Abstract
Concrete overlays provide a promising solution to extending pavement life, and are currently the focus of the Federal Highway Administration Every Day Counts initiative. Despite their potential benefits, concrete overlays are not commonly used in many areas of the U.S.A., including the Southeast. A survey of 19 paving contractors active in the Southeastern U.S.A. was performed to quantify recent concrete overlay projects performed by these contractors, to assess the capabilities of contractors to construct concrete overlays in this region, and to identify barriers to implementation of concrete overlays as well as opportunities to increase their use. Findings indicated contractors in the region either had extensive overlay experience or no experience constructing concrete overlays. Regardless of the experience level of the contractor, the primary barrier to implementation is that this type of work is not being let for bid. Concerns about traffic control and safety was the second most important barrier among all contractors. Experienced contractors indicated the lack of available and skilled construction personnel were also key barriers. Inexperienced contractors cited concerns about the length and duration of construction as the third most important barrier. Respondents indicated an eagerness to bid on and complete overlays. The results of this study provide insight to regional state highway agencies, municipalities, and design engineers of the capabilities of concrete pavement contractors in the region to complete concrete overlay projects. The findings will help agencies understand the capabilities and concerns of concrete paving contractors and aid in informed decisions about overlays.
Concrete overlays are characterized as a relatively thin layer of concrete that is added to an existing pavement to add structural integrity and eliminate any surface distresses that exist in the existing pavement. The use of portland cement concrete (“concrete”) can be traced back to 1901, and by the mid-1980s concrete overlays had become a standard practice in some highway agencies ( 1 ). In 1994, the National Cooperative Highway Research Program (NCHRP) Synthesis of Practice 204 indicated that concrete overlays have a relatively low maintenance service life of 20 years and many have provided up to 30–40 years of service ( 2 ). More recent surveys indicate similar or better service life for more recently constructed concrete overlays ( 3 ). Viewed by the Federal Highway Administration (FHWA) as a cost-effective maintenance and rehabilitation approach for existing pavement structures, concrete overlays are a technology included in FHWA’s Every Day Counts 6 (EDC6) initiative in the hope of increasing adoption of this approach by state highway agencies ( 4 ).
The type of concrete overlay that is most appropriate for an existing roadway depends on the condition of the pavement structure. Concrete overlays are placed over an existing pavement, either bonded or unbonded to the pavement surface. Bonded concrete overlays are suitable for existing pavements that are in good to fair structural condition, while an unbonded concrete overlay is suitable for pavements in good to partially deteriorated conditions. Selection of an overlay rehabilitation choice preserves the existing pavement structure, minimizes impact on the environment, provides a continued return on the investment of the original pavement, and typically has a lower life-cycle cost compared to asphalt overlays with an equivalent design life ( 5 – 7 ). If constructed properly, concrete overlays provide a sustainable, more resilient, and longer-lasting rehabilitated pavement section. Examples of life-cycle cost analyses for overlays are presented by Fick et al. ( 1 ).
Background
Bonded and unbonded concrete overlay approaches are used in different applications and are shown in Figure 1. Bonded concrete overlays are considered a preventative maintenance or minor rehabilitation solution for existing pavement sections, while unbonded concrete overlays are considered a minor or major rehabilitation solution for existing pavement sections ( 1 , 4 , 7 ). Bonded overlay solutions take advantage of the bonding that exists between the existing pavement and the newly placed overlay to create a monolithic pavement section. The typical thickness of a bonded concrete overlay is 4–6 in. Bonded concrete over asphalt/composite (COA-B) pavement and bonded concrete over concrete (COC-B) pavement are the bonded concrete overlay solutions. Unbonded concrete overlays are commonly used to rehabilitate existing pavements that have moderate to severe distresses. This approach considers the existing pavement to simply act as a base layer under the unbonded overlay, which serves to increase the structural capacity of the pavement structure. A bond breaker is often used to separate the existing pavement from the newly placed concrete overlay. Nonwoven geotextiles or a layer of hot mixed asphalt (HMA) or rubberized HMA are often used as bond breakers. Unbonded concrete overlays are typically between 4 and 11 in. in thickness ( 1 ). Unbonded concrete overlay of asphalt/composite pavement (COA-U) and an unbonded concrete overlay of concrete pavement (COC-U) are the unbonded approaches used.
