Ultrahigh volume fly ash concrete (UHVFAC) for highway infrastructure
Focus Area
Waste Management/Recycling/Brownfields
Subcommittee
Environmental Process, Natural Resources
Status
Archived
Cost
$250k-$499k
Timeframe
2-3 years
Research Idea Scope
This research project will evaluate the feasibility, cost-effectiveness
and benefits of using ultrahigh volume fly ash concrete (UHVFAC) for the
construction and maintenance of highway structures and pavements. The
environmentally friendly binder is envisioned to consist of either fly ashes
with high-lime content and low loss-on-ignition (LOI), or “below grade” fly
ashes (e.g., with relatively high LOI) mixed with nano-scale and micro-scale
materials. Fly ashes readily available
will be assessed and utilized. The “green” binders will replace cement
as binder by at least 75% and up to 100%, without the need for activator (e.g.,
alkalis or heat treatment). This technology takes the advantage of technical
breakthroughs found in the recent advances in the 100% fly ash concrete and in
the nano-/micro- modification of cementitious materials. The concept of this
technology has been preliminarily proven in the Corrosion & Sustainable
Infrastructure Lab (CSIL) at Montana State University.
This research will address key technical challenges
associated with utilizing “green” binders in concrete and relax the restriction
on using fly ashes in concrete without sacrificing quality and long-term
performance of the concrete. The proposed activities are divided into four
parts: (1) synthesizing DOT high volume fly ash binder and concrete, based on
the survey of current practices, DOT user requirements, and materials
availability; (2) optimizing mix designs of UHVFAC modified with
nano-/micro-materials, recycled concrete aggregate or demolition waste,
ordinary Portland cement, and other additives; (3) assessing the properties and
performance of UHVFAC for pavement or structural applications (workability,
strength and durability properties); and (4) assessing the cost-effectiveness
and benefits of UHVFAC for highway construction or maintenance.
Urgency and Payoff
This research will greatly contribute the DOT strategic
objectives, by improving the cost-effectiveness, durability, reliability and
sustainability of the highway infrastructure. Considering the cost savings in
transportation and waste disposal, the use of recycled materials and industrial
byproducts can provide viable, cost-effective options for highway applications.
This research is much needed especially in light of the aging DOT highway
infrastructure and the need to minimize the environmental toll and carbon
footprint of concrete construction and maintenance activities. It would provide
a cost-competitive, commercially viable approach to extending the service life
and sustainability of highway concrete infrastructure. First, this research
will remove fly ashes from waste stream and/or add value to its use in
construction projects. Fly ashes are byproducts of coal combustion in the
generation of electricity, and their expanded use (in place of cement as
binder) can translate to cost and energy savings and reduce greenhouse gas
emissions and landfill waste. Second, this research will help DOT to develop
durable and sustainable concrete materials for highway applications.
While there have been increasing usage of recycled materials
and industrial byproducts in concrete and a growing body of positive highway
user experience, a study to focus on the specific DOT constraints and needs is
much needed and timely. Many states have allowed the use of
performance-specified (ASTM C1157) cements that contain fly ash. Yet, the
expanded use of “below-grade” fly ashes is hindered by some unsolved problems,
which are resulted from the lack of knowledge relating their fineness,
mineralogy and chemistry to performance.
Submitted
10/08/2013