GAO-13-32R Materials and Practices for Improving Pavement Performance

United States Government Accountability Office

Washington, DC 20548

November 14, 2012

The Honorable John J. Duncan, Jr.

Chairman

Subcommittee on Highways and Transit

Committee on Transportation and Infrastructure

House of Representatives

The Honorable Frank LoBiondo

Chairman

Subcommittee on Coast Guard and Maritime Transportation

Committee on Transportation and Infrastructure

House of Representatives

Subject: Information on Materials and Practices for Improving Highway Pavement 

Performance

The nation’s more than 4 million miles of roads are key to the economy, facilitating the 

movement of goods and people. Although highways are highly durable and can last for 

decades, they deteriorate from traffic wear and tear, inadequate drainage, construction 

deficiencies, and weather. Keeping them in good condition requires substantial resources: 

public entities spent more than $180 billion in 2008 on highways, with about $40 billion 

coming from the federal government. Despite these outlays, the Federal Highway 

Administration (FHWA) estimates that these funding levels are insufficient to maintain or 

improve the condition of the nation’s highways through 2028.1

 Further, the major source of 

federal surface transportation funding—federal motor fuel tax revenues deposited into the 

Highway Trust Fund—is eroding.2

 The Congressional Budget Office estimates that, as of 

March 2012, to maintain current spending levels and account for inflation from 2013 to 2022, 

the Highway Trust Fund will require more than $125 billion over what it is expected to take in 

during that period.

3

As a result, state highway agencies, the entities that are ultimately responsible for keeping 

most major highways in good repair, will need to develop strategies for doing so at reduced 

costs.4

 

1 U.S. Department of Transportation, Federal Highway Administration, 2010 Status of the Nation’s Highways, 

Bridges and Transit: Conditions and Performance Report to Congress (Washington, D.C.). 

 One potential strategy is using more cost-effective materials and practices. With 

this in mind and in response to your request, this report describes (1) selected materials and 

2 The Highway Trust Fund is an account established by law to hold and distribute federal highway user taxes 

(e.g., federal excise taxes on fuel) that are dedicated for highway- and transit-related purposes. It is composed of 

two accounts: the Highway Account and the Mass Transit Account. See GAO, Highway Trust Fund: All States 

Received More Funding Than They Contributed in Highway Taxes from 2005 to 2009, GAO-11-918

(Washington, D.C.: Sept. 8, 2011). 3 Congressional Budget Office, March Fiscal Year 2012 Baseline Projections for the Highway Trust Fund

(Washington, D.C.: 2012).

4 Each of the 50 states, plus Washington, D.C., and the Commonwealth of Puerto Rico, has a highway agency.
Page 2 GAO-13-32R Materials and Practices for Improving Pavement Performance

practices that states can use or are using to improve the performance of pavements, 

including what is known about their costs and benefits, if any, and (2) challenges, if any, to 

using these materials and practices. 

To address our objectives, we first conducted a literature search to identify potential 

materials and practices that were reported to increase the durability and the life of 

pavements, thereby improving performance. To supplement the materials and practices 

identified in our literature search, we reviewed and analyzed relevant documentation and 

interviewed officials from FHWA headquarters, asphalt and concrete industry groups, a 

tollway authority, and the American Association of State Highway Transportation Officials 

(AASHTO), as well as pavement researchers from four transportation research 

organizations.5

 We then identified and interviewed officials from seven state departments of 

transportation (DOT)—chosen based on their reported use of materials and practices to 

improve pavement performance, the number of highway miles they managed, and 

geographic diversification—to obtain additional information about materials and practices 

and challenges to their use.6

Through these efforts, we identified and compiled a list of potential materials and practices 

for further evaluation. We assessed each potential practice on whether it (1) has the 

potential to cost-effectively improve pavement performance by increasing durability or 

extending pavement life or has the potential to reduce life-cycle costs—costs associated 

with constructing and maintaining a pavement over its lifetime, and (2) is currently available 

for states to use. We eliminated materials and practices that did not meet these criteria. We 

also identified available cost information and additional benefits provided by these materials 

and practices using the same resources.

 The selection of states was intended to provide a strong 

understanding of states’ experiences and was not intended to be generalizable.

We then verified the accuracy and completeness of the list by identifying a list of 

stakeholders who have relevant expertise in the use of materials and practices with the 

potential to improve pavement performance. We identified potential stakeholders with a 

range of expertise in concrete, asphalt, and highway operations from government, industry 

groups, and transportation research organizations. From this group, we selected nine 

stakeholders who represented a range of expertise and affiliations, and provided them a 

data collection instrument that displayed the initial list of materials and practices we had 

compiled for their review and comment. We asked them if they concurred, did not concur, or 

did not know whether each material and practice has the potential to cost-effectively 

improve pavement performance by increasing durability or extending pavement life, or 

reduce life-cycle costs. We also asked them to identify any materials and practices that meet 

these criteria that we did not include in the list. We received eight responses, which we 

analyzed to identify any materials and practices that a majority of the respondents did not 

concur with. As a result of these responses, we removed two practices from our list and did 

not add others. We organized the materials and practices into five categories to facilitate 

their presentation, shown in tables 2 through 6. In addition, after each table, we discuss 

some considerations associated with the choice of materials or practices by highlighting a 

few examples. Prior to distributing the data collection instrument, we tested our validation 

process with three officials from FHWA and one individual from a private engineering firm. 

We made modifications to the instrument as a result of these tests. We believe our resulting 

list reflects materials and practices that may have the potential to improve pavement 

performance; however, the list was not meant to be exhaustive, and we acknowledge that 

there may be some materials and practices we did not identify.

 

5 We interviewed officials from the National Center for Asphalt Technology, National Concrete Pavement 

Technology Center, Texas A&M Transportation Institute, and Western Research Institute.

6 We interviewed DOT officials from Georgia, Iowa, Minnesota, Tennessee, Texas, Utah, and Washington.
Page 3 GAO-13-32R Materials and Practices for Improving Pavement Performance

To identify challenges to using these materials and practices that states might encounter, 

we conducted a literature search and interviewed DOT officials from seven states. We 

analyzed the information we obtained and categorized challenges into four areas. 