Concrete overlay systems.
Objectives and Research Significance
Concrete overlays are currently a focus area of FHWA’s EDC6 program, with FHWA encouraging highway agencies to increase concrete overlay construction as a cost-effective, durable solution to increase the service life of roadways ( 4 ). Increasing the use of concrete overlays will require the engagement of concrete paving contractors. Currently, published information about the experience of concrete paving contractors with overlay solutions is sparse or outdated. The purpose of this study was to characterize the regional use of concrete overlay solutions in the southeastern U.S. construction market, identify the barriers as perceived by concrete paving contractors for the implementation of concrete overlay pavement rehabilitation methods on existing highways, and identify opportunities to increase the potential for concrete overlays to be selected as a pavement maintenance, rehabilitation approach, or both. Specifically, the most relevant barriers that are hindering the use of concrete overlay approaches are identified, knowledge that could be used to bridge the gap between concrete paving contractors and pavement designers and agencies. The information gathered in this study also defines the current state of implementation of concrete overlays in the Southeast U.S.A.
Potential Barriers to Concrete Overlay Implementation
Work Not Being Bid
Paving contractors can only bid and build the pavement sections that are specified, designed, and let for bid by transportation agencies and other types of owners. State highway agencies and the concrete pavement industry are constantly evolving, and as people move through the hierarchy of organizations, information is lost because of promotions and retirements, which necessitates the need for continuing education at all levels ( 8 ). There are several concrete overlay design methodologies that have been developed for the different types of overlays, and each methodology requires a different set of input variables ( 9 ). A lack of technical competency and experience with regards to the design of concrete overlay by highway agencies and pavement engineers can be a barrier to implementation, since it is the highway agencies and engineers who will specify the method of rehabilitation to be used on a highway section ( 10 ).
Concrete mixture design and proportioning for pavements has historically been performed using a heavy reliance on a stakeholder’s institutional knowledge. The specification of concrete mixtures has historically taken a prescriptive approach, which had limited input from the contractor ( 11 ). The performance engineered concrete mixture (PEM) initiative has helped bring advances in mixture design, proportioning, and technology transfer to the industry. The PEM approach encourages innovation and input from the contractor, but education at all levels is still needed ( 12 ). If the highway agencies and pavement design engineers are not comfortable with concrete overlay rehabilitation methods and the types of concrete mixtures required to support their construction, then overlays will not be specified for bid by paving contractors, hindering the implementation of this method of pavement rehabilitation.
Construction Methods
Existing Pavement Evaluation
Concrete overlay solutions are typically used when an existing pavement has some level of distress that must be corrected. To ensure that the correct concrete overlay solution is selected, a survey of the existing pavement must be completed. The evaluation will provide critical information about the type and current condition of the in-place pavement layers, the presence, type, and level of distress in those layers, the structural condition of the pavement, and the remaining life of the pavement structure ( 13 ). Findings from the evaluation will help the designer to determine if a bonded or unbonded overlay solution is the most appropriate. The evaluation process typically includes several steps, with the specifics and the significance of each step in the evaluation process varying from project to project ( 14 – 16 ). The highly recommended and optional steps in the pavement evaluation process can be summarized as in Fick et al. ( 1 ):
collecting and reviewing historical data and records;
performing a visual inspection of the site;
collecting and evaluating core samples (optional);
conducting optional analyses (project dependent);
existing pavement evaluation report.
