Pavement Patching Practices (2014)

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24 This chapter summarizes the responses to the U.S. survey as well as follow-up interviews and communications. A total of 48 states plus the District of Columbia responded to the sur- vey, for a response rate of 96.1%. The responses are discussed and many are shown graphically in this chapter. A copy of the U.S. survey is provided in Appendix A, and the tabulated survey responses are in Appendix B. This chapter covers management and policies regarding pavement patching such as: • What distresses are suitable for patching; • What triggers patching activities; • Whether the agency has specifications, plans, or guide- lines for patching; • Any quality control and/or quality assurance (QC/QA) requirements; • When contracts are used in lieu of state workforces; • Whether patch locations and performance are monitored; • Traffic management for different patching activities and types of roadways; and • Other factors that apply to patching both pavement types. In addition, the survey addressed materials used for patch- ing asphalt and concrete pavements, equipment used, and other materials and operations topics. The survey also asked about research and resource needs. These responses are reported in later sections of this report. MANAGEMENT-RELATED SURVEY RESPONSES AND INTERVIEW FINDINGS The survey questions relevant to the management of patch- ing operations are presented here along with summaries of the survey responses. In some instances, these responses have been elaborated upon based on follow-up communications with a limited number of agencies. The first survey question asked if the respondents consider pavement patching to be a major component of their organiza- tion’s maintenance operations. In response, 43 of 49 respon- dents (85.7%) said that it was, five (10.2%) said it was not, and one (2.0%) did not answer that question (in addition to the two states that did not submit a survey response). Patching is clearly important to most states, as illustrated in Figure 13. Those respondents that did not believe it was a major compo- nent of their operations were in Arkansas, California, Florida, Massachusetts, and Nevada—most in predominantly warmer regions of the country. In an attempt to get an idea of the scale of the state patch- ing programs, the survey asked what the average annual extent of patching repairs was in their state. A variety of mea- sures was offered to make answering the question as easy as possible; these included the number or area of patches per mile, volume of patching material used, and percentage of the maintenance program. Most of the states that responded provided either a percentage of the maintenance budget or an overall cost. Arkansas reported that costs for patching amounted to only 0.10% of the state maintenance program; it is 0.5% in Nevada. Of those states that believe patch- ing is a major element, estimates of the percentage of their maintenance program ranged from 2% ($1.5 million out of a $75 million maintenance budget) in New Hampshire to as much as 40% in North Dakota and 50% in the District of Columbia. Percentages between 1% and 5% were more typi- cal. Part of the reason for such a great spread may be what costs they included in their total budget. Of 49 responses to the question “Do you have an estab- lished methodology for determining where patching is needed in your area?” 28 agencies (57.1%) said yes and 21 (42.9%) said no. In many cases, the methodology involves agency personnel knowledgeable about the roads in their area who inspect the roads and report on the need for patching; these include maintenance foremen or superintendents, pavement engineers, department patrols, and snow plow operators. States were also asked what triggers a need for patching; the responses are shown in Figure 14. All but one agency responding (48 total) indicated that visual inspections trigger a need for patching, followed closely by public complaints (43), safety issues (42), and size of a pothole (40). Less fre- quent but still significant triggers included poor ride quality (28), extent of cracking and extent of scaling or spalling (27), depth of rutting (26), roughness or raveling (24), and width of joint (20). Rumble strip deterioration was noted as a trigger for patching by one state. The most common distresses requiring patching are shown in Figure 15. Potholes are the most common distress, by far. chapter three U.S. STATE SURVEY RESPONSES

25 FIGURE 13 Do you consider patching a major activity? (Source: survey responses.) FIGURE 14 Is there a trigger that calls for patching? (Source: survey responses.) 48 43 42 40 28 27 27 26 24 20 0 5 10 15 20 25 30 35 40 45 50 Visual identification Public complaints Sudden safety problems Area or depth of pothole Poor ride quality Extent of scaling or spalling Extent of cracking Depth of rutting Roughness/ravelling Width of joint No. of respondents

