Page 11 - July-Aug 2019 Vol37 No2
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Backfill and Road Base Applications Tested from the perspective of demolition Values obtained from the evaluation of
During this particular research project, contractors, concrete suppliers and the physical and mechanical properties
developers. This not only encourages the of RCA were compared against the values
several different applications were tested use of construction and demolition waste, obtained from the same evaluation
according to Tennessee Department of but also puts a tighter regulation on the process conducted on virgin aggregate.
Transportation (TDOT) specifications market of recycled aggregate. The results showed that Recycled
in regard to backfill and road base. In Concrete Aggregate has higher absorption
general, the quality of recycled aggregate The results of the case study and survey capacity due to the mortar adhered on
depends on the loading and exposure also were used to determine the feasibility the surface, higher abrasion loss, high
conditions of the demolished structures. of developing a more diverse market crushing value, and soundness loss which
for recycled aggregates. The potential could be attributed to previous exposure
Therefore, the experimental program for demolition wastes to be used in the to weathering and loading.
was focused on the evaluation of physical production of new concrete products has Thorough Inspection for TDOT Standards
and mechanical properties of the recycled been thoroughly studied in academic
aggregate. In addition, concrete properties settings and successfully demonstrated in Thus, the recommended strategy for
produced with fine and coarse recycled the field via test cases. procuring RCA that meets TDOT’s
aggregate were evaluated. standards and specifications relies
In rapidly growing metropolitan heavily on the inspection of the products,
The road base mixes were prepared areas hosting a robust combination of installation of cameras and raised platforms,
with 100 percent recycled aggregates demolition activities and new construction with certified aggregate technicians
and the results were compared to that of projects, symbiotic relationships can exist thoroughly monitoring the crushing,
TDOT Grade D base stone and a 50/50 between crushing companies and materials washing, and dumping practices within
blend of virgin grade D and RCA base; by producers with proper coordination these construction and demolition facilities.
comparing two variables: size distribution and infrastructure. Recycled aggregates
and proctor density measuring the max are composed of the rubble from the Metro Nashville Public Works would like
dry density in the lab at optimum moisture demolition of buildings roads, and other to thank MTSU’s Dr. Brown and Vulcan’s
content. sources such as returned concrete. Gabrielson for their active participation
A Market for Recycled Aggregate in this research summary and product
Although unlicensed landfills are known demonstration. Sustainable practices
A series of applications for RCA to be one destination for the demolition and resources cannot be furthered in the
were identified and local C & D landfills waste, the remainder arrives at either construction industry without these types
were surveyed during this testing municipal or private facilities that have the of valuable partnerships.
demonstration. Incentives encouraging the capacity to crush the material into either
production of RCA must be considered graded or ungraded material.
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