Ensuring that bonding occurs is critical to the performance of a bonded solution. Debonding can occur if the surface of the existing pavement is not in good condition, has not been properly cleaned, or has been improperly prepared. Similarly, debonding can occur if the thermal properties of the overlay are not similar to the thermal properties of the existing pavement. Although the evaluation of the existing pavement may not be a barrier to contractors, it could be a barrier to the selection of an overlay solution by an agency if sufficient knowledge of the existing pavement is not obtained because of economic, time, or other reasons.
Paving Operations
The construction methods required to produce a high-quality concrete pavement can be a perceived barrier to implementing concrete overlay solutions. To ensure that a quality concrete pavement is placed, the paving equipment must be maintained and in good working order. During the paving operation the quality of the placed concrete should be monitored, and adjustments should be made in real time to avoid quality issues. Items that should be monitored include horizontal and vertical alignment control, edge slump, consolidation, dowel bar and tiebar placement, finishing, texturing, and curing. These items affect the overall performance of concrete pavement and should be included in the quality control (QC) plan for the project ( 13 ).
In addition, concerns about the influence of weather conditions with maintaining the quality and schedule during construction can be another perceived barrier. Proper planning for hot weather, cold weather, and rain event placement should be completed by the contractor and accounted for in the QC plan. The timing of joint sawing is another critical factor for producing a high-quality concrete pavement as a means of controlling cracking. The timing of saw cutting is dependent on the concrete properties, such as maturity and environmental conditions, such as winds, humidity, and temperature. The monitoring of when to saw cut joints should also be considered in the QC plan ( 13 ).
Concrete overlay construction will often require lane closures and a traffic control plan. The use of effective traffic control and lane closure strategies has been shown to help reduce the disruption that is created by overlay construction ( 17 ). The establishment of performance goals and measures for work zones, the use of project management software to optimize construction sequencing, and the use of intelligent transportation systems to dynamically manage traffic can also be used to mitigate the negative impacts of concrete pavement construction activities along an active road ( 17 ). Implementation and use of these systems, however, requires contractor resources, and therefore the creation and implementation of an effective and safe traffic control plan is another perceived barrier to implementing concrete overlay solutions.
Construction Personnel
The lack of skilled construction personnel and the lack of available construction personnel are also two potential barriers hindering the implementation of concrete overlays. The results of the 2020 Construction Outlook survey conducted by the Associated General Contractors of America (AGC) indicated that 81% of contractors are having difficulty filling both salaried and hourly craft positions. In addition, the survey results indicate that the top two concerns of contractors were worker quality and worker availability ( 18 ). More specifically, it was identified that entry and mid-level positions in the construction industry in western North Carolina are in the highest demand, and inexperienced employees have a higher turnover rate than those with more experience ( 19 ).
Quality Control Requirements
For all types of concrete pavements, including concrete overlays, monitoring and controlling the critical parameters of a concrete mixture, such as the water-to-cement ratio, air-void system, and aggregate moisture content are vital for producing a concrete pavement that meets or exceeds the project specifications ( 13 ). QC and process control activities are used by the contractor to monitor the quality of a concrete pavement during the construction process. The creation of a project-specific QC plan is critical for ensuring that successful and meaningful QC activities are carried out at the right times. A project-specific QC plan should be comprehensive and cover all aspects of the concrete pavement construction process, and should outline the type and frequency of inspection, sampling, and testing that is needed to measure the various properties that are described in the project specification ( 20 ).
Similar to QC plans for other pavements, a QC plan for concrete overlays should include preliminary material testing, equipment and process monitoring, and testing of concrete, and should focus on the timely collection and response to early test results ( 21 ). Agencies have reported that some contractors provide QC plans that lack sufficient detail to properly control the quality of the pavements they construct. The creation of a project-specific QC plan could potentially be a barrier to the implementation of concrete overlays.
For paving projects of all types, personnel who are involved in both QC and acceptance testing must be properly trained and most agencies require that the testing technicians have proper certification ( 21 ). As previously mentioned, the construction industry is lacking skilled construction personnel, and therefore the lack of QC trained employees can be a barrier to the implementation of concrete overlays.
