TECHBRIEF Simultaneous Structural and 

Environmental Loading 

of a UHPC Component

FHWA Publication No: FHWA-HRT-10-055 

FHWA Contact: Ben Graybeal, HRDI-06, 202-493-3122, benjamin.

graybeal@dot.gov

This document is a technical summary of the unpublished Federal 

Highway Administration (FHWA) report, Simultaneous Structural 

and Environmental Loading of an Ultra-High Performance Concrete 

Component, available through the National Technical Information 

Service (NTIS).

NTIS Accession No. of the report covered in this TechBrief: 

PB2010-110331

Objective

This TechBrief highlights the results of a study aimed at evaluating the inelastic tensile response of ultra-high performance 

concrete  (UHPC) subjected to simultaneous structural and 

environmental loading. 

Introduction

UHPC is an advanced cementitious composite material that has 

been developed in recent decades. When compared to more 

conventional concrete materials, UHPC tends to exhibit superior 

properties such as exceptional durability, high compressive 

strength, usable tensile strength, and long-term stability.(1,2)

Practical application of concrete in the highway infrastructure 

frequently subjects cracked sections to simultaneous mechanical 

and environmental stressors. This experimental investigation 

focused on the response of a UHPC beam subjected to concurrent 

inelastic flexural loading and 15 percent sodium chloride (NaCl) 

solution application. The results provided insight into the sustained 

robustness of UHPC structural members loaded beyond their 

tensile cracking strength. 

UHPC

Advances in the science of concrete materials led to the 

development of new cementitious materials, namely UHPC. 

As a class, these concretes tend to contain high cementitious 

materials contents, low water-to-cementitious materials ratios, 

Research, Development, and 

Technology

Turner-Fairbank Highway 

Research Center

6300 Georgetown Pike

McLean, VA 22101-2296

www.tfhrc.gov
2

compressive strengths above 21.7 ksi (150 MPa), 

and sustained tensile strength resulting from 

internal fiber reinforcement. Table 1 presents a 

select set of material properties for the type of 

UHPC investigated in this study.(1)

The exceptional durability of UHPC has been 

well documented. Of particular importance, 

UHPC contains no coarse aggregate, so it does 

not exhibit the early-age microcracking common 

to conventional concrete. This aspect, combined 

with the discontinuous pore structure in the 

homogeneous cementitious matrix, results in a 

concrete with extremely low permeability. 

The durability and sustained tensile capacity of 

UHPC present opportunities to reconsider common concepts in reinforced concrete structural 

design. For example, the tensile capacity of UHPC 

could eliminate the need for discrete mild steel 

reinforcement in some structural members, and 

its durability could reduce the cover required 

for any remaining reinforcement. These changes 

can facilitate slender, efficient designs heretofore considered impossible with conventional 

reinforced concrete. 

Durability of Cracked UHPC

Although UHPC’s impressive tensile capacity and 

durability have been assessed separately, prior 

studies have not investigated the robustness of a 

cracked UHPC section under simultaneous environmental and mechanical loading. Given the 

homogeneity and exceptionally low permeability 

of uncracked UHPC, it is anticipated that discrete 

structural cracking in UHPC components would 

necessarily increase the permeability. The ingress 

of liquids into the UHPC component along crack 

faces raises the possibility of steel fiber reinforcement degradation and a resulting loss of UHPC 

tensile capacity. 

Tensile behavior of UHPC stands in contrast to 

that of conventional concrete. The discrete steel 

fiber reinforcement included in UHPC components 

allows the concrete to maintain tensile capacity 

beyond cracking of the cementitious matrix. 

Studies have shown that tensile capacity can 

be maintained at or above the tensile cracking 

strength for as much as 10,000 microstrain.(2,4) 

The inelastic straining of the component is 

resisted by the fiber reinforcement, which bridges 

the tight, closely spaced cracks.

Test Program

To assess the tensile response of UHPC, this 

research focused on the cyclic loading of a UHPC 

beam and also included a series of static tests. 

One mild steel reinforced, rectangular cross 

section UHPC beam spanning 16 ft (4.88 m) was 

fabricated. This beam was subjected to cyclic 

structural loading in a four-point bending configuration. Figure 1 shows the loading arrangement. 

The magnitude of load surpassed the elastic limit 

of the UHPC cementitious matrix, thus causing a 

series of flexural cracks to occur near midspan. 

Table 1. UHPC material properties.

Property Value

Unit weight

156 lb/ft3

(2,500 kg/m3)

Modulus of elasticity

7,600 ksi 

(52,400 MPa)

Compressive strength

28 ksi 

(193 MPa)

Post-cracking 

tensile strength

1.0–1.5 ksi 

(6.9 to 10.3 MPa)

Chloride ion penetrability 

(ASTM C1202)(3) Negligible

Figure 1. Test setup for cyclic loading of beam.
3

The tensile face of the beam was subjected to 

continuous wetting via an open-cell sponge 

containing a 15 percent NaCl solution.