We conducted this performance audit from January 2012 to November 2012 in accordance 

with generally accepted government auditing standards. Those standards require that we 

plan and perform the audit to obtain sufficient, appropriate evidence to provide a reasonable 

basis for our findings and conclusions based on our audit objectives. We believe the 

evidence obtained provides a reasonable basis for our findings and conclusions based on 

our audit objectives.

In summary, our literature review and discussions with stakeholders having relevant 

expertise resulted in the identification of 40 materials and practices that may contribute to 

improving the performance of pavements, extending service life, and reducing life-cycle 

costs. These materials and practices cover a range of uses and applications across the 

stages of a pavement’s life cycle, from initial design and construction through maintenance 

and preservation cycles, and at the time of reconstruction. Several challenges exist to 

states’ use of these materials and practices. In particular, some materials and practices 

may not be applicable or beneficial to all states, a decentralized and segmented highway 

industry may impede change, and resource constraints and procurement methods may limit 

states in implementing new approaches to building and maintaining their highways. 

However, FHWA, AASHTO, and states have developed several programs that address 

these challenges through research, training, and information and outreach programs.

Background

In the United States, state and local governments own about 96 percent of the more than 4 

million miles of roads. State DOTs are responsible for constructing, repairing, and 

maintaining most major highways, including the Interstate Highway System. These 

agencies generally contract with private sector companies to perform these activities. The 

federal government provides funding to states through a series of programs collectively 

known as the federal-aid highway program. Each program that provides funding specifies 

how it can be used—such as for construction, reconstruction, and preventive maintenance 

activities—and specifies eligible project types. Highways supported by federal aid represent 

about one-fourth of all roads, but about 85 percent of all miles traveled annually occur on 

them (see table 1). 

Table 1: Ownership of U.S. Roads by Length in Miles and Vehicle Miles Traveled, 2008

Owner Miles supported

with federal aid

Miles not supported

with federal aid

Total miles

Federal 6,596 124,962 131,559 (3%)

State 562,170 222,141 784,311 (19%)

Local 418,564 2,667,888 3,086,452 (76%)

Other 7,188 49,832 57,020 (1%)

Total 994,518 (24%) 3,064,823 (76%) 4,059,341 (100%)

Vehicle miles traveled 

(millions)

2,534,647 (85%) 458,058 (15%) 2,992,705 (100%)

Source: GAO analysis of FHWA data.

Note: Percentages may not add due to rounding. Other includes state park, state toll, other state agency, other 

local agency, and roadways not identified by ownership. Road lengths and vehicle miles traveled include Puerto 

Rico.
Page 4 GAO-13-32R Materials and Practices for Improving Pavement Performance

Highway pavement consists of several layers of durable material. Lower layers of a 

pavement typically consist of crushed, compacted rock (base or subbase) built on a 

compacted earthen roadbed (subgrade). The surface layer, upon which vehicles travel, is

typically constructed of asphalt or concrete. According to FHWA, of all of the miles of roads 

supported with federal aid, about 91 percent have asphalt surfaces, about 5 percent have 

concrete surfaces, and 4 percent are unpaved.7

Figure 1: Typical Pavement Structure

 Figure 1 illustrates a typical pavement 

structure. 

All pavements deteriorate over time but numerous factors—including increased traffic, water 

intrusion into the pavement layers, freeze/thaw cycles or other weather events, and 

instability of the roadbed or base layers—can accelerate this aging process. Truck traffic, in 

particular, contributes to pavement deterioration, because heavier loads are many times 

more damaging than lighter loads. Evidence of deterioration may be apparent on the

surface layer, as shown in figure 2.

Figure 2: Examples of Deterioration in Asphalt and Concrete Pavements

The activities performed by state and local governments, or their contractors, to build and 

keep pavements in good condition can be organized into four stages, corresponding to 

different points of a pavement’s life: (1) design, (2) construction, (3) maintenance and 

preservation, and (4) reconstruction (see figure 3). 

 

7 Federal Highway Administration, Highway Statistics 2008: Federal-Aid Highway Length – 2008 Miles by Type 

of Surface (Table HM-31), (October 2009), the most recently available data.
Page 5 GAO-13-32R Materials and Practices for Improving Pavement Performance

Figure 3: Stages of a Pavement’s Life Cycle

Designs that appropriately consider factors specific to the highway, such as anticipated 

traffic levels, and construction that meets the design specifications are essential to ensuring 

long-lasting roads. Likewise, maintenance and preservation activities can improve the 

performance of deteriorated pavements and prolong their life by preventing minor problems 

from getting worse and correcting major problems that accelerate deterioration. Over time, 

a pavement may undergo multiple cycles of maintenance and preservation before 

reconstruction is necessary. In addition, throughout these stages, states and contractors 

perform a number of tests, such as testing asphalt and concrete materials before they are 

applied to a road, and use quality assurance and quality control practices, such as testing 

the thickness of new asphalt or concrete, to ensure that pavements meet established 

standards.

Materials and Practices That Can Improve Pavement Performance, Reduce Life-Cycle 

Costs, and Provide Other Benefits 

Selected Materials and Practices 

Our review of existing literature and discussions with stakeholders having relevant expertise 

resulted in the identification of 40 materials and practices—6 materials and 34 practices—

that may contribute to improving the performance of pavements, extending service life, and 

reducing life-cycle costs. Of the 40, 6 are materials that could be used in the construction, 

maintenance and preservation, or reconstruction stages of a pavement’s life. The remaining 

34 are practices; 9 of the practices relate to design and testing, 13 are practices that could 

be used in the maintenance and preservation stage, 8 are practices that could be used in 

the construction or reconstruction stages, and 4 could be used as part of quality assurance 

and quality control activities affecting construction, maintenance and preservation, or 

reconstruction work. 

Pavement Materials 

Table 2 describes six pavement materials that could be used in projects during the 

construction, maintenance and preservation, or reconstruction stages of a pavement’s life

cycle to affect performance. Some can improve the performance of the pavement and base 

materials and increase the durability of the road, while other materials—such as reclaimed 
Page 6 GAO-13-32R Materials and Practices for Improving Pavement Performance

asphalt or recycled concrete—may yield roads with performance characteristics similar to 

those constructed with new materials but at a lower cost. 

Table 2: Pavement Materials

Material Description

Modified asphalt binders Synthetic or natural material added to asphalt to enhance pavement properties. 

Includes polymers, chemical modifiers, rubber, fibers, fillers, and 

biobinders/bioasphalt.

