Summary: | 碩士 === 國立中興大學 === 土木工程學系所 === 104 === A majority of the freeways and expressways were built to have many elevated sections in Taiwan. Most of the viaducts are designed as long-span or continuous ones, which means that the use of numerous expansion joints is imperative. These joints in each sections have been used for many years and recently they were repaired or renewed. The repairs were done through using very-early-high-strength concrete to minimize the impact to the traffic. This is because very-early-high–strength concrete can reach the required strength for restoring traffic in a short amount of time.
The objective of this thesis is to establish the relationship between ultrasound pulse velocity (UPV) and compression strength of the very- early-high-strength concrete. In consideration of the fact that only one accessible surface is available in field, we suggest to use the impact-echo test to measure the speed of P-wave (IEPV) propagating along surface. Then we concert IEPV into UPV with a coefficient accounting for the difference between IEPV and UPV, which was determined in laboratory. Subsequently, using the established relationship curve between UPV and strength, we can estimate the strength of concrete with the measured IEPV.
The experimental results show that the error of estimated strength is within 10%. This shows that the established relationship curve is highly suitable for application. In impact-echo tests, the wave speed measured by using two receivers having a distance of 20 centimeters is nearly identical to that measured with 30 centimeters. Thus, these results show that an in-place impact-echo test may use two receivers with a distance of 20 centimeters.
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