Infrasense Present Research at ASNT Bridge and Highway Conference in New York

The International American Society for Nondestructive Testing (ASNT) recently
held their NDE/NDT For Highways and Bridges: Structural Materials Technology
Conference in New York City (August 21-24), and Infrasense engineers played a
key role in presenting recent bridge testing research and practice. The biennial
conference aims to, "promote the exchange of information between national
and international researchers, practitioners and infrastructure owners on the
application of Nondestructive Evaluation (NDE) and Nondestructive Testing
(NDT) technologies for the condition assessment of highway bridge and
pavement infrastructure." This year's conference was attended by nearly 200
people including members of universities, research institutions, transportation
agencies, and consulting firms. This marks the 6th time Infrasense has attended
and contributed with technical papers, presentations and an exhibit. This year
Infrasense staff are primary authors on two conference papers, and a secondary
author on a third conference paper.

In the area of bridge deck assessment, Adam Carmichael of Infrasense
presented the results of an independent evaluation of network-level bridge
deck condition assessments in Minnesota. MnDOT has contracted out NDT
scanning on 100 bridge decks throughout Districts 1, 3, 6, and metro areas.
Most of the work was carried out with ground penetrating radar (GPR), and was
supplemented with the use of infrared thermography (IR) on a select number of
decks. The purpose of this work was to determine the degree of unsound
concrete in each deck so that appropriate maintenance and rehabilitation
measures could be taken to maximize the benefit to users for a given budget.
As part of this process, MnDOT commissioned an independent study by EVS,
Inc. to review cost, accuracy, and usefulness of these NDT methods with respect
to their estimation of the actual extent of bridge deck repair. The repair work
on 12 of the bridge decks was evaluated. This evaluation found the GPR and IR
results to be within 3.5%-4% of actual repair quantities on average.

The latest research developments into the detection of deck deterioration were
presented by Nicole Martino of Northeastern University, with contributions from
Dr. Maser of Infrasense, who serves as a consultant to Northeastern in the field
of nondestructive testing in concrete bridge decks. The goal of the research has
been to establish a clearer connection between the data generated by the GPR
equipment and the different aspects and stages of bridge deck deterioration. To
achieve this goal, a full battery of testing was performed on in-service
structures, controlled slabs specifically cast for corrosion testing, and slabs
extracted from in-service structures during deck replacement projects. The
research has already yielded some significant results. Preliminary results have
revealed that the spatial correlation between GPR and HCP is 90%, indicating the
ability of GPR to detect corrosion activity in bridge decks. Additionally, the
spatial correlation between GPR and IE testing for delimitations is 79%.

Practical applications of NDE technology for bridge load rating were presented
by Dr. Maser of Infrasense. Load rating is carried out on all bridge structures to
ensure that they have the capacity to support the expected vehicular loads, or
to appropriately restrict the vehicular loading on older and/or distressed
structures by posting load limits. For many of these older structures, including
culverts, concrete and stone arches, and precast girder bridges, design or as-
built plans are no longer available to serve as a reference for the load rating
analysis calculations. In these situations, NDE methods are often useful to fill in
such missing data as element thickness, depth of overburden (culverts and
arches), rebar depth and spacing, and estimated concrete strength. Over the
past few years, MassDOT has used these techniques to support load ratings on
a large number of structures. In his presentation, Dr. Maser discussed the types
of structures that have been investigated, the NDE methods used, the data that
was obtained and the methods of analysis, and the resulting information
generated for the load rating process.

About Infrasense, Inc.

Since 1987, Infrasense, Inc. has applied the most current technologies to the
most difficult challenges in subsurface scanning. Infrasense’s engineers are
able to nondestructively extract critical information from a diverse range of
structures. The firm has conducted research to advance the field of subsurface
detection, while also providing valuable information to clients across the
country. Learn more about Infrasense, Inc. and its services at
http://www.infrasense.com.