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Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
4
Figure 3. Bottom Ash
for large volume uses like structural fills. An evaluation of
groundwater conditions, applicable state test procedures, water
quality standards, and proper construction are all necessary
considerations in ensuring a safe final product. There are
several leaching tests and currently U.S. Environmental
Protection Agency is nearing publication of new leaching
standard appropriate for beneficial use application of CCPs and
other similar materials (Kosson et al. 2002). U.S. EPA is
currently reviewing its rules regarding beneficial use of CCPs.
4 ASSESSMENT OF SUSTAINABILITY
Assessment of sustainability involves the life cycle assessment
(LCA) of the environmental benefits and the life cycle cost
analysis (LCCA). LCA involves determining a variety of
sustainability metrics (e.g., energy consumption, GHG
emissions, water use, hazardous waste generation, etc.)
associated with production of construction materials, their
transportation to the construction site, and construction itself.
These determinations can be made using available database
programs such as the PaLATE model (Horvarth, 2004). LCCA
evaluates life cycle cost of design alternatives including the
initial construction and maintenance based on service life. A
convenient computer code named RealCost can be used for this
purpose (FHWA 2004). Service life is a crucial part of this
analysis and materials with higher modulus typically result in a
longer service life for the same thickness of pavement layers.
Examples of LCA and LCCA are available (Lee et al. 2011).
A rating system for sustainable highway construction, named
Building Environmentally and Economically Sustainable
Transportation
-
Infrastructure
-
Highways, BE
2
ST
-
in
-
Highways
TM
was developed to provide a quantitative methodology for rating
the benefits of sustainable highway construction (Lee et al.
2011). The methodology is grounded in quantitative and
auditable metrics so that a transparent linkage exists between
the project rating and the sustainable practices employed in
construction. This rating system can be employed by the
highway construction industry and agencies to quantitatively
evaluate sustainable practices and to incorporate sustainable
elements into projects.
The BE
2
ST
-
in
-
Highways
TM
system evaluates sustainability
of a highway project in terms of a quantitative difference
between a reference design and proposed alternative design(s).
Thus, the reference highway design must be defined
realistically. A conventional design approach in which
sustainability concepts are not incorporated explicitly can be
used as a reference design. The analysis assumes that the
service life of conventional and alternative designs can be based
on an international roughness index (IRI) prediction made with
the Mechanistic Empirical Pavement Design Guide (M
-
EPDG)
program (NCHRP)
and that rehabilitation occurs at the end of
the predicted service life.
5 CONCLUSIONS
1. It is imperative that industry-wide sustainable construction
practices be adopted and recycled materials play a significant
role in earthen construction where large quantities of materials
are used such as in roadway construction.
2. Benefits of recycled materials include reduction in
greenhouse gas emissions, energy, natural resources, and cost.
4. Wise use of recycled materials may create longer lasting
structures and reduction in cost.
5. Conducting quantitative analyses using appropriate
sustainability metrics to assess alternatives involving recycled
materials is imperative.
6 ACKNOWLEDGEMENTS
The information and ideas presented were developed through
numerous projects involving many associates and students, too
long to list here. Prof. Craig H. Benson and the Recycled
Materials Resource Center are acknowledged.
7 REFERENCES
ASTM. 2011. D7762 Standard
Practice for Design of Stabilization of
Soil and Soil-Like Materials with Self-Cementing Fly Ash
.
”
Bozyurt, O., Tinjum, J. M., Son, Y. H., Edil, T. B. and Benson, C. H.
2012. Resilient modulus of recycled asphalt pavement and recycled
concrete aggregate. GeoCongress 2012, ASCE, GSP No. 225,
Oakland, CA, 3901-3910.
Edil, T.B., Acosta, A.A. and Benson, C.H. 2006. Stabilizing soft fine-
grained soils with fly ash. ASCE
Journal of Materials in Civil
Engineering
, 18 (2), 283-294.
Edil, T.B, Tinjum, J.M. and Benson, C.H. 2012. Recycled Unbound
Materials. TPF-5 (129) Final Report. MNDOT, MN, USA.
FHWA. 2008. User Guideline for Byproducts and Secondary Use
Materials in Pavement Construction. FHWA-RD-97-148,VA, USA.
FHWA. 2004. Life Cycle Analysis RealCost User Manual. VA, U.S.A.
Guthrie, S. W., Cooley, D., and Eggett, D. L. 2007. Effects of reclaimed
asphalt pavement on mechanical properties of base m
aterials.”
Jrnl.
Transportation Research Board, NRC, No.2005, Wash. D.C., 44-52
Horvath, A.
Pavement Life-cycle Assessment Tool for Environmental
and Economic Effects (PaLATE) User Manual
.
Kosson D. S., Van der Sloot, H. A., Sanchez, F.,Garrabrants, A. C.
2002. An integrated framework for revaluating leaching in waste
management and utilization of secondary materials. Env. Eng. Sci.
19, 159
–
204.
Lee, J. C., Edil, T. B., Benson, C. H. and Tinjum, J. M. 2011.
Evaluation of variables affecting sustainable highway design using
the BE
2
ST-IN-HIGHWAYS
TM
System
,”
Jrnl. Transportation
Research Board
, NRC, No. 2233, Wash. D. C., 178-186.
Nokkaew, K., Tinjum, and J.M., Benson, C. H. 2012
. “Hydraulic
Properties of Recycled Asphalt Pavement and Recycled Concrete
Aggregate,”
GeoCongress, ASCE, Oakland, CA, 1476-1485.