Fiber-reinforced Concrete
The use of fiber-reinforced concrete can be perceived as a barrier that hinders some concrete paving contractors from bidding on concrete overlay projects. The use of fibers in an overlay concrete mixture can improve concrete performance by increasing the concrete’s toughness, ductility, and flexural strength. This improved concrete performance can support design of thinner panels with larger joint spacing. In addition, fiber-reinforced concrete has the ability to control differential movement and cracking that may develop within a concrete pavement panel. In one study, fiber-reinforced concrete overlays have been shown to provide better performance than similar plain concrete overlays ( 22 ). It should be noted that the use of fibers in an overlay concrete mixture does not replace the use of dowel bars, but can be used to replace tie bars in overlays between 4 and 5 in. in thickness ( 1 , 16 ). Drilling dowels takes time, and when appropriate based on design considerations, use of fiber mixtures in lieu of dowels and tie bars could speed up the construction process. It should be noted, however, that dowel bars have been proven to reduce joint faulting ( 1 ).
Micro synthetic (microfibers, diameter < 0.012 in.), macro synthetic (macrofibers, diameter > 0.012 in.), and steel fibers are the types of fibers that are often used in concrete mixtures. The use of macrofibers improves fatigue performance of the concrete when added in a sufficient dose ( 23 ). In addition, the use of macrofibers can increase the joint spacing beyond conventional recommendations ( 24 , 25 ). As such, macrofibers have been found to provide advantages in overlay concrete mixtures. Macro synthetic fibers are also preferred for use in overlays because of their ability to distribute evenly in the mixture and are recommended for use in thinner overlays that are 4–6 in. thick ( 1 , 16 ).
Fibers should be added continuously with the other materials during the batching process and should be monitored to avoid clumping. Roseler et al. ( 26 ) recommend a dosage rate between 3 and 8 lb/yd3 for macrofibers. The use of high doses of fibers can reduce the slump of the plastic concrete, which can be overcome with the use of a water reducer, such as polycarboxylate. The selection of the fiber type and dosage content should be a contractor decision that is based on the specified residual strength from the pavement engineer or highway agency ( 26 ). The use of fiber-reinforced concrete requires additional technical capabilities and QC monitoring by the contractor. Being unfamiliar or inexperienced with the use of fibers in concrete can hinder the ability of contractors to competitively pursue these types of overlay projects.
Methodology
Sample Description
This survey was conducted in Spring 2021, and the target population of this study was concrete paving contractors that are located within or had a recent history of performing work in the Southeastern U.S.A. Nineteen concrete paving contractors who were either members or previous members of the Southeastern Chapter of the American Concrete Pavement Association (ACPA-SE) were selected, comprising all contractors known to ACPA-SE to have the capabilities of doing overlay work. Overall, 15 of 19 of the contractors that were contacted responded to the survey, a response rate of 78.9%. Of the responses, three respondents did not completely finish the survey, but data provided from these partial surveys were included in this summary statistics.
During the survey the respondents were asked if their company had any concrete overlay experience. The respondents were categorized as either “experienced” or “inexperienced” based on the response to that particular question. Of the contractors who completed the survey 58.3% (7 of 12) of the respondents were categorized as “experienced.” The remaining 41.7% (5 of 12) of the respondents were categorized as “inexperienced.”
