Roadscience: The Chemistry of Pavement Forensics
by Tom Kuennen, Contributing Editor
nating corporate forensic pavement knowledge will help
assure exceptional performance in this area in the future.”
Acknowledging that staff turnover and retirements were
depleting the acquired engineering expertise of Texas
DOT, the writers in 2005 outlined creation of a knowledge database of rigid (portland cement concrete), and
later, in 2007, ﬂexible (bituminous concrete) pavements,
all accessible to Texas DOT employees via the Texas i-Way
learning content management system.
Tools for Detective Work
of Road Building
Wrong, and Why
Forensic Studies Give
Clues to Pavement Failure
hether the pavement is black or white, ﬂexible or rigid, asphalt or concrete, pavement
forensic testing is the key to preventing
future pavement failures in either paving medium.
In the lab or in the ﬁeld, engineers examine pavement
condition, cores or entire cut-out sections to ascertain
what went wrong, and why.
“Forensic pavement analysis is a core function of every
department of transportation,” say Paul E. Krugler, Carlos
M. Chang-Albitres and Robert L. Robideau, Texas Transportation Institute, in their paper Development of a Rigid Pavement
Forensics Knowledge Management System to Retain TxDOT Corporate
“Excellence in this technical area allows selection of
proper and most cost-effective rehabilitation options, with
potential monetary beneﬁts to the department of millions
of dollars annually,” they write. “Capturing and dissemi-
18 October 2012 Better Roads
Poor quality construction can occur due to a number of
complex and sometimes competing variables, reports the
Texas DOT, including reduced inspection stafﬁng, employee turnover, variability of inspectors’ and project managers’ experience levels, incompatibilities between new
admixtures and construction materials, implementation
of new technologies and construction methods, environmental constraints, recycled materials and other issues
unforeseen during design and construction phases.
“To prevent, and to reduce the probability of premature
pavement failures and poor long-term pavement performance, the root causes of these problems have to be
identiﬁed,” Texas DOT says in its Pavement Design Guide. “In
conducting forensic studies, a thorough review and analysis of existing quality construction records and tests, nondestructive testing like ground penetrating radar (GPR)
and the falling weight deﬂectometer (FWD) are essential
to identify problematic areas and probable causes.”
“When a pavement fails earlier than expected – with
early cracking or rutting – we conduct forensic investigations to determine why that happened so soon,” says
Timothy R. Clyne, P.E., MnROAD forensic engineer for
Minnesota DOT’s MnROAD pavement test facility.
MnROAD – a full-scale accelerated pavement test facility
– tests pavement materials, structural designs and construction techniques. It’s unique in that in addition to a
low-volume roadway test track that simulates conditions
on rural roads, it includes an actual test section of I-94
that carries live Interstate trafﬁc.
“We will do a forensic investigation on good roads to
ﬁnd out what we did right, or what were the conditions
that made things go so well with that section,” Clyne says.
“But most of the time our forensic investigations are on
early failures.” MnROAD also will conduct forensic investigations for pavements throughout the state, either for
Minnesota DOT or local agencies.