| Summary: | 碩士 === 國立中興大學 === 土木工程學系 === 85 === The objective of this thesis was to determine the feasibility
of using nondestructive testing (NDT) techniques for on-
site evaluation of high-performance concrete (HPC)
quality. An 85-story high-rise building whose steel box
columns are filled with HPC is under construction in
Kao-Hsiung, Taiwan. In this case, it is very difficult to
evaluate the HPC quality by means of visible inspection
or conventional techniques. It has been reported that HPC
has significant autogeneous shrinkage which would lead
to cracks inside the concrete of at the interface
between the concrete and steel box column due to the forces
introduced by the interface friction and shear studs. It
is very challenging and practically important to develop
effective NDT techniques for detection of such cracks. In
addition, it is widely recognized that development of
nondestructive techniques for measuring the in-place strength of
concrete in structures is important. For normal strength
concrete (NSC), various mixture proportions produce a
scattering strength-velocity relationship. This poor
correlation is mainly due to the fact that the compressive
strength of normal strength concrete is controlled by the
strength of mortar but the pulse velocity is influenced
significantly by the quality and amount of coarse
aggregate. For HPC, the strength of the hydrated cement
paste is very high and sometimes higher than the strength of the
aggregate particles. The bond between aggregate and hydrated
cement paste is strong enough to transfer significantly
stress across the paste-aggregate interface.As a result,
strength as well as pulse velocity of HPC are closely related
to the quality and amount of coarse aggregate. It is believed
that the strength-velocity relationship for high performance
concrete can be much better than that for normal strength
concrete. Results obtained from the studies show that the
use of pulse velocity to estimate compressive strength of
HPC is feasible mainly because the pulse velocity is not so
sensitive to the change in aggregate content.
|
|---|
