to deteriorate long before they show any visible distress. That is, environmental conditions (temperature cycles and moisture infiltration) and repeated load applications cause incremental damage to pavement layers. This cumulative damage eventually results in visible pavement distress.

Estimating Future Performance Pavement Performance Indicators Preventive Maintenance Good Typical Pavement Performance Curve Pavement Condition (Functional or Structural) When we talk about estimating pavement “performance,” what we are really interested in is determining where the pavement is on its expected pavement performance curve. In general, pavements deteriorate (functionally and structurally) along some type of curve which starts at good and ends up in poor condition over time. Although the timing and rate may be different from one type of deterioration to another, the overall S-shape of the curve remains the same. To determine if a pavement is a good candidate for PM, we really need to estimate the pavement’s remaining life (time until required rehabilitation). We know there is a window of opportunity in which preventive maintenance is effective,so it is important to estimate where on the performance curve a pavement is when considering the application of PM. If it is too early or too late, we will not see the maximum benefit. Poor Time (Years)

How do you determine a pavement’s true condition? Conduct surveys Type, amount, and severity of distress/deficiencies Identify poor PM candidates Additional information / historical records Engineering judgment How do you determine a pavement’s “true condition?” That is, how do you determine where a pavement is on its performance curve. Distress Data from Surveys Look at current visible distress data. There are a lot of other types of distress that could be visible on a pavement. Examples include the following: Material-related problems (reactive aggregate or D-cracking in PCC; bleeding in asphalt)? Subgrade softening/moisture-related damage (pumping and faulting in PCC; rutting in HMA)? Traffic-related surface problems (polishing)? Do these other visible distresses help determine whether or not a pavement is a good candidate for preventive maintenance? Yes. Are pavements that contain any other distress type excluded from consideration for preventive maintenance? The answer from the audience should be “it depends?” On what does it depend? Distress type, severity, extent, estimated cause, etc. all help decide if a particular project is a good candidate for PM. The type, amount, and severity of distress/deficiencies will typically give indications of the underlying problems. Identifying deficiency causes will help exclude pavements from consideration for preventive maintenance. What if your pavement is not showing any visible distress? Is it a good candidate? Most likely “Yes.” What types of information would you need to estimate where such a pavement on its deterioration curve. Historical records (i.e. age, material quality, design, etc.) Past performance of similar pavements in a similar climate. Additional Information Other sources of information are used to develop an understanding of how a given pavement is expected to perform. Engineering Judgment Finally, there is no straight forward answer at this point. Engineering judgment must be used to determine this “window of opportunity” for preventive maintenance. It is important to note that although we don’t know the specific “indicators” for preventive maintenance, or the optimum timing, we do know what we can prevent, and how PM treatments generally influence pavement performance.

What techniques are used to assess pavement condition? Visual distress surveys Roughness surveys Friction surveys Drainage evaluation Shoulder surveys Deflection testing With these performance indicators in mind, what types of field surveys can be used to assess these performance conditions? Contrast project level with network level. In PMS, these are project level surveys, done when the network level survey has triggered potential projects. All of these survey types give useful information when deciding on whether or not to apply preventive maintenance, as well as when selecting appropriate PM techniques. Visual distress surveys give an indication of current functional and structural conditions. Type, severity, and extent of visible distress is recorded. The visible distress types give an indication of . Roughness and friction surveys are functional-related. Drainage evaluations can be helpful in preventing structural problems. Deflection testing can be used to provide information regarding the structural condition at specific points.