Materials and Methods
Each of the participants of this study completed a two-part questionnaire about their concrete overlay experience, and their evaluation and perception about the potential implementation barriers for concrete overlay solutions. The implementation barriers section of the questionnaire utilized a five-point Likert scale, where 1 represented that the perceived barrier was “not important” and 5 represented that the perceived barrier was “most important.” The collected data were quantitatively and qualitatively analyzed to determine the perception of concrete overlay solution implementation barriers as perceived by concrete paving contractors. The data collected from the perceived barriers was statistically analyzed using the Wilcoxon signed-rank sum test to determine if a statistical significance exists between the experienced and inexperienced contractor barrier rankings. The results from the statistical analysis were used to identify if there is a difference in the perceived implementation barriers among the population of experienced and inexperienced concrete paving contractors, which will help the industry have a better understanding of how to increase the use of concrete overlay paving methods. The Wilcoxon signed-rank sum test is a nonparametric test that is used for two dependent samples to determine if the samples are from two different populations ( 27 ).
Results and Discussion
Background Demographics
The respondents who indicated that their company has completed overlay work were asked some additional demographic questions about the type and quantity of overlay that has been completed The respondent was categorized as “experienced” if they indicated that their company had completed concrete overlay work in the past 10 years in the U.S.A., otherwise the respondent was categorized as “not experienced,” which created two populations for this study. Of the experienced contractors, seven (7), four (4), three (3), two (2), and two (2) indicated that they have completed a state, airport, county, private, and city/municipal overlay project in the past, respectively, as shown in Figure 2.
Types of overlay projects.
Figure 3 provides a map of the U.S.A., showing states in which respondents indicated they had performed concrete overlay project(s). Figure 4 provides a summary of the number of concrete overlay projects completed by each contractor in the past 10 years. One of the experienced contractors indicated having a high level of experience with the completion of 20 plus overlay projects with all of them being located in Minnesota, Iowa, and Missouri. The second most experienced contractor indicated that their company had completed 10 overlay projects with the projects being located in North Carolina, South Carolina, Texas, Oklahoma, and Kansas. The remaining experienced contractors indicated that they have completed between one (1) and four (4) overlay projects. Of the contractors experienced in overlay construction, 87% indicated that they have completed an overlay project in the southeast.
Location of respondents for overlay work in the U.S.A.
Number of overlay projects completed in the past 10 years in the U.S.A.
The experienced contractors were asked to indicate the average size of the overlay project that had been completed in the past 10 years. Respondents indicated that 43% of the overlay projects were between 2501 and 10,000 square yards (SY), 28% were between 10,001 and 50,000 SY, and 29% were between 50,001 and 100,000 SY. This indicates that overlay projects over the past 10 years have been small from the perspective of pavement area, but this also indicates that the overlays are being utilized as a targeted solution (Table 1).
Demographic Results
Note: SY = square yards.
The experienced contractors were asked to indicate if the overlay projects in the past 10 years have been related to an intersection or interchange (Table 1). Some 57% indicated that none of the overlay projects were related to an intersection or interchange, 29% indicated that between one and three overlay projects were intersection or interchange related, and 14% indicated that between four and six overlay projects were intersection or interchange related. These responses indicated that while overlay projects have been targeted solutions, they have not been targeted solutions for the rehabilitation of intersection or interchange pavements.
The experienced contractors were also asked what percentage of concrete paving projects included concrete overlay work in the past 10 years: 72% indicated no more than 10%, 14% indicated between 11% and 20%, and 14% indicated more than 20% (Table 1). The responses from this question indicate that concrete overlay work does not represent a significant share of concrete paving contracts.
The experienced contractors were asked if they had constructed concrete overlays over asphalt pavement, concrete overlays over concrete pavement, or others that were not specified in the question (Table 1). These contractors indicated that four concrete overlays over asphalt pavement, five concrete overlays over concrete pavement, and one other unspecified concrete overlay type had been constructed in the past 10 years. These data indicated that concrete overlays have been equally used to rehabilitate existing asphalt and concrete pavements.
Perceived Barriers
The next section of the survey included a list of factors that could be viewed as potential barriers to concrete overlay construction, and contractors were asked to use a five-point Likert scale, where 1 represented that the perceived barrier was “not important” and 5 represented that the perceived barrier was “most important” to rank the barriers. Results from this section are presented in Table 2 and Figure 5.