Reclaimed or recycled

material

Re-use of materials into new pavements. Includes asphalt and concrete 

pavement, asphalt shingles, and ground tire/crumb rubber.

Blended or performance 

cements

Material added to the more typical portland cement to enhance concrete 

pavement properties or reduce costs. Includes pozzolans, slag cement, fly ash, 

and limestone.

Concrete curing compounds Material applied to newly poured concrete to inhibit water evaporation and 

ensure proper concrete curing.

Geosynthetics Synthetic polymeric materials used for a variety of purposes in pavement 

structures, such as reinforcement, separation, and drainage. Includes 

geotextiles, geomembranes, geogrids, geocells, and erosion control products. 

Corrosion-resistant 

reinforcement for concrete 

pavement

Materials that resist corrosion and deter corrosion-related damage to concrete. 

Includes fiber-reinforced polymer bars, discrete fibers, stainless steel, and 

epoxy-coated steel.

Source: GAO. 

In reference to reclaimed or recycled materials, officials from each of the states we met with 

said that they allow the use of reclaimed asphalt in asphalt paving projects, typically allowing 

it to comprise up to 20 percent of the asphalt, and some states have investigated use of 

higher levels. Reclaimed asphalt can replace other, more expensive materials when making 

asphalt for pavements. For example, Washington estimates it saves $15 million to $20 

million annually by using reclaimed asphalt. Similarly, recycled concrete is commonly used 

in base or subbase layers of pavement structures and in a more limited capacity in new 

concrete mixes. Using recycled concrete may be less costly, in part because of reduced 

disposal and transportation costs. Georgia officials told us that they not only use recycled

concrete but have approved a recycling center to accept concrete from sources other than 

pavements for use in road construction. 

Concerning use of geosynthetics, officials from all the states we talked with have used 

geosynthetics in base or subbase layers of a pavement structure. Used in this way, the 

materials can improve the stability and strength of those layers. Geoynthetics can also be 

used in the surface layers of asphalt pavements where it may keep water from penetrating 

to the lower pavement layers and may reduce the transfer of cracks from an old pavement 

to a new pavement overlay. However, officials from two states expressed concerns that 

using geosynthetics in this way may create challenges for future pavement repair. For 

example, one pavement preservation practice involves milling, or removing the surface layer 

of an existing asphalt pavement, and replacing it with a new layer of asphalt (see table 4). 

According to one official, geosynthetics used in pavement surface layers might interfere with 

operation of the milling equipment and lead to additional effort to separate geosynthetic 

material from the asphalt millings before they are reclaimed. 

Pavement Design and Material-Testing Practices 

Table 3 describes nine design and material-testing practices affecting pavement 

performance that correspond to the design stage of the pavement life cycle. These include 
Page 7 GAO-13-32R Materials and Practices for Improving Pavement Performance

using different pavement types, such as the use of warm-mix asphalt (WMA) or two-lift 

concrete pavements, and tools that designers could use to predict pavement performance. 

Table 3: Pavement Design and Material Testing Practices

Practice Description

Performance testing of 

asphalt binder

Testing to predict how the binder in asphalt will perform, using procedures such 

as the Multiple Stress Creep Recovery test and the Asphalt Binder Cracking 

Device. 

Performance testing for 

asphalt design mix

Testing to predict how asphalt design mixes will perform using equipment such 

as the Asphalt Mixture Performance Tester.

Using Mechanistic-Empirical 

Pavement Design Guide

A tool that predicts the performance of a pavement being designed based on 

mechanistic-empirical principles.

Optimizing aggregate used 

in pavements

Consideration of aggregate (granular material, such as sand, gravel, crushed 

stone, or recycled concrete) characteristics—such as shape, angularity, and 

texture—in the mix design of asphalt and concrete pavements to improve 

performance. 

Warm-mix asphalt (WMA) Asphalt mix produced and placed at lower temperatures—ranging from 30 to 120 

degrees Fahrenheit lower—than traditional hot-mix asphalt.

Stone matrix asphalt Asphalt mix consisting of coarse aggregate, high asphalt cement content, filler, 

and fibers.

Continuously reinforced 

concrete pavement (CRCP)

Concrete pavement without contraction joints that is reinforced using continuous 

steel bars throughout its length.

Two-lift concrete pavement

Concrete pavement made of two layers: a thick lower layer that can include 

materials that are less resistant to wear and a thinner surface layer made of 

more wear-resistant materials.

Precast concrete panels Sections of concrete pavement that are made off-site and assembled on-site for 

construction and repairs.

Source: GAO. 

In reference to the practice of using WMA, FHWA included it as part of its Every Day Counts 

Initiative to promote innovation; FHWA reported that, as of 2009, more than 40 states had 

constructed WMA projects.8

In addition, according to FHWA, the use of precast concrete panels in highway projects may 

provide pavements in less time and at lower total cost—considering both construction and 

user costs—than using traditional cast-in-place concrete construction methods. For 

example, an FHWA Highways for Life demonstration project used precast concrete panels 

to replace sections of I-66 in Virginia.

 All of the states we spoke with have constructed WMA 

projects. According to the National Asphalt Pavement Association, WMA comprised at least 

15 percent of the asphalt pavement market as of 2010, and in combination with reclaimed 

asphalt, WMA’s use offers significant potential for maintaining well-performing pavements at 

reduced costs. 

9

 FHWA reported that the as-built project yielded 

about a 7 percent savings over the estimated cost of the alternative reconstruction method 

using cast-in-place concrete. Also, Utah officials said that they use precast concrete panels 

in areas requiring rapid pavement repair, such as on highly trafficked highways.

Pavement Maintenance and Preservation Practices 

Table 4 describes 13 maintenance and preservation practices affecting pavement 

performance that could be used during the maintenance and preservation stage of the 

pavement life cycle. These practices include approaches to monitoring the condition of 

 

8 FHWA’s Every Day Counts Initiative is designed to get effective, proven, and market-ready technologies into 

widespread use. This and other FHWA programs are discussed later in this report. 9 FHWA’s Highways for Life is a grant program to demonstrate and promote innovative technologies and 

accelerate their adoption by the highway community.
Page 8 GAO-13-32R Materials and Practices for Improving Pavement Performance

pavements and examples of specific maintenance and preservation treatments that can be 

used to cost-effectively sustain road networks. 