Interpreting Survey Results Helps identify mechanisms causing distress (i.e., functional vs. structural) Determines when PM is not an option Speaks of urgency Identifies which treatments are appropriate and which are not Affects the type of treatment chosen This slide summarizes the role that surveys play in determining appropriate preventive maintenance. Make the point that surveys actually tell what pavements can be “excluded” from PM consideration. If visible distresses are observed, the surveys can 1) tell if PM is still appropriate, 2) help determine underlying causes of visible distress, 3) determine if any current conditions can be slowed or corrected with PM treatment applications. Also, stress that if you don’t see distress, it is likely that this pavement is a good candidate for PM. PM is much more effective on pavements in good condition. This is especially important since the remainder of this session focuses on distress. You should make the point that distress is not the sole driver of preventive maintenance, however, distress surveys do give a lot of important information about the condition of a pavement section. Also stress the point that even though SHA’s are using the same treatments for “routine” and “preventive” maintenance, PM has a different focus.

Additional Information Needs Design/Construction Records Design life Structure Materials Traffic Environment Construction quality Construction temperatures The fact that this session is entitled Characterizing Pavement Condition implies that there are more aspects to this important activity than just gathering and compiling pavement distress data. This slide provides an indication of some of the additional data needs which can be obtained from existing design and construction records. When combined with compiled data from the distress survey, this information provides a sound basis for the selection of an appropriate preventive maintenance treatment.

Additional Information Needs (continued) Data from field/maintenance personnel Maintenance history Performance of similar designs/treatments Data from PMS or planning If possible, it is also useful to work directly with field (construction) staff and other preventive maintenance personnel to develop a sense of the maintenance history of various projects what treatments have performed the best. Again, this information should complement the data from the distress surveys and help provide for a better preventive maintenance treatment selection. Reviewing PMS or Planning data can help identify the most appropriate/effective schedule for the application of preventive maintenance.

Common Distress Types HMA PCC Pavement deterioration manifests itself in many forms of distress. This course addresses these distresses according to the two main types of pavement in which they are prevalent. HMA PCC

Typical HMA Pavement Distresses Fatigue cracking Block cracking Edge cracking Longitudinal cracking Reflection cracking Potholes Rutting Bleeding/flushing Raveling/weathering Lane-to-shoulder drop-off Roughness Surface friction loss Moisture damage Stripping Shoving For HMA pavements, these represent the key types of distress. For many of these forms of distress, there is a preventive maintenance action that is feasible up to a certain level of severity and/or extent. HMA

Typical Rigid Pavement Distresses Blow-ups Transverse cracking Longitudinal cracking Corner breaks Durability cracking Transverse joint faulting Joint spalling Joint seal damage Loss of fines (pumping) Friction loss Map cracking and scaling Roughness For rigid pavements, these represent the key types of distress that affect both the structural and functional performance. Some of these distresses (e.g., blow-ups and corner breaks), even at there lowest levels of severity, preclude the use of preventive maintenance treatment treatments. PCC

Progression of Pavement Deterioration In order to apply appropriate PM at the optimal timing, one must first have a good understanding of the typical progression of pavement deterioration for both HMA and PCC surfaced pavements. What must be stressed is that no matter how well-defined and well-constructed a pavement is, it will deteriorate over time as a function of repeated climatic cycles and traffic-related applications. When trying to determine appropriate PM, it is important to ask yourself “How do I expect my pavements to perform?” You should have a feel for the typical performance of a pavement in your state given a particular location (climate) and traffic. Point out that variation is great in performance due to changes in many characteristics: environment, design, construction, etc. PCC HMA

HMA Pavement Deterioration Catalysts of Deterioration Traffic Environment / Aging Material problems Water infiltration Shown here are the four general causes of deterioration in HMA pavements. HMA

Primary HMA Deterioration Initial Mechanisms of Deterioration Environment / Aging Material / Mix Load / Traffic Asphalt Hardening Various Changes Plastic Deformation Surface wear The general causes of deterioration (shown on the last slide) influence pavement performance in different ways. Traffic loadings typically lead to plastic deformation. Traffic applications (tire/pavement interaction) cause a wearing of the surface. Environmental and aging effects cause the oxidation (hardening) of the asphalt. HMA material or mix problems can lead to various different types of distress. HMA

