Intelligent compaction (IC)
has emerged as a breakthrough technology that utilizes advanced sensing, data
transmission, and control systems to optimize asphalt pavement compaction
quality and efficiency.
Compaction is considered
one of the most important processes in pavement and asphalt roadway surface
construction as it can provide good long-term performance. The densification of
the various layer materials achieved through compaction gives them the strength
and stiffness necessary to withstand heavy traffic loading and some of the
damaging effects of the environment. The conventional rolling equipment and
techniques for achieving the target levels of compaction have worked reasonably
well over the years; however, they have not been without their difficulties.
The typical problems associated include non-uniformity derived from variability
in the materials (particularly in the natural soil), poor control of moisture
content in the underlying layers, low or non-uniform temperatures in the
hot-mix asphalt (HMA) layer, poorly compacted longitudinal joints, and a lack
of tools that provide feedback to the roller operator so that the roller
pattern can be continuously achieved.
The inherent flaws in
conventional compaction practices have various implications, including
diminished efficiency, increased costs, compromised pavement performance,
shortened road service life, and augmented expenses for maintenance and repair
in road construction projects. Over the past years, there have been several
major innovations in technology for highway pavement construction that has
greatly revolutionize pavement construction. One of these innovations,
intelligent compaction, is intended to address some of the problems associated
with conventional compaction methods. Intelligent Compaction (IC) technology
has emerged as a viable solution that can improve the durability and compaction
quality of pavements. Moreover, it enables accurate quality monitoring and
timely detection of defects, thus resulting in saved construction time.
IC technology is an
advanced compaction that utilizes rollers equipped with state-of-the-art
measurement systems, including accelerometers, global positioning systems
(GPS), infrared thermometers, feedback controls, and on-board display and
reporting systems. By deploying these technologies, a comprehensive and
data-driven compaction control approach is achieved, shifting compaction
quality management from post-inspection to a proactive methodology. The rollers
used for IC are basically the same as their conventional counterparts. The
primary difference between the IC rollers and conventional rollers is the
instrumentation added to identify roller location, measure/control the process,
and display and document the level of compaction. With some differences to
account for the type of material being compacted, this instrumentation is
basically the same for rollers that are designed to compact unbound/subsurface
materials (subgrade soil, subbase, and base) and the asphalt pavement surface
layers (binder and wearing courses).
IC roller is distinguished
by several key technical features. The vibratory roller is equipped with an
accelerometer mounted on the frame of the roller near the roller drum to
measure frequency, amplitude and acceleration of rollers; infrared temperature
sensor installed on the rear and front drum to record the surface temperature
of the mat in the direction of operation, while high-precision global
positioning system to record the roller drum spatial position and map the
roller coverage, which is then displayed to the roller operator in real time on
the vehicle display monitor. The measurement results of IC are presented as a
colour-coded map (Red, yellow, green and blue colour patches indicating
different compaction measurement value).
One of the essential
aspects of IC rollers is collecting, processing, and evaluating measurements in
real-time. It allows the roller operator to view a colour-coded map in
real-time that depicts the connection between roller location, number of
passes, cumulative compaction effort, and material reaction. Feedback controls
can use this information to modify the drum’s force, and to amend the frequency
in real-time. These accommodations allow for improved performance and power.
Furthermore, the IC roller’s display alerts the operator when it achieves the
required compaction level. With this, it will avoid needless passes. If the
system detects trouble zones, it will signal the operator when additional
roller passes would not achieve the target compaction. It will then document
the matters for further investigation.
By incorporating advanced
sensing, control, and monitoring systems, IC offers several advantages over
traditional compaction methods. Real-time feedback enables operators to make
precise adjustments, ensuring optimal compaction while minimizing risks of
over-compaction or inadequate compaction. Additionally, the ability to collect
comprehensive data on compaction uniformity enhances quality control and leads
to improved pavement performance and an extended service life. Compared to
traditional practices reliant on manual operation and periodic sampling, IC
represents a paradigm shift toward continuous, real-time management of the
entire compaction process from start to finish. The most significant improvement,
using the IC technology, is the reduced material variability. IC equipment
allows contractors to more closely monitor the stiffness of the material so
that there is less variability in the end result. Over the long run, lower
variability will result in better pavement performance and intended service
life with reduced maintenance and repair costs.
IC increases productivity
and efficiency of the compaction process as the number of necessary roller
passes and the time of compaction is reduced. Fewer passes to achieve the
correct compaction level minimizes fuel use and equipment wear and tear. IC
improves operator awareness of real-time compaction (soils), temperature
(asphalt), pass count data, and early detection of trouble areas, and more. IC
technologies can be especially beneficial to maintain consistent rolling
patterns under lower visibility conditions, such as night paving operations.
Data from IC operation, along with GPS coordinates of compaction activity, can
be downloaded into construction quality databases and stored electronically by
the contractor for future reference.
While all the leading manufacturers of soil and asphalt compactors offers IC technology as an inbuilt feature in their equipment, most existing conventional vibratory rollers can be easily converted to an IC roller using a retrofit kit.