26 Other significant distresses that are patched include deteriora- tion at a joint in an asphalt surface and deterioration around a previous patch. Rutting, deterioration around joints on a con- crete surface, spalling, delaminations, and joint failure are the next most common. In addition to the options given in the sur- vey, states commented that alligator cracking, frost heaves, permafrost-induced heaving and subsidence, stripping around paint striping, and top-down fatigue cracking also lead to a need for patching. The survey also asked who performs patching operations. Reactive patching is performed by state workforces in all but one of the agencies responding, as shown in Figure 16. In addition, eight states use paving contractors and four use specialty contractors for reactive patching. State workforces also do planned patching in 37 agencies, paving contractors do planned patching in 34 states, and specialty contractors in 13 states. There are a variety of approaches used to perform patching. Wisconsin reported that county highway depart- ments do all of its maintenance; in Georgia, the state con- tracts with some counties to perform maintenance on state roads. Virginia and Texas report awarding large-scale main- tenance contracts. In Nevada, all asphalt patching is done by state workforces and all planned concrete patching is done by contract. North Carolina is among the states that perform maintenance for the counties. Another question on the survey asked states to estimate how much time elapses between identifying the need to patch and completing the repair; the results are shown in 48 37 8 34 4 13 3 2 0 10 20 30 40 50 60 Reacve Planned Reacve Planned Reacve Planned Reacve Planned State Forces Paving Contractor Specialty contractor Others N o. of re sp on de nt s FIGURE 16 Who performs patching in your state? (Source: survey responses.) FIGURE 15 What are the most common distresses requiring patching? (Source: survey responses.)

27 FIGURE 17 Typically, how much time elapses between becoming aware of patching need and completion of the patch? (Source: survey responses.) 9 2 3 3 28 0 5 10 15 20 25 30 1 7 days 8 14 days 15 21 days 22 30 days > 30 days No. of respondents Figure 17. Because reactive patching often addresses a sud- denly occurring, potentially emergency situation, in most cases the reaction time is quite rapid. A reaction time of 1–7 days was reported by 42 of 46 respondents, 8–14 days by three, and 15–21 days by one. Conversely, planned patch- ing is typically accomplished in more than 30 days in 28 of the 46 states reporting. Some states (17) report accom- plishing this more rapidly, with responses ranging between 1–7 and 22–30 days. To identify which states have detailed requirements for patching, the survey asked if states had or worked from plans, specifications, or guidelines for various kinds of patching, including reactive versus planned, and temporary versus per- manent. The results (Figure 18) showed that these types of documents are used by 29 of 47 responding states for reactive patching and by one state for reactive patching by contract. Twenty-eight of 47 states reported using these documents for planned patching; however, 13 use them for planned patching by contract only. A total of 23 states reported using these stan- dards for temporary patching and 32 for permanent patching. In addition, eight states use standards for permanent patching by contract only. Along with standards for patching, the means of assess- ing quality are also important; therefore, states were asked if they have any QC/QA procedures for patching operations. Only 16 of 49 agencies reported having any QC/QA pro- cedures in place for patching (Figure 19). More often than not, these QC/QA procedures apply to concrete patches and involve testing concrete strength before opening to traffic; in one state, air content and slump were also measured. Smooth- ness or ride quality of the patch is sometimes evaluated, as are mix design and manufacturer certifications. Use of a straight FIGURE 18 Does your organization have specifications, plans or guidelines for patching? (Source: survey responses.) 0 20 40 60 Reacve Planned Temporary Permanent Yes Yes, but only for patching by contract No Number of respondents