Primary HMA Deterioration Load-Related Distresses Rutting Fatigue Cracking Plastic Deformation These are build slides that show the progression of load distresses in HMA pavements. What distresses do you see? HMA

Primary HMA Deterioration Traffic-Related Distresses Polishing Surface Wear An additional traffic-related distress involves the polishing of the surface which leads to friction loss. Bleeding can also lead to friction loss. Friction Loss HMA

Primary HMA Deterioration Environment/Aging-Related Distresses Block Cracking Raveling/Weathering Asphalt Hardening This is also a build slide. HMA

Primary HMA Deterioration Material/Mix-Related Distresses Material Problems Bleeding can also lead to loss of friction. Bleeding/Flushing Friction Loss HMA

Secondary HMA Deterioration Influence of Moisture Infiltration Cracks + Moisture Infiltration Deteriorated Cracks Breakdown of Existing Cracks This build slide shows the progression of deterioration from moisture infiltration. One cause of moisture infiltration into existing cracks causes the breakdown of existing cracks. This leads to: Increased roughness. Allows more water to enter pavement. HMA

Secondary HMA Deterioration Influence of Moisture Infiltration Cracks + Moisture Infiltration Potholes Loss of Fines (Pumping) Lane-to-Shoulder Drop-off Edge Cracking Subgrade Softening HMA

PCC Pavement Deterioration Catalysts of Deterioration Load/Traffic Environment and material problems Poor construction quality Water infiltration Incompressibles in joints Here are general categories of PCC pavement deterioration. We will look at each one in more detail. PCC

PCC Pavement Deterioration Initial Mechanisms of Deterioration Environment / Materials Construction Quality Load / Traffic Joint Problems Joint and Surface Problems Slab Fatigue Surface Wear PCC

PCC Pavement Deterioration Load-Related Distresses Loads Transverse Cracking Slab Fatigue The typical load-related distress on PCC pavements is transverse fatigue cracking. PCC

PCC Pavement Deterioration Traffic-Related Distresses Polishing Surface Wear Polishing and/or rutting be caused by studded tire and chain wear in some states. Friction Loss PCC

PCC Pavement Deterioration Env./Material-Related Distresses Environment/ Materials Durability (“D”) Cracking Joint Seal Damage Joint Problems PCC

PCC Pavement Deterioration Construction-Related Distresses Poor Construction Quality Longitudinal Cracking Map Cracking Scaling Joint and Surface Problems PCC

PCC Pavement Deterioration Influence of Moisture Infiltration Cracks + Moisture Infiltration Deteriorated Cracks Breakdown of Existing Cracks PCC

PCC Pavement Deterioration Influence of Moisture Infiltration Cracks/Joints + Moisture Infiltration Loss of Fines (Pumping) Corner Breaks Transverse Joint Faulting Subgrade Softening PCC

PCC Pavement Deterioration Influence of Incompressibles Cracks/Joints + Incompressible Material Joint Spalling Blow-Ups PCC

Impact of Preventive Maintenance on Pavement Deterioration Progression What do you think the implications of PM are on pavement performance? We have looked at load-, environmental-, material-, and construction-related problems. Are all of these preventable with PM? Obviously not. It depends on the mechanism. Preventive maintenance is not appropriate for all discussed distress mechanisms.

How can the application of preventive maintenance treatments influence the typical pavement deterioration progression?

What are the overall objectives of effective preventive maintenance? Preserve investment (Structural considerations) Maintain high level of service (LOS) In general terms, preventive maintenance can be seen to have two different overall objectives: Preserve the investment (minimize structural failures and extend the structural life of the pavement), and Maintain a high level of service for the pavement surface (maintain acceptable smoothness and surface friction). A secondary objective of maintaining a high LOS is improving public perception. Smoother roads with less visible distress result in a better image of the managing agency. Are there other objectives? Another way of looking at these objectives is how they influence costs. Why are we interested in “preserving the investment?” Because we are interested in minimizing the Agency costs associated with maintaining an acceptable level of service. Why are we interested in “maintaining a high level of service for the pavement surface?” Maintaining the minimum level of service not only focuses on minimizing the Agency costs, it is also important to provide a smooth and safe roadway that in turn minimizes the costs incurred by the User (these include vehicle operating costs [VOC], accident costs, and discomfort costs). We will now briefly look at how preventive maintenance directly accomplishes these two goals. (Functional considerations) Other objectives?