Table 4: Pavement Maintenance and Preservation Practices

Practice Description

Evaluating pavement 

condition using nondestructive technology

Using tools such as deflection testing devices (e.g., falling weight deflectometer), 

ground penetrating radar, ultra-sonic and impact echo devices, and other 

nondestructive testing devices that can be used to noninvasively evaluate the 

condition of pavements.

Pavement 

management/preservation 

system

A network-level, long-term strategy that uses an integrated, cost-effective set of 

pavement maintenance and preservation practices.

Thin or ultra-thin asphalt 

overlay on asphalt 

pavement

Applying a thin (generally 1.5 inches or less) layer of asphalt over an existing 

asphalt pavement.

Mill asphalt pavement and 

resurface with asphalt 

overlay

Removing the surface layer of an existing asphalt pavement and replacing it with 

a new layer of asphalt.

Cold in-place recycling of 

asphalt pavement

Removing existing asphalt pavement, mixing it with new asphalt, and placing the 

re-mixed material as a base layer for a subsequent asphalt overlay.

Surface preservation 

treatments for asphalt 

pavement

Various thin surface treatments applied to asphalt pavement, involving the 

application of liquid asphalt and, in most cases, aggregate. 

Microsurfacing for asphalt 

pavement

Spreading a thin mixture of polymer-modified asphalt emulsion, mineral 

aggregate, mineral filler, water, and other additives on an asphalt pavement.

Diamond grinding for 

concrete pavement

Removing surface imperfections of a concrete pavement using diamond saw 

blades.

Dowel bar retrofit for 

concrete pavement

Installing metal reinforcing bars across joints or cracks that exhibit poor load 

transfer.

Partial-depth repair for 

concrete pavement

Removing and replacing small, shallow areas of a concrete pavement to restore 

localized areas of deterioration.

Full-depth repair for 

concrete pavement

Removing and replacing a segment of concrete pavement through the depth of 

the concrete slab to restore areas of deterioration.

Joint sealing for concrete 

pavement

Applying sealant material to the spaces between jointed concrete pavement 

sections.

Crack sealing for asphalt 

and concrete pavements

Applying sealant material to cracks in asphalt or concrete pavements.

Source: GAO. 

In reference to maintenance and preservation practices, according to FHWA, applying 

treatments to roads in good condition is more economical than reconstructing them after 

they deteriorate: each dollar spent now on pavement preservation could save up to six 

dollars in the future. However, FHWA reports that state DOTs have historically allowed 

pavements to deteriorate to fair or poor condition before taking steps to reconstruct them—a 

costly, time-consuming activity. Pavement management/preservation systems can help 

states monitor the condition of their roads and make decisions to optimize the use of 

resources by applying appropriate preservation treatments at the proper time. 

Several states we spoke with (Georgia, Utah, and Washington) are expanding their use of 

lower-cost surface preservation treatments. Georgia, for example, began using a 

preservation practice involving thin asphalt overlays in 2007.10

 

10 Georgia DOT officials referred to their practice as “micromilling”—removing a thin layer of asphalt from a road 

and replacing it with a new, thin layer of asphalt. 

 According to Georgia 

officials, the cost of this practice is significantly less than the cost of a thicker asphalt overlay 

that they would otherwise place. In addition, Washington has begun using an asphalt 

pavement surface preservation treatment typically used on low volume highways to maintain 

higher-volume asphalt highways. The treatment—known as a “chip seal”, in which liquid 
Page 9 GAO-13-32R Materials and Practices for Improving Pavement Performance

asphalt sprayed on a pavement is covered with aggregate and rolled to embed it—generally 

provides less additional service life to a pavement than milling and replacing the asphalt 

surface.11 However, the life-cycle cost of a chip seal treatment is about one-third that of 

milling and replacing the asphalt surface, according to state officials, and the treatment’s

use should result in lower maintenance and preservation costs over the life of the pavement.

Pavement Construction and Reconstruction Practices 

Table 5 describes eight practices that could be used during the construction and 

reconstruction stages of the pavement life cycle to affect pavement performance. These 

practices include specific approaches to building or rebuilding roads that may enhance their 

durability. 

Table 5: Pavement Construction and Reconstruction Practices

Practice Description

Subbase and base layer 

treatments

Using cement, asphalt, geosynthetics, or other materials to improve the subbase 

or base layers of a roadway.

Intelligent compaction

Using compaction equipment that measures compaction levels and provides 

feedback to allow adjustments to ensure base materials and asphalt are 

compacted completely and correctly.

Asphalt structural overlay for 

asphalt pavement

Adding pavement layers to increase the pavement’s load-carrying capacity.

Full-depth reclamation for 

asphalt pavement

Pulverizing the existing asphalt pavement and mixing it with the underlying base 

material for use as the base for a new asphalt surface layer.

Concrete overlay 

(whitetopping) for asphalt 

pavement

Applying a layer of concrete (generally 2-11 inches) over an existing asphalt 

pavement.

Asphalt overlay for concrete 

pavement

Applying a layer of asphalt over an existing concrete pavement.

Rubblization/crack and seat 

with asphalt overlay for 

concrete pavement

Fracturing existing concrete pavement into small pieces (less than 3 feet) and 

placing a new asphalt pavement over this base.

Concrete overlay for 

concrete pavement

Placing a layer of concrete (generally 2-11 inches) over an existing concrete 

pavement.

Source: GAO. 

According to FHWA, properly compacting pavement materials, such as subbase rock and 

asphalt, is one of the most important elements in constructing long-lasting pavements. 

Compacting equipment with intelligent compaction systems can ensure that pavement 

material is compacted correctly and completely. Three of the seven states we met with 

(Georgia, Minnesota, and Texas) participated in a study aimed at accelerating the 

implementation of intelligent compaction, working with equipment suppliers, for example, to 

increase awareness of the technology. 

In addition, since the early 1990s, according to FHWA, the use of whitetopping has grown 

significantly in the U.S., as newer techniques for bonding the new concrete to the old 

pavement have allowed for use of thinner concrete layers (2 to 6 in.) over existing asphalt 

pavements. A potential benefit to whitetopping repair is the durability of concrete, which 

results in a greater interval between reconstruction treatments compared to use of an 

asphalt overlay. Colorado has conducted many whitetopping projects and, of the states we 

spoke with, Iowa officials said that whitetopping is used extensively on county roads in their 

state. 