Perceived Implementation Barrier Results
Note: QC = quality control; Italics are used to designate the ranking of each barrier in the experienced/inexperienced/overall categories.
Barriers to overlay implementation as perceived by contractors.
The demographic data provided by the 19 contractors indicated that there could be two statistically distinct populations in the concrete paving contractors serving the Southeast U.S.A. This possibility was explored using the Wilcoxon rank sum test. The result of the Wilcoxon rank sum test is used to determine if the two sets of data are from the same or different populations by comparing the result to the critical statistic for the data set. The Wilcoxon rank sum critical statistic for “other concerns” was 7 and the remaining barriers had a critical statistic of 21. There were only eight contractors that responded to “other concerns,” which created a lower critical statistic because of the sample size. The null hypothesis for these data is that the medians of the two populations are equal and the alternative hypothesis is that the medians are not equal for the two populations. The Wilcoxon rank sum result (shown in the last column of Table 2) for each barrier is not greater than or equal to the critical statistic (7 for “other concerns” and 21 for all other barriers). Therefore, this test indicated that there is not significant evidence to claim that two separate populations exist in this study. Although the difference in contractor experience was not found to be statistically significant, responses were grouped by “experienced with concrete overlays” and “not experienced with concrete overlays” respondents in Figure 5.
Regardless of the level of experience with concrete overlays, the barriers to implementation were similarly ranked by the concrete paving contractors. The lack of projects that are being let for bid was the most highly ranked (most significant) barrier at 4.1 out of 5 (Table 1). Interestingly, the average rating of inexperienced contractors for “work not being bid” was 4.6, much higher than the 3.7 rating provided by experienced contractors. The “not experienced with concrete overlays” group of contractors had only three responses to the “other concerns” section of the survey, with one of the respondents ranking this barrier as the most important. That contractor stated: Concrete overlays would be a simple cost-effective solution for restoring heavily traveled asphalt roads. The construction method used to complete these projects would be more simplified and “fast track” than traditional concrete paving construction projects. This would allow for more competitive pricing when choosing between asphalt and concrete.
Based on other comments provided in the open response question, contractors in the study indicated that they are eager and ready to construct concrete overlay solutions. One particular respondent noted that none of the identified implementation barriers are insurmountable and the contractors just need opportunities to bid and build more overlay projects.
The survey responses indicated that the second most significant implementation barrier was concerns about traffic control and safety (Table 2 and Figure 5). Traffic control and safety are fundamental elements that must be considered when developing a safe, project-specific work zone strategy, which is also highly dependent on the construction sequence. Taylor et al. ( 28 ) noted that there are numerous easy-to-follow construction staging approaches for concrete overlays, but when the schedule necessitates acceleration, a system approach that considers work zone safety, traffic requirements, and key construction elements should be used to develop a construction staging plan. These authors also explained that the required traffic maintenance criteria should be clearly outlined in the project specifications and the contractor should be given the responsibility to carry out the project to meet the accelerated schedule and traffic maintenance requirements, which allows for the contractor to innovate, plan, and execute the project in a more efficient manner ( 28 ).
Concrete overlays are often laid with adjacent lanes of traffic still remaining open. The clearance that must be maintained around the paving machine is one of the issues that contributes to maintaining a safe and effective work zone. These clearances reduce the lane width that is available for the adjacent lane of traffic during the construction process. The required amount of clearance that is needed is based on the manufacturer and model of the concrete paving machine. Construction agencies and design engineers should not specify a particular piece of paving equipment, but the job specifications should allow the contractor to choose the most appropriate paving machine for the job ( 28 , 29 ). The use of stringless concrete paving machines reduces the required amount of clearance that is needed and eliminates the trip hazard that is created with the use of strings, hubs, and stakes that are required for a traditional concrete paving machine. The amount of time that the adjacent traffic must be safely maintained is influenced by the amount of work that must be completed before the paving operation and the required cure time that must be achieved. Fick ( 29 ) noted that all concrete overlay projects should be accelerated and should open to traffic in 48–72 h from concrete placement, which requires the design of an appropriate concrete mixture that will achieve the proper amount of strength in the shortened time frame. The use of a stringless concrete paver system can eliminate up to 1–4 days per mile of prepaving work because of the elimination of setting up the traditional string control system ( 29 – 32 ). Providing the contractor with the freedom to incorporate innovation in the construction process will allow for the perceived barrier of traffic control and safety to become less of a barrier to implementation.