How is PM used to preserve the investment? Keep water out! Reduce infiltration Maintain drainage Reduce debris infiltration into joints or cracks Slow aging effects of bituminous pavements Minimize dynamic loads Based on all of the types of preventive maintenance techniques that have been presented in this module, what types of things does preventive maintenance specifically do to “preserve the investment?” Many of the preventive maintenance activities are applied to “keep water out.” Reducing the potential for water infiltration and maintaining well performing drainage will help protect the underlying layers from being softened or washed away. Reducing water infiltration also reduces that effects of freezing and thawing in colder climates. The same preventive maintenance techniques that keep water out, also keep incompressible debris from entering joints or cracks. Keeping incompressibles out of joints and cracks greatly reduces the potential for HMA and PCC crack deterioration, PCC joint spalling, and blow-ups in PCC pavements. Surface treatments can be used to slow asphalt aging/hardening on HMA pavements. The rougher the pavement surface, the higher the impact of dynamic vehicle loadings.

How is PM used to maintain an acceptable LOS for the pavement surface? Maintain good rideability Maintain good surface friction Minimize additional dangerous surface characteristics Edge drop-off Rutting (hydroplaning) Based on all of the types of preventive maintenance techniques that have been presented in this module, what types of things does preventive maintenance specifically do to “maintain an acceptable level of service for the pavement surface?” Many of the preventive maintenance activities are applied to “maintain good rideability.” Pavement smoothness is probably the pavement characteristic most noticed by the traveling public. Other preventive maintenance activities are applied specifically to improve the pavement surface friction. Maintaining good surface friction improves roadway safety (mainly by reducing hydroplaning potential, and therefore, wet-weather accidents).

Specific Results of Preventive Maintenance Treatment Applications Prevent or slow some distresses from occurring Correct some (mostly minor) surface deterioration Specifically, PM treatments have two different uses: Prevent or slow many distresses from ever occurring (blow-ups, sealed joints and cracks prevent softening of subgrade due to water infiltration). Correct some surface distress when applied (surface friction restoration, microsurfacing to fill ruts). Most surface distress addressed with PM is minor. Make the point that PM does not address all types and severities of surface distress.

Pavement Problems Prevented or Slowed with PM Treatments HMA Problems PCC Problems Loss of fines (pumping) Crack deterioration Block cracking Edge cracking Potholes Weathering/raveling Roughness Corner breaks Blow-ups Joint spalling Joint faulting What other types of pavement problems can be prevented or slowed with PM treatments?

Common Pavement Problems Corrected with PM Treatments HMA Problems PCC Problems Non subgrade softening rutting Raveling Bleeding/flushing Surface friction loss Roughness Joint seal damage Map cracking and scaling What other types of pavement problems can be corrected with PM treatments? Make the point that rutting is correctable under preventive maintenance only if 1) it is relatively minor, and 2) its development is not due to subgrade softening. Note: we are not talking about structural problems in this table.