 

11 “Aggregate” is granular material, such as sand, gravel, crushed stone, or recycled concrete.
Page 10 GAO-13-32R Materials and Practices for Improving Pavement Performance

Quality Assurance and Quality Control Practices 

Table 6 describes four quality assurance and quality control practices that could be used 

during the construction, maintenance, or reconstruction stages of a pavement’s life cycle to 

affect performance. These practices include specific devices that can be used and actions 

that can be taken to ensure constructed work meets the level of quality intended by the 

design. 

Table 6: Quality Assurance and Quality Control Practices

Practice Description

Infrared thermography for 

asphalt pavement

Devices that non-destructively measure temperature variation in asphalt as 

pavements are constructed to identify possible quality problems.

Smart Cure System A system of devices that provides on-site, real-time recommendations to achieve 

optimal concrete curing based on ambient conditions.

Magnetic imaging 

tomography

A non-destructive testing device that determines the thickness of fresh concrete 

pavement.

Warranties

A warranty establishes the expected performance of a product (such as a newly 

constructed road or repair of an existing road) and the responsibility to repair or 

replace defects for a defined period.

Source: GAO. 

According to FHWA, “infrared thermography”—equipment that measures the temperature of 

asphalt as it is placed by a paving machine—can help ensure asphalt is placed at the 

appropriate temperature, which is a critical factor in preparing uniform, high-quality 

pavements. Knowing the temperature helps to better identify and immediately correct parts 

of the road where temperatures are not sufficiently uniform and failures are likely to occur. 

Officials in four of the states we spoke with (Georgia, Minnesota, Texas, and Washington) 

said their states have experimented with the use of infrared equipment on paving machines. 

A Minnesota DOT evaluation of infrared thermography (see table 6) and intelligent 

compaction (see table 5) concluded that both practices can be used as effective quality 

assurance tools to improve pavement performance. 

In addition, FHWA encourages the use of pavement warranties and notes that the most 

benefit comes from long-term performance warranties (generally ranging from 10 to 20 

years). While use of warranties shifts some risk to the contractor—which can raise project 

costs —FHWA notes that increased contractor responsibility should allow greater freedom 

for innovation. None of the states we spoke with said they are currently using warranties. 

Officials from five states that had used or considered using warranties noted that contractors 

may be challenged to provide long-term warranties because of the cost of holding a bond 

over the term of the warranty.12

Potential Cost Savings of These Materials and Practices Varies and Can Be Assessed 

Using Life-Cycle Cost Analysis 

By improving the durability or extending the service life of pavements, the materials and 

practices described in the preceding tables may decrease the life-cycle costs of a 

pavement—that is, the costs associated with constructing and maintaining a pavement over 

its lifetime.13

 

12 A bond, secured through a surety, guarantees contractor performance throughout the warranty period. 

 The cost of a pavement is dependent on a range of factors that may be 

specific to an individual state or project, including climate, traffic, and geologic conditions. 

13 GAO will be conducting work during the next year on best practices for calculating life-cycle costs and benefits 

for federally funded highway projects, as mandated by the recent adoption of 23 U.S.C. § 503(b)(3)(D)(ii) by the 

Transportation Research and Innovative Technology Act of 2012. Pub. L. No. 112-141, Div. E, Title II, 

§ 52002(b), 126 Stat. 405, 866-875 (July 6, 2012).
Page 11 GAO-13-32R Materials and Practices for Improving Pavement Performance

For example, constructing a pavement in a northern state that experiences frequent freezethaw cycles may involve different factors than constructing a pavement in a southern state 

that rarely does. Likewise, constructing a pavement to accommodate high levels of truck 

and other vehicle traffic may involve different factors than constructing a pavement to 

accommodate relatively low levels of traffic. 

A state DOT may conduct a life-cycle cost analysis to compare construction and 

maintenance alternatives—and the possible materials and practices associated with each—

in determining approaches to building and maintaining pavements. For each alternative, the 

analysis provides projections based on initial costs, such as material and construction costs, 

and future costs—such as maintenance, user, and reconstruction costs—over the life of a 

project. For example, a state may perform life-cycle cost analysis to compare the costs of 

using asphalt or concrete as surface layer materials to construct or reconstruct a road.

Some states we met with had used life-cycle cost analysis to inform key decisions. For 

example, in 2005, Utah DOT assessed two of its existing asphalt surface preservation 

treatments—an open-graded surface course and a chip seal—and found the chip seal 

treatment to be much more cost-effective.14 The analysis showed that expanding the use of 

chip seals and limiting use of open-graded surface courses to certain high volume roads 

could result in a savings of over $2 million per year. Similarly, the Georgia DOT conducted 

a life-cycle cost analysis to compare the costs of using conventional asphalt and stone 

matrix asphalt (see table 3). While stone matrix asphalt is more expensive than 

conventional asphalt, it is highly durable and can provide a 30 to 40 percent increase in 

pavement life. In its analysis, Georgia considered that the stone matrix asphalt would need 

less frequent maintenance and repair, resulting in estimated annualized costs that were 37 

percent less than using conventional asphalt. This analysis led Georgia to select use of 

stone matrix asphalt based on its overall lower life-cycle cost. 

Some Materials and Practices May Provide Additional Benefits 

Some of the materials and practices described in the preceding tables offer additional 

benefits, beyond improving pavement performance, for example: 

• Incorporating reclaimed or recycled materials (see table 2) into highway pavements 

provides an environmental benefit by making use of a material that might otherwise 

be disposed of and reducing the amount of new material needed. 

• Using precast concrete panels (see table 3) can provide a benefit to users of the 

road under repair. Concrete that is placed on-site may take several days to cure, 

and during that time, affected lanes must remain closed to traffic. Conversely, 

precast panels may be driven on immediately, thereby reducing the inconvenience to 

drivers. 

• Following the principles of a pavement management/preservation system (see table 

4) can provide sustainability benefits because these tools seek to minimize the 

amount of natural resources used over a pavement’s life cycle. 