28 FIGURE 19 Does your organization have any QC/QA procedures at the time of patch placement? (Source: survey responses.) edge to check the smoothness and flush surface of the patch was common. One state reported checking density of the patch; another requires the use of “ordinary compaction,” a standard compaction process. For asphalt patches, having an approved mix design or checking gradation were also reported quality checks. Visual inspections during and after patching are also performed. Inspection and testing are sometimes more rigorous on patching by contract than in-house patching. (See chapter five for an example of a patch inspection procedure used in one state.) States were queried to determine if they monitor the perfor- mance of patches placed in their jurisdictions. The performance of installed reactive patches is monitored routinely by 18 of 48 agencies responding and for contract work only by three additional agencies. More states monitor the performance of planned patches (24 of 49), with an additional six states moni- toring planned contracted patches, leaving nearly half the states that do not monitor the performance of patches in their jurisdic- tions (Figure 20). To track the performance of patches, it is necessary to know where they are; therefore, states were asked if they have an established method for tracking the location of patches. Nineteen of 49 states track the locations of reactive patches and 26 of 49 track planned patches (Figure 21). Most tracking is done by roadway segment or reference post (mile marker). Washington State is working with one of its regions to track patch locations using GPS. These locations are then stored in the pavement management system. Louisiana uses its maintenance management system to track locations; a planned upgrade will use handheld devices and GIS to record patching locations. Overall, the maturity of the location ref- erencing varies widely from very general (i.e., districts) to locating individual potholes (i.e., GPS). The Washington State system is described in more detail in chapter five. Another question asked if states used any form of auto- mated equipment for placing patches (see Figure 22). Some type of automated equipment is used for installing patches by 25 of the 45 agencies responding to the question and by an additional three agencies for patching by contract only. This equipment includes predominantly spray patchers and pavers. The safety of the workers and the traveling public is criti- cally important; therefore, a question on the survey asked what types of traffic management procedures were used for reactive and planned patching activities. The options given included flaggers, lane closures with cones, lane closures with arrow boards, lane closures with barriers, flashing lights and arrows on trucks and equipment, and traffic signals. The responses revealed that traffic management procedures used during patching operations vary widely depending on a num- ber of factors such as type of roadway, type of patching oper- ation (and the time it takes to install the patch), and traffic levels. Figure 23 shows the reported types of traffic control measures used; 47 agencies reported. Nearly all use flaggers for at least some patching operations, followed closely by lane closures with cones or arrow boards. Almost all agen- cies also report using flashing lights and arrows on trucks and equipment. Barriers and traffic signals are used much less frequently and more often for planned patching when they are used. One state reported that barriers are used only for planned concrete pavement patching. No agencies reported patching without traffic control, even under adverse condi- tions when throw-and-go techniques might be used. Indi- vidual agencies recounted using other types of traffic control devices including: • Automated assisted flagging devices, • A pilot car, • Work zone signing,

29 FIGURE 20 Do you monitor the performance of reactive (upper) or planned patches (lower)? (Source: survey responses.)

30 FIGURE 22 Does your organization use any form of automated equipment/machines for placing patches? (Source: survey responses.) FIGURE 21 Do you have an established method to track patch locations? (Source: survey responses.)

31 FIGURE 23 What types of traffic management procedures do you use for patching activities? (Source: survey responses.) 46 41 39 13 45 4 0 6 44 45 43 24 42 7 0 5 0 5 10 15 20 25 30 35 40 45 50 Flaggers Lane closure with cones Lane closure with arrow boards Lane closure with barriers Flashing lights and arrows on truck/equipment Traffic signals None Other(s) No. of respondents Planned Reacve • Changeable message boards and dynamic message signs, and • Police slowdowns for reactive patrols. Agencies were also asked about the typical costs for patch- ing; specifically, they were asked to report the average unit cost of patching using whatever unit of measure they apply. Many states were unable to answer the question because they do not track that data. For those states that did specify a number, there was no consistency in how that data were reported or what costs were included in the total. Some states reported material costs only; others included traffic control, and a few included labor or equipment. Because of the wide diversity of the responses, typical costs could not be derived and are not reported here. One interviewee suggested that developing a consistent reporting method and including all of the costs associated with patching would give states a better understanding of the scope of the effort and impacts of patch performance. SURVEY AND INTERVIEW FINDINGS REGARDING PATCHING ASPHALT PAVEMENTS One question on the survey inquired about what materials are used by states for patching asphalt pavements. The responses, shown in Figure 24, indicate that the states were in agreement that hot mix asphalt is the preferred material for permanent patches, being used by 47 of 49 states. Generic stockpile mix is the next most common material and is used by 37 of 49 states. Currently, warm mix is seldom used; however, this situation may change in the near future as it becomes increasingly more common and accepted, pending the results of several research projects. Polymeric materials such as epoxies are rarely used (six of 49), most likely because of the relatively high costs and lack of familiarity. It has been reported that state workforces, which do most of the patching in the DOTs, are unfamiliar with the process of mixing these materials (4). Similarly, crumb rubber mixes are rarely used (two of 49); these would typically require special equipment for heating, which is not available to most states unless they are rented or used by specialty contractors. A total of 27 states use spray injection patchers. In many of those states the equipment appears to be common, with multiple districts or maintenance units having their own equipment. For example, Indiana has one in each of the six districts, and there are reportedly more than 40 of the devices in Idaho (although not all at the DOT). The follow-up interviews revealed a con- siderable disparity in the success of spray patchers, which par- allels the findings of the literature review (see “Performance” in chapter two). Some states report using spray injection patchers very effectively. INDOT, for example, considers spray injec- tion patching to be a nearly permanent repair, especially on concrete pavements. In Georgia, on the other hand, some districts have abandoned the use of spray patchers because of problems with the materials, equipment, and patch per- formance. In terms of materials, some districts had issues with obtaining the required liquid binder and clean aggre- gates. Traveling a long way to obtain the needed materials required extra time, labor, and expense. In another district, they believed the compaction of the aggregate into the hole was insufficient and the performance of the patch was inade- quate. Problems with the equipment, including the emulsion “gumming up” the equipment and difficulties in ejecting the aggregate, were also reported. Some states seal over the tops of patches. For example, Washington State and Nebraska place chip seals over the

