05 - Effective Design and Operation of Concrete Infrastructure
Submitting InstitutionsHeriot-Watt University,
University of Edinburgh
Unit of AssessmentGeneral Engineering
Summary Impact TypeTechnological
Research Subject Area(s)
Engineering: Civil Engineering
Summary of the impact
ERPE research has made major impacts on the design and operation of
concrete infrastructure through design, corrosion investigation/residual
life prediction and non-destructive testing (NDT). New interpretations of
ground penetrating radar (GPR) data have impacted international practice
through: the American Concrete Institute (ACI) document on NDT of
Concrete, ACI 228.2r2013; fib Model Code 2010, ISBN:978-3-433-03061-5; a
corrosion monitoring device; and "GprMax", the world's most widely used
and acclaimed GPR freeware.
The financial impact of the underpinning ERPE research is estimated at
£100M p.a. on infrastructure maintenance savings worldwide.
The ERPE Concrete and NDT Group were all in post throughout the period
unless stated otherwise: Professors Forde, McCarter, Usmani and Chrisp;
Senior Lecturers Cairns and Giannopoulos; Lecturers Hardy and Law (to
2010); Research Fellow Starrs. In addition: PDRA's Blewett and Ezirim; and
many PhDs (now employed by the industry): Diamante (2008 to Sensors &
Software, Canada), Clark (now CH2MHill, Dubai); Du; Gordon (now Mouchel);
Padaratz and Martin (now Arup) were all previous Group members and
contributed to its developments. This group has conducted research into
concrete deterioration and NDT investigation and monitoring with these key
Reinforcing Steel design and corrosion monitoring.
ERPE research over the last decade addressed a range of technical issues
within the topic of bond between reinforcement and concrete. This work
addressed fundamental modelling of behaviour , new reinforcing
materials, serviceability performance, strength in new construction and
residual strength and degradation of deteriorating concrete structures. Of
particular recent consequence has been advances in identifying
corrosion-damaged structures and on fusion bonded epoxy coated
reinforcement. The field work aspect of this was followed up by McCarter
for a corrosion monitoring instrument  patent application published in
2011 as WO2011 048378 A2
Quantification of NDT Test Interpretations; instrumentation and
ERPE quantified in 1995, for the first time, the accuracy of both
electromagnetic GPR and stress wave impact-echo NDT identification of
shallowest defects — related to signal wavelength . New insights into
electromagnetic wave impulse radar GPR propagation through concrete were
established theoretically and verified experimentally, linking antenna
centre frequency in air to wave propagation through concrete. The research
clarified the relationship between antenna centre frequency and shallowest
detectable target. Parallel work on stress wave propagation has brought
new insights into impact echo testing of concrete. Previously, the choice
of impact hammer excitation of concrete was fairly arbitrary — this work
has related hammer size to signal wavelength and depth of first detectable
target, funded under four Highways Agency (HA) Contracts (totalling
£392k). This provided the key input to ACI document 228.2r-2013 — see [2,
Testing and monitoring site measurements.
Further research into non-destructive evaluation and monitoring of
concrete deterioration from 1995 developed marine and roadside test-sites
under the auspices of the Transport and Road Research Laboratory and
Transport Scotland. These sites allowed monitoring of concrete at near
full-scale under natural environmental action. The marine test-site
provided a unique database for chloride ingress (diffusivity) into
concrete as chloride profiling has been continuing for almost twenty
years. Through EPSRC (GR/L55810, £157k) and Transport Scotland; (£105k),
an embeddable sensor system was developed which enables discretized
electrical impedance (and temperature) measurements to be obtained within
the concrete cover-zone. Such measurements are directly related to those
properties of concrete which promote the ingress of water and water
containing deleterious ionic species, hence durability and performance [4,
5] and this was extended within Grants EP/G025096 (£361k) and EP/I005846
(£100k). The marine test-site was used to trial a remote interrogation
system whereby the sensor system could be accessed from the office
setting. This sensor array exploitation is now licensed to Amphora NDT.
Ground Penetrating Radar.
The theoretical and numerical focussed research on GPR modelling  is
now well-established in practice for infrastructure monitoring and
assessment with applications ranging from concrete and masonry
infrastructure through to mine detection and ice cap probing. ERPE are
currently enabling easy access to the software (www.GprMax.org)
not only in the UK, but also to internationally based practitioners and
researchers and to extending application to other areas, e.g. abandoned
References to the research
References identified with * are those which best indicate the quality of
the underpinning research.
 Cairns, J., Du, Y. and Law, D.W. "Structural Performance of
Corrosion-Damaged Concrete Beams", ICE Magazine of Concrete
Research, Vol. 60, No. 5, pp. 359-370, 2008. DOI:10.1680/macr.2007.00102
. Google Scholar (GS) 16 citations.