Potential Challenges to Implementing Materials and Practices

Although the materials and practices identified in this report may offer states opportunities 

for savings and improved pavement performance, certain factors could prevent states from 

implementing them. In our review of literature regarding these factors, we identified 

challenges in four areas that could affect the extent to which state DOTs implement 

 

14 An “open-graded surface course” is an asphalt pavement treatment that is water-permeable. Its use can 

reduce spray from water on the road and provide a quieter ride.
Page 12 GAO-13-32R Materials and Practices for Improving Pavement Performance

materials and practices. In our interviews with state DOTs, officials also identified challenges 

in these same areas. FHWA and others have developed several ongoing programs and 

efforts to overcome these challenges.

Literature Review Identified a Range of Challenges 

Our literature review identified challenges in the following four areas that might prevent state 

DOTs from implementing materials and practices: 

• Suitability of Materials and Practices: In some cases, a particular material or practice 

may not be applicable or beneficial to all states. Because of differences in climate, 

sources of raw materials, and other factors, a material or practice that works well for 

one state may not work well for another. For example, two-lift concrete pavement

(see table 3)—which allows lower quality aggregates to be used in a lower level of 

the pavement—may be beneficial in a state where good aggregates for pavement 

have to be transported in at a high cost. However, in a state with an abundant 

supply of good aggregates, using two-lift construction may not be cost-effective. In 

other cases, a state may find that a material or practice has not been sufficiently 

tested, or that the results of testing are not sufficiently quantifiable. This is in part 

because, given the long-lasting nature of pavements, the results of testing or using a 

practice may not be known for 10 years or more. Finally, highway pavement 

systems are complex, and interaction between different components makes it difficult 

to understand how the implementation of a material or practice may affect other 

components. 

• Structure and Culture of the Industry: As we and others have previously reported, the 

highway industry is highly decentralized and segmented.15

• Resources: Insufficient funding to implement new materials and practices can limit 

states’ use of them, as the budget or cost required may exceed the level 

management is willing to support. Limited staff resources because of decreased 

agency size, staff turnover, or lack of staff with technical expertise may also prevent 

a state DOT from implementing a material or practice. As a result, staff may not 

have time or expertise to take on the additional workload required to implement a 

material or practice, such as writing new specifications for the practice. 

 There are about 35,000 

different federal, state, and local entities responsible for constructing, operating, and 

maintaining U.S. highways. In addition, there are many private companies of many 

sizes and specialties that carry out highway design work and much of the highway 

construction work, and that supply materials, equipment, and services used by public 

agencies. As a result, it takes time to overcome implementation challenges in each 

agency to achieve widespread use of a material or practice. In addition, a number of 

reports have pointed to a cultural resistance to change in the highway industry. 

State DOTs and other public agencies are risk averse because success can bring 

minimal rewards and the cost of failure can be high. As a result, an agency’s 

leadership may not provide sufficient support and direction to encourage innovation. 

Likewise, highway contractors may be reluctant to invest in new technologies without 

an assurance that a state DOT will share the risk of using them. 

 

15 GAO, Highway Technology: The Structure for Conducting Highway Pavement Research, GAO/PEMD-88-2BR

(Washington, D.C.: Nov. 13, 1987); GAO, Highway Infrastructure: Federal-State Partnership Produces Benefits 

and Poses Oversight Risks, GAO-12-474 (Washington, D.C.: Apr. 26, 2012); Transportation Research Board, 

Special Report 261 The Federal Role in Highway Research and Technology (Washington, D.C.: 2001); and

Transportation Research Board, Special Report 296 Implementing the Results of the Second Strategic Highway 

Research Program: Saving Lives, Reducing Congestion, Improving Quality of Life (Washington, D.C.: 2009). 
Page 13 GAO-13-32R Materials and Practices for Improving Pavement Performance

• Procurement and Specifications: Public agencies use procurement methods that can 

inhibit them from implementing new materials and practices. The low bid system, 

whereby a state DOT accepts the lowest bid that meets the terms of a public 

proposal, may limit both the state’s and contractors’ ability to introduce innovation 

that might cost more to construct, but have a lower life-cycle cost. Some agencies 

use an initial cost criterion to determine whether to use a new practice; although a 

new practice can be initially more costly than an existing practice, it might provide 

lower costs over its lifetime. Implementing a new technology may require a DOT to 

revise its specifications to allow its use. Most highway agencies have their own 

specifications and revising them may require the coordination of several 

organizational entities, increasing the difficulty of the task. Finally, state DOTs may 

find it is not always easy to use proprietary products. These products are usually not 

allowed, because they could limit competition and may not conform to a state’s 

standard design specifications. 

State DOTs Identified Challenges Similar to Literature Review

In our interviews, state officials identified challenges they experienced in implementing new 

materials and practices similar to the suitability, culture, resources, and procurement areas 

identified above. Most examples they provided, however, involved issues with the suitability 

of materials and practices. 

• Suitability of Materials and Practices: In at least three instances, state officials 

reported that they had success with a practice that had not worked well in another 

state. For example, in Texas, officials stated they use CRCP (see table 3) 

extensively and have had good experiences with them. However, Iowa officials said 

they have used CRCP in the past but believe them to be cost-prohibitive and have 

experienced good performance with jointed concrete pavements. In addition, 

Georgia has used stone matrix asphalt (see table 3) on its Interstates and other highvolume highways because of its durability. However, in the neighboring state of 

Tennessee, officials stated that they evaluated stone matrix asphalt, decided the 

initial cost was too high, and have not widely adopted its use. 

A state DOT may be less willing to implement a practice that is not well-understood 

or not perceived to have sufficient benefits. For example, Minnesota officials said 

they tried requiring extended warranties (see table 6) but found the costs prohibitive 

for contractors to bond the projects over the warranty period. Because these costs 

are passed on to the DOT in the form of higher bids on contracts, the officials said 

they determined that the increased costs were greater than the benefit provided by 

the warranties and discontinued the practice. Also, Washington officials stated that 

they have not used two-lift concrete (see table 3) because they know their locally 

available materials and current construction practices work well. 

Materials and practices that have not been sufficiently tested may present a 

challenge. For example, Washington officials told us that even though there might 

be research on a particular practice, they will not necessarily implement it until they 

verify reasonable performance and that the practice will work on their state’s roads. 

In addition, Tennessee officials stated they used recycled shingles (see table 2) on a 

few projects and are planning more, but additional testing is needed. They stated 

that specifications routinely allowing the recycled shingles could be up to a year 

away. 

