CCEER-03-6: Creep and Shrinkage Losses in Highly Variable Climates
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Authors
Mortensen, Cole
Saiidi, Mehdi S.
Ladkany, Samaan
Issue Date
2003-09-01
Type
Report
Language
Keywords
CCEER
Alternative Title
Abstract
This study had several objectives, including studying the effects of aggregate type
and climate on creep and shrinltage losses, determining and quantifying tile effects of
moist-c~rring concrete (after prestressing), and proposing necessary revisions to the
current AASHTO equations for creep and shrinkage loss prediction. 111 Reno and Las
Vegas, twelve post-tensioiled concrete beams made with local aggregates were monitored
for creep and shrinkage losses along with a niunber of cylinder specilnens that were
monitored for creep and shrinkage strains independently. At each location, hvo box
girders were left indoors exposed to a more stable environment, and tvo box girders and
two solid beams were left outdoors exposed to precipitation and a wider varying
enviromlient. Of each pair of beams, one beam was kept moist for two weeks after
presu-essing (moist-curing) and one beam was not.
Tesring 2nd analysis found that moisn:re ca:: increase the stiffness of ap- ed
concrete by 20%, possibly reducing creep and shrinkage losses. Aggregate type was
fo~indto influence concrete susceptibility to creep and slxinlcage losses cmd the effects of
moisture. Testing and analysis also found that in some cases the liferime creep and
shrinkage losses calculated from measured extrapolated surface strains exceeded the
losses predicted by current prestress loss prediction metl-iods fi-on1 AASHTO: Naaman,
and Nawy. Based on these findings: necessary revisions to the AASHTO equations for
creep and sixinkage losses were proposed.
Description
Report No. CCEER-03-6
Citation
Publisher
License
In Copyright