Residual Compressive Strength Prediction Model for Concrete Subject to High Temperatures Using Ultrasonic Pulse Velocity

Kim, Wonchang; Choi, Hyeonggil; Lee, Tae-Gyu

doi:10.3390/ma16020515

Cited by 8 publications

(8 citation statements)

References 36 publications

(45 reference statements)

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“…As demonstrated in the literature, the compressive strength was significantly decreased when the temperature of concrete was over 500 °C [37,38], at which the heated concrete was removed before concrete structures were strengthened. Hence, five exposure temperatures, including ambient, 100 °C, 200 °C, 300 °C, and 400 °C, were adopted and labeled as TA, T1, T2, T3, and T4, respectively.…”

Section: Details Of Test Specimensmentioning

confidence: 80%

Bonded Behavior of Hybrid-Bonded CFRP to Heat-Damaged Concrete Interface

Liu,

Wang,

et al. 2023

Buildings

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The reliable bond of CFRP to heat-damaged concrete is fundamental to ensuring cooperative working when the CFRP is applied for strengthening fire-damaged concrete structures. In this paper, the bond performance of hybrid-bonded (HB) CFRP to a heat-damaged concrete surface was investigated by using single shear tests. The concrete blocks were initially heat-damaged to temperatures of 100 °C, 200 °C, 300 °C, and 400 °C. The heat-damaged blocks were subsequently bonded with CFRP using the HB technique. The primary experiment parameters were the exposure temperature, the number of mechanical fasteners, and the bonded layers of CFRP. The test results show that the external-bonded (EB) and HB-CFRP joints with concrete exposed to a temperature of 400 °C were prone to fail with concrete shear-tension due to the decreased shear strength of concrete at high temperatures. The EB- and HB-CFRP joints with heat-damaged concrete anchored with no more than three fasteners present a higher bond than the reference joints with unheated concrete, while the HB-CFRP joints anchored with three fasteners provide a decreased bond capacity with the increase in exposure temperature. The utilization rate of single-layer CFRP joints with unheated concrete increased by 57.9%, 139.5%, and 136.8% with the mechanical fasteners in numbers of one, two, and three compared with the reference specimen. Accordingly, the bond capacity increased by 111.8%, 128.4%, and 186.7%. Finally, a model was proposed to estimate the bond strength of HB-CFRP joints with heat-damaged concrete.

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Section: Details Of Test Specimensmentioning

confidence: 80%

Bonded Behavior of Hybrid-Bonded CFRP to Heat-Damaged Concrete Interface

Liu,

Wang,

et al. 2023

Buildings

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“…The general form of the conduction differential equation in the unsteady state [18] in the Cartesian coordinate system can be expressed as Equation (1). From left to right in Equation (1), the first subitem is the increment of the thermodynamic energy of the microelement per unit time (the unsteady term).…”

Section: The Conduction Differential Equation In the Unsteady Statementioning

confidence: 99%

“…Engineering diseases triggered via elevated temperatures have gradually become increasingly outstanding. As an example, six tunnels in the Lari railway are subjected to heat damage begotten via elevated ground temperatures, with the temperature of rock and water up to 80 • C. High ground temperatures can worsen the construction environment and affect the mechanical properties [1] and durability of concrete. Methods to solve this problem include developing and applying high-performance materials [2], setting up insulation layers [3], adopting air layer structures [4], and strengthening ventilation and cooling in tunnels [5].…”

Section: Introductionmentioning

confidence: 99%

A Theoretical Study on the Spatiotemporal Variation in the Temperature Field in Linings of High-Water-Temperature Tunnels

Huang,

et al. 2023

Materials

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On the basis of the theory of unsteady heat conduction, discrete equations for the unsteady temperature field in the secondary linings of high-water-temperature tunnels when considering the hydration heat of lining concrete were derived and established. Spatiotemporal variation in the temperature field of tunnel linings was revealed through the analysis of numerical examples. Research demonstrates that the temperature of the secondary lining within a thickness range of approximately 15 cm near the tunnel clearance decreases sharply under the condition that the lining thickness is 35 cm. The higher the temperature on the lining’s outer surface, the more drastically the lining temperature decreases. When considering the hydration heat of lining concrete, the lining temperature increases to a certain extent after a sudden drop, reaching stability after approximately 20 h, and the lining temperature is approximately 1–2 °C higher than that without taking concrete hydration heat into account. The temperature difference between the tunnel lining’s core and its inner and outer surfaces is positively and negatively correlated with the temperature of the secondary lining’s outer surface, respectively. When the temperature of the secondary lining’s outer surface is not higher than 65 °C, the temperature difference between the tunnel lining’s core and its inner and outer surfaces is less than 20 °C. Conversely, it partially or completely exceeds 20 °C, in which case an insulation method is recommended to utilize to prevent thermal cracks in secondary linings triggered via a high temperature difference.

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“…Results of correlation analysis shows a difference of approximately 10.0% between the NC and the HT specimens. (9,10) .…”

Section: Introductionmentioning

confidence: 99%

Review of Ultrasonic Pulse Methods for Evaluation of Mechanical Properties of Concrete with Different Percentages of Non-sintered Hwangto at High Temperature

Kim¹,

Kim²,

Jeong³

et al. 2023

Fire Sci. Eng.

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In this study, the effect of non-sintered hwangto on the high-temperature residual mechanical properties of concrete is analyzed. The specimens are classified as NC and HT, which are mixed with 15% and 30% non-sintered hwangto, respectively, and the W/B is set 0.33. The unit weight, compressive strength, and ultrasonic pulse velocity of the specimens heated at room temperature and at 100 °C, 200 °C, 300 °C, 500 °C, and 700 °C are analyzed, and the correlation between ultrasonic pulse velocity and residual compressive strength is analyzed. The analysis result shows that the higher the mixing ratio of non-sintered hwangto, the lower is the mass loss rate at high temperature and the higher is the residual compressive strength of HT compared with those of NC. Meanwhile, the ultrasonic pulse velocity of HT is similar to or slightly higher than those of NC in areas with high temperatures of 300 °C or beyond. Results of correlation analysis shows a difference of approximately 10.0% between the NC and the HT specimens.

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Residual Compressive Strength Prediction Model for Concrete Subject to High Temperatures Using Ultrasonic Pulse Velocity

Cited by 8 publications

References 36 publications

Bonded Behavior of Hybrid-Bonded CFRP to Heat-Damaged Concrete Interface

Bonded Behavior of Hybrid-Bonded CFRP to Heat-Damaged Concrete Interface

A Theoretical Study on the Spatiotemporal Variation in the Temperature Field in Linings of High-Water-Temperature Tunnels

Review of Ultrasonic Pulse Methods for Evaluation of Mechanical Properties of Concrete with Different Percentages of Non-sintered Hwangto at High Temperature

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