Potential or actual interactions between different paving materials may also present a 

challenge to implementing new materials and practices. According to state officials, 

Georgia specifications allow up to 40 percent reclaimed asphalt pavement (see table 
Page 14 GAO-13-32R Materials and Practices for Improving Pavement Performance

2), but contractors typically use less—about 25 to 30 percent—because using more 

can prevent them from complying with other specifications designed to decrease 

pavement deterioration. Similarly, Utah specifications allow blended cements (see 

table 2), and state officials said that they generally perform as well as standard 

concrete mixes. However, these officials have found that blending cement with 

locally sourced limestone does not allow the concrete to strengthen quickly and thus 

should not be used in cases where this characteristic is desired.16

A negative experience with a practice may prevent a state from using the practice 

again. Tennessee officials said they used recycled tire rubber (see table 2) in three 

asphalt paving projects in 1993 and 1998, and two of the pavements failed early, so 

they did not adopt further use of the material.17

• Structure and Culture of the Industry: Tennessee officials stated that they are open 

to looking at new materials and practices but are not willing to get too far ahead of 

everyone else. In addition, states may meet resistance from contractors when 

implementing materials and practices that are new to them. Georgia and Minnesota 

officials stated that they had received resistance from contractors to implementing

the use of intelligent compaction (see table 5) or infrared thermography (see table 6). 

For example, Georgia DOT officials stated that they had received resistance from 

contractors to implementing the use of intelligent compaction because the costs to 

purchase the equipment is high, and the investment in equipment, without a 

requirement from a state for its use, is difficult to justify. Minnesota DOT officials 

said that they had also received resistance from some contractors to implementing 

the use of infrared thermography because it brings added complexity and the 

investment in equipment without a commitment from the state for its future use was 

difficult to justify. While one of the contractors that purchased an infrared paving bar 

has continued to use it, another contractor only used it on the job for which it was 

required. Similarly, Utah officials stated that while the use of optimized grading of 

aggregates for concrete pavement (see table 3) could be beneficial, the 

implementation has been very slow due to industry’s resistance to making costly 

required changes to concrete plants. Utah officials noted that while they are 

modifying their specifications to allow the use of a wider range of materials and 

practices, it is up to the contractors to include them in their bids to the state.

 Utah officials said they stopped 

using geosynthetics (see table 2) in pavements because they found it was not as 

effective in inhibiting the transfer of cracks from the old pavement to the new 

pavement overlay as expected. 

• Resources: Minnesota officials stated there are more materials and practices they 

would like to evaluate than available funds or staff to do it. As a result, they use 

professional engineering judgment to select materials and practices to evaluate 

based on the likelihood of implementation. Georgia officials stated that with the 

continued downsizing of staff, they will have little expertise remaining in their 

organization to change specifications to allow new materials and practices. Iowa 

officials noted that reduced travel because of budget reductions is sometimes a 

challenge, resulting in a reduction of the staff’s ability to adequately understand new 

materials and practices and implement them. 

• Procurement and Specifications: Minnesota officials wanted to try intelligent 

compaction (see table 5) on a project but could not require its use because they 

lacked a specification. As a result, they worked with an equipment manufacturer and 

16 This characteristic, known as “high early strength,” refers to concrete that achieves its specified strength at an 

earlier age than normal concrete. High early strength concrete used in repair or construction projects, for 

example, can carry traffic within a few hours after the concrete is placed.

17 Tennessee officials told us that they used recycled tire rubber in an asphalt paving project in 2011 that is 

currently performing satisfactorily.
Page 15 GAO-13-32R Materials and Practices for Improving Pavement Performance

distributor to outfit compaction equipment with intelligent compaction systems and 

conducted two pilot projects. Based on these pilot projects, officials developed 

contract specifications pertaining to intelligent compaction systems. They expect to 

start using these specifications in contracts beginning in 2013. Texas officials stated 

they wanted to use a promising new aggregate in their concrete pavements that 

improves concrete quality. However, the material is only produced by one 

manufacturer, limiting their ability to specify it in requests for contract proposals. 

Similarly, Utah officials wanted to use proprietary asphalt materials in their cold inplace recycling (see table 4) and full-depth reclamation (see table 5) practices. 

Although they cannot specify proprietary products, the officials said that their effort to 

change to performance-based specifications might enable them to overcome this 

challenge. Performance specifications require a contractor to meet functional criteria 

such as strength and durability, without prescribing use of specific materials or 

practices. As a result, contractors may choose to use proprietary materials or 

practices to meet performance requirements. 

Agencies Have Implemented Various Programs and Efforts to Overcome These Challenges

FHWA, the Transportation Research Board (TRB), AASHTO, and states have developed 

several programs that address the challenges of developing new materials and practices 

through research, training, information and outreach programs, demonstration projects, and 

other incentives.

18 The following are some of the programs the agencies and organizations 

have in place to promote the use of pavement materials and practices and other highway 

improvements.

FHWA

FHWA works with state, industry, and trade associations’ stakeholders to develop and 

implement new materials and practices through the following programs:

• Advanced Concrete Pavement Technology Products Program: A national 

technology transfer effort to improve the long-term performance and costeffectiveness of the nation's concrete pavement highways by identifying, refining, 

and delivering the available technologies that can enhance the performance of 

concrete highways. Some of the materials and practices the program is advancing 

include mechanistic-empirical concrete pavement design (see table 3), concrete 

overlays (see table 5), and the use of recycled materials (see table 2).

• Every Day Counts Initiative: A program designed to get effective, proven, and 

market-ready technologies into widespread use. Warm-mix asphalt (see table 3) is 

one of the practices the program has featured.

• Highways for Life: A grant program to demonstrate and promote innovative 

technologies and accelerate their adoption by the highway community.19

 

18 TRB is a unit of the National Research Council within the National Academy of Sciences whose mission is to 

provide leadership in transportation innovation and progress through research and information exchange. TRB 

is supported by state transportation departments, federal agencies, including the component administrations of 

the U.S Department of Transportation, and other organizations and individuals interested in the development of 

transportation.