The flexural performance of the beam 

was monitored for 154 days, during which 

500,000  cycles of structural load were applied. 

The cyclic flexural response results are depicted

in figure  2. Afterward, the beam was loaded 

statically to flexural failure. Finally, a prism 

was cut from the bottom face of the beam near 

midspan and loaded in direct tension to failure. 

Each of these efforts was aimed at assessing 

the tensile performance of the UHPC after being 

subjected to structural fatigue loading in the 

presence of an environment that could potentially 

degrade the fiber reinforcement. Figure 3 shows 

the midspan of the beam following the application 

of all 500,000  cycles of structural load, and 

figure 4 is a photo of one of the flexural cracks at 

800x magnification. 

Conclusions 

Several conclusions were reached based on the 

results of this research. The simultaneous 

application of structural and environmental 

loading to a UHPC flexural member did not result 

in any apparent degradation of the member’s 

flexural capacity. 

It was concluded that tensile cracking of UHPC is 

indicative of cementitious matrix properties and 

Figure 3. Midspan of beam after 500,000 flexural 

cycles and 154 days.

Figure 4. 0.0002-inch (5-μm) wide flexural crack 

in the beam.

10

11

12

13

14

0 100000 200000 300000 400000 500000

Flexural Cycle

Lo

a

d-Dis

place

m

e

nt Slop

e

(k

N/mm)

57.1

62.8

68.5

74.2

79.9

Lo

a

d-Dis

place

m

e

nt Slop

e

(kip/inch)

Key: Flexural Cycles / Days Salt Solution Exposure

180k / 69 days 

380k / 141 days 

18k / 6.4 days 

1k / 0 days 

Figure 2. Flexural response of UHPC beam under combined loading.
4

Researchers—This study was completed by Ben Graybeal of the FHWA’s Turner-Fairbank 

Highway Research Center. Additional information can be gained by contacting him at

202-493-3122 or in the FHWA Office of Infrastructure Research and Development located at 

6300 Georgetown Pike, McLean, VA 22101.

Distribution—The unpublished report (PB2010-110331) covered in this TechBrief is being 

distributed through the National Technical Information Service, www.ntis.gov.

Availability—The report will be available in July 2010, and it can be obtained from the National 

Technical Information Service, www.ntis.gov.

Key Words—Ultra-high performance concrete, UHPC, Fiber-reinforced concrete, Bridges, 

Accelerated construction, Durable infrastructure systems, Permeability, and Tensile response.

Notice—This document is disseminated under the sponsorship of the U.S. Department of 

Transportation in the interest of information exchange. The U.S. Government assumes no liability 

for the use of the information contained in this document. The U.S. Government does not endorse 

products or manufacturers. Trademarks or manufacturers’ names appear in this TechBrief only 

because they are considered essential to the objective of the document.

Quality Assurance Statement—The Federal Highway Administration provides high-quality 

information to serve Government, industry, and the public in a manner that promotes public 

understanding. Standards and policies are used to ensure and maximize the quality, objectivity, 

utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its 

programs and processes to ensure continuous quality improvement.

July 2010 FHWA-HRT-10-055

HRDI-06/07-10(100)E

is not necessarily indicative of a plane wherein 

tensile failure of the section through fiber pullout 

will eventually occur. 

Additionally, the application of the structural and 

environmental loading was not observed to cause 

any local degradation of the fiber reinforcement 

bridging cracked planes. Ingress of NaCl solution 

along cracked planes was only observed to a 

depth of 0.12 inches (3 mm) on the side face of 

the beam and 0.2 inches (5 mm) on the tensile 

face of the beam. At locations where fiber pullout 

occurred across preexisting cracked planes, the 

fiber reinforcement did not show any visible signs 

of section loss or tensile failure.

Finally, UHPC can exhibit a wide range of 

ultimate tensile capacities within a small portion 

of an individual specimen. Cross sections loaded 

in uniaxial tension along a 7-inch (180-mm) 

length of an individual prism were observed to 

fail at 1.88 ksi (12.9 MPa), 2.30 ksi (15.8 MPa) , and 

2.63 ksi (18.1 MPa).

References

1. Graybeal, B.A. (2006). Material Property 

Characterization of Ultra-High Performance 

Concrete, Report No. FHWA-HRT-06-103, Federal 

Highway Administration, McLean, VA.

2. Graybeal, B.A. (2006). Structural Behavior of 

Ultra-High Performance Concrete Prestressed 

I-Girders, Report No. FHWA-HRT-06-115, Federal 

Highway Administration, McLean, VA.

3. ASTM. (1997). Standard Test Method for 

Electrical Indication of Concrete’s Ability to 

Resist Chloride Ion Penetration, American 

Society for Testing and Materials Standard 

Practice C1202, Philadelphia, PA.

4. Graybeal, B.A. (2009) Structural Behavior of 

a Prototype Ultra-High Performance Concrete 

Pi-Girder, NTIS Report PB2009-115495, 

National Technical Information Service, 

Springfield, VA.