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Title:
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Use of accelerated aging to predict behavior of recycled materials in concrete pavements. Physical and environmental comparison of laboratory-aged samples with field pavements
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Author(s):
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Sloot, H.A. van der; Eighmy, T.T.; Cook, R.A.; Gress, D.L.; Coviello, A.; Spear, J.C.M.; Hover, K.; Pinto, R.; Hobbs, S.; Kosson, D.S.; Sanchez, F.; Korhonen, C.; Simon, M.
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Published by:
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Publication date:
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ECN
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1-11-2002
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ECN report number:
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Document type:
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ECN-RX--02-061
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Article (scientific)
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Number of pages:
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11
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Published in: Transportation Research Record 1792, Paper No. 02-2452, p. 118-128 (), , , Vol., p.-.
Abstract:
Future behavior of recycled materials in highway applications is oftendifficult to predict. Accelerated aging is one means of exploring the
long-term physical and environmental performance. Coal fly ash (CFA),
routinely used as a cementitious replacement in portland cement concrete
pavement, was selected as a model system in an accelerated aging approach.
US-20 near Fort Dodge, Iowa, was used as a source of field-aged pavement
slab material and concrete mixture proportions. This pavement, constructed
in 1987, experienced early failure and distress. The role of CFA, if
any, in the failure is not known. Three types of accelerated aging treatments
were chosen and applied on laboratory prisms made with the US-20 mixture
proportions: arrhenius ageing (AA), cyclic loading, and freeeze-thaw
exposure. Phycial and environmental response variables were used to
examine the pavement slab and the aged laboratory prisms. The aging
protocol affected both physical and chemical properties of the monoliths.
It took about 9 months of elapsed time to age specimens to an equivalent
age of about 4 years. The equivalent ages matched well with the time
frame seen in the field for the onset of early distress. Most response
variables for the aged laboratory prisms and the field samples were
similar, suggesting that the aging method reasonably produced a pavement
of similar age and distress. The AA treatment produced an unexpected
loss of strength, suggesting that the accelerated aging promoted the
onset of a deleterious reaction. Distinguishing the source of trace
metals in leachates was difficult, for all components (CFA, aggregates,
cement) had similar elemental compositions and leachability. The use
of both physical and environmental response variables showed linkages
between compressive strength, microcracking, fine pore structure, Cl
diffusive leaching (efflux related to road slating that increases the
concentration of Cl in the monolith), and Ca diffusive leaching (related
to change in matrix structure and loss of Ca).
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