 We 

observed a demonstration project partially funded by this program that included four 

of the materials and practices we identified in the previous section of this report, 

including use of optimized aggregate (see table 3 and fig. 4), intelligent compaction 

19 This program was authorized as a pilot program under section 1502 of the Safe, Accountable, Flexible, 

Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU), Pub. L. No. 109-59, 119 Stat 1144, 

1236-1237 (2005).
Page 16 GAO-13-32R Materials and Practices for Improving Pavement Performance

(see table 5), geosynthetics (see table 2), and curing compounds (see table 2 and 

fig. 5).20

Figure 4: Concrete Plant Producing Optimized Aggregate Concrete for the Highways for Life Project in 

Tarrant County, Texas, 2012 

Figure 5: Application of Concrete Curing Compound at the Highways for Life Project in Tarrant County, 

Texas, 2012

• Long-term Pavement Performance Program: A 20-year study of in-service 

pavements across North America. The program’s goal is to extend the life of 

highway pavements through various designs of new and rehabilitated pavement 

structures using different materials and under different loads, environments, 

subgrade soils, and maintenance practices. One of the more recent results of this 

 

20 The project included construction of a 2.2 mile section of continuously reinforced concrete pavement in Tarrant 

County, Texas, on FM 1938 from SH 114 to Randol Mill Road. FHWA, through its Highways for Life Program, 

provided a grant of $1 million on this estimated $16.5 million project.
Page 17 GAO-13-32R Materials and Practices for Improving Pavement Performance

study is guidance on selecting the most effective pavement preservation treatments 

for asphalt pavement (see table 4). 

• Transportation Pooled Fund Program: Interested states, FHWA, and other 

organizations may pool funds and other resources for new areas of research, 

planning, and technology innovation or to provide information that will compliment or 

advance previous efforts in these areas. 

• International Technology Scanning Program:21

• Technology Innovation and Deployment Program: Section 503(c)(3)(C) of Title 23, 

United States Code, now requires that the Secretary of Transportation obligate at 

least $12 million per year to accelerate the deployment and implementation of new 

pavement innovations and technology.

An FHWA program to help states and 

industry access innovative materials and practices from other countries. The 

program helped entities adapt and put into practice highway innovations without 

spending research funds to re-create advances already developed by other 

countries. Past scans included providing information on asphalt and concrete 

pavements, pavement preservation (see table 4), superior materials, reclaimed or 

recycled materials (see table 2), and many other non-pavement related topics.

22

TRB

TRB also has several programs that are providing additional research to and helping to 

share information regarding new materials and practices with states. 

• National Cooperative Highway Research Program (NCHRP): Conducts research in 

problem areas that affect highway planning, design, construction, operation, and 

maintenance nationwide. Its efforts include helping state DOTs put the findings to 

early use in the form of policies, procedures, specifications, and standards. Two 

subprograms are involved within NCHRP:

• The Innovations Deserving Exploratory Analysis program funds research into 

innovations for design, construction, materials, operations, maintenance, and 

other areas of highway systems. 

• The U.S. Domestic Scan Program is designed to identify materials and practices 

being used within the United States that might be beneficial to other states and 

then disseminate those materials and practices to others. 

• Strategic Highway Research Program (SHRP): The first Strategic Highway 

Research Program (1988 to 1993) changed asphalt pavement design by producing a 

new method for designing pavements that reduced distress, resulting in better 

performing and longer lasting pavements. The second Strategic Highway Research 

Program (SHRP 2) (2006 to 2015) was authorized by Congress to address some of 

the needs related to the nation’s aging highway system, including renewal of roads 

through construction methods that produce long-lived facilities. Some of the work 

related to pavements undertaken in SHRP 2 includes precast concrete pavement 

technology (see table 3), infrared thermograpghy (see table 6), and ground 

penetrating radar (see table 4). 

 

21 This program was conducted under section 5206 of SAFETEA-LU, known as the International Highway 

Transportation Outreach Program, Pub. L. No. 109-59, 119 Stat., 1795-1796.

22 23 U.S.C. § 503(c)(3)(C) as amended by the Transportation Research and Innovative Technology Act,

§ 52003, 126 Stat., 879-880.
Page 18 GAO-13-32R Materials and Practices for Improving Pavement Performance

AASHTO

AASHTO has groups to assist DOTs in overcoming the challenges of implementing 

materials and practices. 

• National Transportation Product Evaluation Program: Evaluates materials, products, 

and devices for use in highway and bridge construction. The program’s goal is to 

provide cost-effective evaluations for state DOTs by eliminating duplication of testing 

and auditing by the states and manufacturers that provide products. Some of the 

materials and practices being evaluated include warm-mix asphalt (see table 3), joint 

sealing for concrete pavement (see table 4), crack sealing for asphalt pavements 

(see table 4), concrete overlays (see table 5), concrete curing compounds (see table 

2), and geosynthetics (see table 2).

• Technology Implementation Group: Identifies and champions the implementation or 

deployment of a select few proven technologies, products, or processes that are 

likely to yield significant economic or qualitative benefits to the users. Some of the 

pavement technologies promoted include precast concrete pavement slabs (see 

table 3) and hot in-place asphalt pavement recycling.

State DOTs

Officials at some of the state DOTs we interviewed said that in addition to working with 

FHWA and others, they had their own efforts under way to evaluate and implement new 

materials and practices. For example, Minnesota officials told us the state created a $20 

million innovation program in 2010 which can pay for the incremental costs associated with 

using practices such as intelligent compaction (see table 5).23 In one case, the state paid a 

contractor to outfit its construction equipment to use intelligent compaction, thus reducing 

the reluctance of the contractor to bid the project and buy equipment it might not use again. 

In another instance, the state used the funding to pay for a new asphalt-patching material for 

use by its maintenance division. This purchase allowed the state to become familiar with 

the product and develop specifications for potentially continuing its use. 

Agency Comments

We provided U.S. Department of Transportation (DOT) with a draft of this report for review. 

U.S. DOT did not comment on the draft report. We also provided each of the seven state 

DOTs we spoke to with a draft of relevant sections of this report for review. Each provided 

technical comments, which we incorporated as appropriate. 

-----------

We are sending copies of this report to congressional committees with responsibilities

for surface transportation issues, the Secretary of Transportation, the Administrator of the 

Federal Highway Administration, and other interested parties. In addition, this report is 

available at no charge on the GAO website at http://www.gao.gov. 

 

23 The program was funded with $15 million in 2012.
Page 19 GAO-13-32R Materials and Practices for Improving Pavement Performance

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Wood.

Lorelei St. James 

Director, Physical Infrastructure Issues 

(544175)
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