Guidance provided in Table 6.1-4 of the fib Model Code 2010 is based on
this investigation of reinforced concrete beams with up to 8% loss of
rebar cross section due to corrosion.
 Padaratz, I.J. and Forde, M.C. "A Theoretical Evaluation of
Impulse Radar Wave Propagation through Concrete", Journal of
Non-Destructive Testing & Evaluation, Vol. 12, pp. 9-32, 1995. DoI: 10.1080/10589759508952833
. GS 21 citations.
This has brought new insights into radar propagation through concrete and
heavily influenced Section 3.8 of ACI 228.2r-2013 and the data forms the
basis of Table 3.8.2 in ACI 228.2r-2013.
 Martin, J., Hardy, M.S.A., Usmani, A.S. and Forde, M.C. "Accuracy
Of NDE In Bridge Assessment", Engineering Structures, Vol 20, No.
11, pp. 979-984, 1998.
. GS 23 citations.
This has brought new insights into impact echo testing hammer excitation
of concrete and heavily influenced Section 3.2 of ACI 228.2r-2013 and the
data forms the basis of Table 220.127.116.11 in ACI 228.2r-2013.
*McCarter, W.J., Emerson, M. and Ezrim, H.,
"Properties Of Concrete
In The Cover Zone: Developments In Monitoring Techniques"
Magazine of Concrete Research, Vol. 47, No. 172, pp. 243-251, 1995. DOI: 10.1680/macr.1918.104.22.168
GS 46 citations.
This represents the initial development of an embeddable conductivity array
to study water and ionic movement within cover-zone concrete. It is this
cover-zone which plays an important role in protecting the steel
reinforcement and is regarded as critical with regard to the durability of
reinforced-concrete and its long-term performance.
*McCarter, W.J., Chrisp, T.M., Starrs, G. and Blewett, J., "Characterisation
And Monitoring Of Cement-Based Systems Using Intrinsic Electrical
Property Measurements", Cement and Concrete Research, Vol. 33, pp.
197-206, 2003. DOI: 10.1016/S0008-8846(02)00824-4.
GS 43 citations.
The research highlights the use of electrical property measurements to
study, for example, the hydration and hydration kinetics of cementitious
materials and the response of the concrete cover-zone to cyclic wetting
* Giannopoulos, A., "Modelling Ground Penetrating Radar By GprMax",
Construction and Building Materials, Vol. 19, pp. 755-762, 2005. DOI: 10.1016/j.conbuildmat.2005.06.007.
GS 160 citations.
This summarises more than 10 years research into a solver for GPR: GprMax,
which is now the most widely used GPR modelling software and an industry
Details of the impact
The deterioration of concrete structures is of world-wide concern. In the
UK, the total construction industry investment in 1995 was £52 billion,
with 50% spent on maintenance, repair etc., representing a threefold
increase over the previous 14 years. The £28M Birmingham Midlands link
motorway required £45M of repairs between 1972-89 and then required a
further £120 million investment up to 2004. In continental Europe,
structural repairs cost €1.4 billion p.a. In 1998, US estimated a
five-year investment of $1.3 trillion to reinstate roads, bridges and
other infrastructure systems to good serviceable life. This had increased,
by 2005, to $1.6 trillion, as in excess of 40% of 500,000 highway bridges
are rated as structurally deficient requiring $100 billion to eliminate
the bridge backlog.
The ERPE work on Non Destructive Testing (NDT) has been accepted
internationally by the American Concrete Institute (ACI 228-2r-2013), and
by international manufacturers such as Sensors and Software who use GPR
max software to design their new generation of GPR antennas. This has
brought new insights into electromagnetic wave impulse radar GPR
propagation through concrete by linking antenna centre frequency in air to
wave propagation through concrete. It has clarified the relationship
between antenna centre frequency and shallowest detectable target. This
has heavily influenced Section 3.8 of ACI 228.2r-2013 and the data forms
the basis of associated Table 3.8.2. The work on stress wave propagation
has brought new insights into impact echo testing of concrete. Previously
the choice of impact hammer excitation of concrete was fairly arbitrary —
this work has related hammer size to signal wavelength and depth of first
detectable target. ERPE research has changed industry thinking by heavily
influencing Section 3.2 of ACI 228.2r-2013 and our data forms the basis of
"As Principal and Manager of our international group NDT practice in
Dynasty Group I can verify that the ERPE work led by Forde has
established new understandings of the accuracy and effectiveness of NDT
techniques such as radar testing of concrete, masonry and railway
trackbed, plus impact echo testing. This highly innovative world leading
work has influenced the technical success of our own company and has
achieved international impact through its inclusion in the American
Concrete Institute's ACI 228.2r-2013 "Report on Nondestructive
Test Methods for Evaluation of Concrete in Structures". Forde led the
drafting of this world standard in Civil Engineering concrete NDT over 8
years and I was a voting member of the ACI 228 Committee."
