Exploratory Advanced Research . . . Next Generation Transportation Solutions

age and have included reducing the waterto-cementitious-materials ratio, using mineral 

admixtures, and adding shrinkage-reducing 

admixtures. The SRCC approach in this project, 

however, will address not only cracks caused 

by shrinkage but also those related to thermal 

changes, expansive corrosion reactions, ASR 

expansions, and other causes.

The consequences of reducing cracking in 

concrete would be far-reaching. “If the research team succeeds in this project,” says Rick 

Meininger of FHWA’s Office of Infrastructure 

Research and Development, “their results could 

dramatically increase the service life of new 

concrete infrastructure. In addition, SRCCs 

could prove to be superior materials for longlasting concrete repairs.” 

Relaxing High-Tensile Stresses

To maximize the prospects of success, the 

study will investigate SRCCs on two scales, 

using two models. On the nano to micrometer 

scale, materials being explored include surfacetreated carbon nanotubes, silica fume, metakaolin, fly ash, limestone powder, and rice husk 

ash. The stress-relaxation effect of these materials occurs as nano (or micro) cracks form 

at the interface of the cement paste matrix 

molecules and the embedded SRCC molecules, 

releasing energy. After crack formation, further 

relaxation results from sliding friction at the 

interface.

On the micrometer to millimeter scale, various types of waste plastic are being investigated 

for their ability to increase concrete’s viscoelasticity. Should this method prove successful 

and be widely adopted, it could benefit the 

environment tremendously. Plastics occupy 

about 25 percent of the total volume of landfills, and their manufacture consumes about 

10 percent of the country’s total fossil fuel 

use. Only 5 percent of plastics produced in the 

United States are now recycled.

The Exploratory Advanced Research Program Fact Sheet

Designing the Concrete of the Future

Concrete transportation structures are subject to 

cracking that leads to deterioration—corrosion, 

weakening due to sulfate attack, and damage 

from alkali-silica reactivity. These problems 

shorten the service lives of bridges, tunnels, and 

pavements and reduce their level of performance. The goal of this EAR project is to design 

concretes with increased resistance to cracking. 

Paradoxically, one method proposed introduces 

controlled cracking on a nano to micrometer 

scale to lower the tensile stresses in concrete to 

a level where they will not cause macroscale 

cracking or curling. This relaxation would be 

induced by utilizing stress-relaxing cementitious 

composites (SRCCs), which are achieved by 

embedding nano to micrometer scale inclusions 

that reduce the concrete’s brittleness without 

sacrificing its strength. 

Previous attempts to limit cracking have 

focused mainly on cracking caused by shrinkCrack-free concrete? Although much 

progress has been made in reducing 

concrete’s propensity to crack, the goal 

remains elusive. A novel approach to this 

problem is the focus of “High-Performance Stress-Relaxing Cementitious 

Composites for Crack-Free Pavements 

and Transportation Structures,” an Exploratory Advanced Research (EAR) Program 

project launched by the Federal Highway Administration (FHWA) in 2008 and 

conducted at Texas A&M University’s 

Texas Transportation Institute.

Crack-Resistant Concrete 

Maximizing the Service Life of Transportation Infrastructure
Key Challenges

The most challenging technical areas of the 

work underway include the risk of not being 

able to produce a substantial increase in stress 

relaxation and the difficulty or expense of treating materials to increase their stress-relaxing 

contribution. The simultaneous investigation 

of materials at two size scales is intended to 

mitigate the risk of failure. 

The SRCC models are being validated through 

direct measurement via stress-relaxation or 

creep tests. Once stress relaxation is validated, 

the ability of the SRCCs to resist cracking under 

stresses will be evaluated and compared to that 

of conventional portland cement concrete. 

Future Efforts

This project will prove successful if it is able to 

make a concrete that is 50 percent less likely 

to crack in a typical concrete transportation 

infrastructure under typical service conditions. 

With that achievement, the project will produce 

a design methodology and written guidelines—

easy to follow, using standard measurements 

and equipment—for the design of SRCCs. These 

products will stimulate more research on the 

topic and further the implementation of new 

crack-resistant concrete designs. The project is 

expected to conclude in 2010.

Learn More

For more information on this EAR Program project, contact Richard Meininger, FHWA Office of 

Infrastructure Research and Development, at 202-

493-3191 (email: richard.meininger@dot.gov).

What Is the Exploratory 

Advanced Research Program?

FHWA’s Exploratory Advanced Research 

(EAR) Program focuses on long-term, 

high-risk research with a high payoff 

potential. The program addresses underlying gaps faced by applied highway 

research programs, anticipates emerging issues with national implications, and 

reflects broad transportation industry 

goals and objectives. 

To learn more about the EAR Program, visit the Exploratory Advanced 

Research Web site at www.fhwa.dot.gov/

advancedresearch. The site features information on research solicitations, updates 

on ongoing research, links to published 

materials, summaries of past EAR Program events, and details on upcoming 

events. For additional information, contact 

David Kuehn at FHWA, 202-493-3414 

(email: david.kuehn@fhwa.dot.gov), or 

Terry Halkyard at FHWA, 202-493-3467 

(email: terry.halkyard@fhwa.dot.gov).

Publication No. FHWA-HRT-09-065

HRTM-04/08-09(1M)E

Crack-Resistant Concrete 

Maximizing the Service Life of Transportation Infrastructure

Image other side: 

Carbon nanofibers spanning 

nano/micro crack in a 

cementitious composite.