Importance of Distress when Selecting PM Candidates and Appropriate PM Treatments

Significance of Distress Feasibility of PM treatments Selecting “good candidates” for PM Selecting appropriate PM treatments What you don’t see may be as important as what you do see! Pavement condition data is not used in the traditional reactive methods used for determining pavement rehabilitation. What makes distress such an important consideration in a preventive maintenance program? Like the selection of other types of maintenance and rehabilitation, distress offers a basis for the defining the feasibility of various candidate preventive maintenance treatments. If an agency is pursuing a preventive maintenance program, observations of distress will provide a sound basis for identifying the pavements which are the best candidates for preventive maintenance. When it comes to identifying appropriate preventive maintenance treatments for a given project or identifying candidate projects for pavement maintenance, pavement distress is an essential consideration. Furthermore, limitations on the applications of preventive maintenance make what you don’t see as important as what you do. A survey of current distress is the best estimate of where your pavement is in the typical expected pavement deterioration process. We are trying to get to the point where we have “objective” criteria that tells you when it is 1) too late or 2) too early for preventive maintenance. The next cutting edge research is to detect these indicators prior to seeing distress (i.e., NDT methods). What do you measure to obtain such answers? We currently don’t have a good handle on this question. However, we DO know “pavement distress progression,” we DO know “pavement distress,” and we DO know when it is too late to apply PM.

When should preventive maintenance be applied? Good Defer Action Reconstruction Pavement Condition (Functional or Structural) Rehabilitation Going back to the earlier slide used to illustrate the concept of pavement deterioration and performance, it is easy to super-impose the regions of the deterioration curve where the different categories of maintenance, rehabilitation, and reconstruction would be applicable. As is indicated, preventive maintenance is an activity that is exercised early in the pavement life when the overall condition of the pavement is at relatively high level. Given this, it should be clear that the distress surveys required for a preventive maintenance program must take place early in the pavement life (say, 3 to 6 years for flexible pavements and 4 to 8 years for rigid pavements). It is important to “learn from your pavements” as these ranges will differ for each group of pavements with similar characteristics (pavement type, materials, environment, construction quality, traffic, etc.) In addition, to determining the appropriate timing of first preventive maintenance application, one also must determine the most appropriate frequency for additional applications. Point out that we currently don’t know when the window for preventive maintenance ends. It is most likely different for every combination of pavement type, climatic conditions, materials, subgrade support, etc. Poor Time (Years)

When should preventive maintenance be applied? Good Pavement Condition (Functional or Structural) Make point that if you start PM when pavement is in good condition, you can continue to maintain a high LOS with repeated applications of relatively inexpensive PM treatments. Poor Time (Years)

When is it too late for preventive maintenance? HMA Problems PCC Problems Potholes Severely deteriorated cracks Delamination Unstable rutting Others? Blow-ups Corner breaks See if the class can identify that signs of structural deterioration are indicators that preventive maintenance is not appropriate.

Maximum Allowable Distresses HMA Pavements Extent of Problem Distress Type Minor Major Fatigue Cracking Linear & Block Cracking “Stable” Rutting Raveling Flushing/Bleeding Roughness Friction Loss Moisture Damage Shoving This bar chart shows general guidelines for the maximum state of distress (in terms of extent and severity) that is allowable in a flexible pavement if it is to be considered a candidate for preventive maintenance. The term “extent” is meant to incorporate both severity and amount. More specific guidelines will be presented (by treatment) in session 4.

Maximum Allowable Distresses PCC Pavements Extent of Problem Distress Type Minor Major Linear Cracking Corner Breaks Trans. Joint Faulting Joint Spalling D-Cracking Pumping Roughness Friction Loss Surface Distress This bar chart shows general guidelines for the the maximum state of distress (in terms of extent and severity) that is allowable in a PCC pavement if it is to be considered a candidate for preventive maintenance. The term “extent” is meant to incorporate both severity and amount. More specific guidelines will be presented (by treatment) in session 4. Note: surface distress involves all mix problems that cause surface distress (i.e., map cracking, scaling, etc.)

Review of Learning Objectives Define pavement condition and describe typical pavement survey types Identify common HMA and PCC distress types

Review of Learning Objectives (continued) Describe the typical progression of deterioration for HMA and PCC pavements Describe the effect of preventive maintenance on the typical progression of pavement deterioration

Review of Learning Objectives (continued) Describe the importance of pavement condition survey data in developing preventive maintenance guidelines