32 patches. Edge sealing is also recommended by some states, especially for semi-permanent patches. The decisions over which materials to use are made based on a number of factors. The two primary factors appear to be availability and cost. The responding states also have found suitable materials that generally perform in their applica- tions and they continue to use them. Many states maintain approved lists of materials that have passed testing or have worked in the past. The performance of various materials varies widely. Cli- mate obviously has an effect, with patching generally per- forming better in warmer, drier climates. Other factors play a significant role as well, particularly installation conditions and attention to detail. In some cases, lack of records of what materials were used in specific locations and inadequate fol- low-up inspections hamper judging which materials perform the most effectively. SURVEY AND INTERVIEW FINDINGS REGARDING PATCHING CONCRETE PAVEMENTS States were also asked what materials are used for patching concrete pavement. As shown in Figure 25, asphalt patch- ing material is most commonly used for patching concrete pavements as well as asphalt pavements (see Figure 24) with 41 of 49 states using it. However, many agencies consider asphalt patches on concrete to be a temporary solution until a more permanent fix can be applied. Rapid strength hydraulic cement concrete and normal hydraulic cement concrete are both used by more than half the responding states (31 and 41 31 27 20 15 9 5 1 0 5 10 15 20 25 30 35 40 45 Asphalt patching material Rapid strength hydraulic cement concrete mixtures Normal hydraulic cement mixtures (with or without… Epoxy mixtures Other rapid seng cement mixtures (e.g., calcium… Latex- or polymer modified concrete Other(s) (please specify) Gypsum based cement mixtures No. of respondents FIGURE 25 What materials are used for patching concrete pavements in your area? (Source: survey responses.) FIGURE 24 What materials are used for patching asphalt pavements in your area? (Source: survey responses.) 47 37 27 25 9 8 6 2 0 5 10 15 20 25 30 35 40 45 50 Hot asphalt mix Generic stockpile mix Spray patcher Proprietary asphalt mix Warm mix asphalt Other(s) (please specify) Polymeric materials (e.g., epoxy) Crumb rubber masc No. of respondents

33 27 out of 49, respectively). Epoxy mixtures are used much more often on concrete pavements than on asphalt pave- ments, with their use reported by 20 of 49 agencies. Next are other rapid-setting cement mixtures, such as calcium alumi- nate, calcium sulphate, and magnesium phosphate. Latex or polymer-modified concrete is used by nine of the 46 agencies responding. One state, however, reported that they stopped using latex modified concrete for patches because of prob- lems with the longevity of the patch. The use of contracts for patching concrete pavements is more common than for asphalt pavements, probably because of the skill level required to place concrete. Large patches, such as panel replacements, require specialized equipment and are therefore often done by contract. SUMMARY This survey of state agencies in the United States was com- pleted by 49 of 51 states, for a response rate of 96.1%. The responses show a significant amount of diversity in state practices, especially in terms of the management of patch- ing programs. There is increased similarity, although still significant differences, in the materials used for patching pavements.