On average, the third most significant implementation barrier was the lack of available construction personnel, with the lack of skilled construction personnel ranked fourth. The lack of available construction personnel is an industry-wide issue. Al-Bayati et al. ( 19 ) noted that the creation of a certified career pathway for those entering the construction workforce can help to improve the overall recruitment and retention. It is noted that these two barriers were rated notably higher by contractors experienced in overlay construction than contractors inexperienced in overlay construction.
Contractors inexperienced in overlay construction rated barriers of construction being too long and having too many phases, specifications are not clear, and lack of QC trained employees of higher significance (2.6, 2.2, and 2.0, respectively) than contractors experienced in overlay construction did (1.6, 1.6, and 1.7, respectively). The length and complexity of overlay projects, as well as the clarity of specification provisions, could be considered by design professionals. Conversely, contractors could aim to enhance their capabilities through training and technology transfer tools, such as the concrete overlay guide recently updated by the National Concrete Pavement Technology Center ( 1 ). These barriers could also be overcome simply by gaining additional experience if more overlay projects are let to bid. The lack of QC trained employees may be somewhat linked to the general shortages in construction personnel. This shortage could potentially also be addressed by an increased focus on QC training. New publications on concrete paving QC may help bridge this gap ( 21 ).
The final question asked on the survey was whether the respondent was interested in bidding on overlay projects. As shown in Figure 6, the responses clearly indicated that concrete paving contractors in the southeast U.S.A. are eager to bid on overlay projects.
Concrete paving contractors’ interest in bidding on concrete overlay projects.
Conclusions
Concrete overlays present highway agencies and designers with a cost-effective and sustainable pavement rehabilitation method. Some 92% of the contractors who were surveyed indicated a moderate to high level of interest in completing this type of work, which indicates that contractors are likely to bid for these projects if let by agencies. Furthermore, the survey results indicated that the top barrier that is hindering this work is that it is not being specified. Concerns with traffic control and safety was identified as the second most significant implementation barrier. Recently published guidance contains several recommendations about traffic control and safety, and may provide a means to overcome this barrier for many contractors. Additional experience with concrete overlay construction could also allow contractors to become more familiar with the traffic control and safety protocols that are recommended. A shortage of workers, particularly skilled workers, in the construction industry was also identified as a significant barrier. Strategies to increase the construction workforce are being implemented by many agencies, industry/professional organizations, and other entities. The concrete paving contractors surveyed indicated a high willingness to bid on and complete this type of work. With more experience in concrete overlay construction, many of the other barriers identified in this study may be mitigated or eliminated. However, to gain the needed experience, the most significant barrier identified, which is the lack of projects being let for bid and construction, must be overcome. A follow-up study to determine the concrete overlay implementation barriers that exist with the highway agencies and designers could help further promote use of concrete overlay solutions.
Footnotes
Acknowledgements
The authors appreciate the feedback of the North Carolina Department of Transportation (NCDOT) Rigid Pavement Committee on the findings of the survey.
Author Contributions
The authors confirm contribution to the paper as follows: study conception and design: T. Cavalline, M. Sheffield, G. Dean; data collection: G. Dean, M. Sheffield, T. Cavalline; analysis and interpretation of results: M. Sheffield, T. Cavalline, G. Dean; draft manuscript preparation: M. Sheffield, T. Cavalline, G. Dean. All authors reviewed the results and approved the final version of the manuscript.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