Principal, Dynasty Group, USA [S1].
The ERPE work led by McCarter developed the use of electrical property
measurements to study the hydration and hydration kinetics of cementitious
materials and the response of the concrete cover-zone to cyclic wetting
and drying key areas when assessing concrete corrosion. The field
implementation of this work of this was implemented by McCarter when he
developed a corrosion monitoring  instrument: UK Patent application
WO2011 048378 A2 which was licensed in 2013 to Amphora NDT Ltd (sold under
the trade name Septopod:
and has recently been installed on the Hangzhou Bay Bridge in China [S5].
"I can confirm that the long-term leading research on the performance
of concrete in extreme marine environments is of major importance to the
international bridge community. This work, partially funded by us for
20+ years has led to a patent pending NDT instrument manufactured and
marketed by Amphora NDT, with sales in China. Further development of the
sensor array & retrofitting in a variety of Trunk Road environments
has expanded the applicability of the technology & provides
confidence of ongoing structural performance. This is an excellent
example of research fulfilling the needs of bridge owners and providing
an instrument to monitor important on-site durability issues worldwide"
— Network Bridges Manager, Transport Scotland [S2].
The ERPE radar (GPR) modelling work  over 10 years led Giannopoulos to
write the world's most widely used Finite Difference Time Domain (FDTD)
forward modelling program (some 4,000 downloads) which has had a worldwide
impact on improving both the accuracy of interpretation of radar surveys
by service providers and also on the manufacturers design of antenna
"As CEO of Sensors & Software, the world's leading manufacturer of
GPR (ground penetrating radar) equipment, I can confirm that the world's
leading GPR modelling software is GprMax which is used by industry and
researchers worldwide. Here we use it for modelling to help us improve
our antennae for the worldwide market and we confidently state that it
is increasing our turnover and profit." Senior Manager Sensors &
Software Inc, Canada [S3].
Concrete design research in ERPE, has made a significant contribution to
the fib (fédération internationale du béton) Model Code (MC2010), (fib
2013) [Ernst & Sohn, Berlin, Oct 2013, ISBN: 978-3-433-03061-5 and http://www.fib-international.org/model-code-2010-final-draft-volume-1]
Cairns, as convenor of Task Group 4.5 (TG4.5) `Bond Models', was
responsible for drafting Section 6.1 `Bond of embedded reinforcement' and
sub-sections 22.214.171.124-6 within `Detailing'. The previous version of this
fib Model Code formed the basis for Eurocode 2 (http://www.concretecentre.com/codes__standards/eurocodes/eurocode_2.aspx),
the design standard for Europe. These Model Codes provide industry rules
which assist them today in the design of safe, constructible and economic
concrete structures. ERPE innovations include:
- Modified design rules to cater for: (a) new high performance concrete
(C100/125); (b) new materials and technologies with differing bond and
anchorage capabilities — e.g. fusion bonded epoxy coated reinforcement
and headed bars.
- Guidance has been introduced on the load carrying capacity of concrete
structures following a period of deterioration or following repair.
- Inconsistencies in MC90 design rules have been addressed, e.g.
statistical analysis has demonstrated an insignificant difference in
bond strength between lapped joints and of anchorages, but design rules
in MC90 treat laps and anchorages as different. MC2010 has resolved
"As a colleague on fib Task Group 4.5 (TG4.5) `Bond Models' code of
practice I confirm that Cairns has been responsible for a major review
and updating the technical content covering the bond between embedded
reinforcement and concrete and that those revisions now provide a more
rational evidence based approach. He is also leading production of a fib
Bulletin which records the rationale and evidence for these revisions
which will be published in 2014." Italian TG4.5 committee member
Other documents, based on ERPE research, are current and are still
impacting international industrial practice today:
BA86/06 Advice Notes on the Non-Destructive Testing of Highway
Structures, Highways Agency (HA), Design Manual for Roads & Bridges,
Vol. 3, Section 1, Part 7, 2006, 247 pp.
IAEA (2002) Guidebook on Nondestructive Testing of Concrete Structures,
IAEA-TCS-17, Austria, Sept 2002, 231 pp.
Sources to corroborate the impact
[S1] Principal and Manager of NDT, Dynasty Group Inc., see comments
included in Section 4.
[S2] Network Bridges Manager, Transport Scotland, see comments included
in Section 4.
[S3] Senior Manager, Sensors & Software Inc. , see comments included
in Section 4.
[S4] Member of the Task Group 4.5 Committee, see comments included in
[S5] Deputy Chair of Chinese construction committees can confirm the
sensor system installation on Hangzhou Bay Bridge in China.