UHPC – Development and Testing on Structural Elements

Vítek, Jan L.; Coufal, Robert; Čítek, David

doi:10.1016/j.proeng.2013.09.033

Cited by 35 publications

(22 citation statements)

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“…Based on current experience, this relatively new material with excellent mechanical and physical properties allows optimization of design rules of structural members and their details especially with regards to the anchorage length of the reinforcement [1]. Previous experiments that were been focused on the bond behavior between reinforcing bars and ordinary concrete and between prestressing strands and UHPC [2] confirmed the fact, that the excellent characteristics of UHPC material have very important effect on the bond properties. In the relation to this research, the article describes experimental verification of shear stress between prestressing strands and UHPC in extreme conditions.…”

Section: Introductionmentioning

confidence: 86%

Experimental Investigation on Material Properties of Ultra - High Performance Fiber Reinforced Concrete in Extreme Conditions

Čítek¹,

Fořt²,

Pavlík³

et al. 2017

Proceedings of the 3rd Annual International Conference on Advanced Material Engineering (AME 2017)

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Abstract. The Ultra -High Performance Fibre Reinforced Concrete (UHPFRC) is a very promising modern cementitious material suitable for application in special structures. The knowledge of performance of this relatively new material is limited. This paper deals in more detail with impact of extreme conditions (it means thermal loading) on bond properties between prestressing strands and UHPFRC and an influence of elevated temperature to final material properties of different UHPFRC mixtures. The first part of experimental work was focused on mechanical properties of UHPFRC and UHPC exposure to the high temperature (Tmax = 200°C -1000°C). Tested residual mechanical properties were compressive and flexural strengths, the fracture properties will be presented in this paper. Specimens in the first second experimental part were subjected to the cycling freeze-thaw testing. The relationship between bond behavior of both type of material (UHPC and ordinary concrete) and effect of cycling freeze-thaw tests was investigated. The obtained experimental data serve as a basis for further systematic experimental verification and more accurate information about the significantly higher material properties of UHP(FR)C and its behavior in extreme conditions. IntroductionExperimental research in the field of UHPC applications is very important. Based on current experience, this relatively new material with excellent mechanical and physical properties allows optimization of design rules of structural members and their details especially with regards to the anchorage length of the reinforcement [1]. Previous experiments that were been focused on the bond behavior between reinforcing bars and ordinary concrete and between prestressing strands and UHPC [2] confirmed the fact, that the excellent characteristics of UHPC material have very important effect on the bond properties. In the relation to this research, the article describes experimental verification of shear stress between prestressing strands and UHPC in extreme conditions. The effect of variable ambient temperature was investigated also on the specimens made from both type of material, UHPC and ordinary concrete C50/60. The specimens were exposed to cycling temperature in the range from -20°C to +20°C. The number of cycles varied from 100 to 400 cycles. Degradation of the material and related decline of material characteristics could have very significant impact on values of the bond stress.Exposition to elevated temperatures (Tmax = 200°C to Tmax = 1000°C) impact on degradation of material properties was content of second part of experimental program. High-temperature resistance is one of the particular importance of fire safety [9]. Adding steel fibers to UHPC matrix helps increase the values of compressive strength and mainly flexural strength. The effect of residual strength after high temperature exposure and comparison of steel fibers effect to final strength were main objectives of the second part of the article [4]. Specimens were exposed to temperatures 200-1000°C an...

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Section: Introductionmentioning

confidence: 86%

Experimental Investigation on Material Properties of Ultra - High Performance Fiber Reinforced Concrete in Extreme Conditions

Čítek¹,

Fořt²,

Pavlík³

et al. 2017

Proceedings of the 3rd Annual International Conference on Advanced Material Engineering (AME 2017)

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“…Current application of concretes of the highest grade in civil engineering is still relatively rare, with few successful applications as bridge decks, industrial floors, building facades (for example, Museum of Civilizations of Europe and the Mediterranean), wind turbine towers or prefabricated prestressed girders [4,6,7]. Other interesting applications of ultra-high performance concrete are lightweight shell structures (especially roof construction-for instance, the light rail roof platforms in Calgary) and permanent formwork (the advantage is the acceleration of the technological process of lightweight shell structures (especially roof construction-for instance, the light rail roof platforms in Calgary) and permanent formwork (the advantage is the acceleration of the technological process of building construction).…”

Section: Introductionmentioning

confidence: 99%

“…Upgrades are a brand new field for the application of UHPC. High strengths of ultra-high performance concrete are particularly advantageous for seismic upgrading of existing structures [6,9]. For the use of constructional components made of UHPC, especially prestressed girders, the resistance against high temperature is also of importance (natural or accidental fires).…”

Section: Introductionmentioning

confidence: 99%

Effect of Elevated Temperature on the Bond Strength of Prestressing Reinforcement in UHPC

et al. 2020

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The study explores the effect of elevated temperatures on the bond strength between prestressing reinforcement and ultra-high performance concrete (UHPC). Laboratory investigations reveal that the changes in bond strength correspond well with the changes in compressive strength of UHPC and their correlation can be mathematically described. Exposition of specimens to temperatures up to 200 °C does not reduce bond strength as a negative effect of increasing temperature is outweighed by the positive effect of thermal increase on the reactivity of silica fume in UHPC mixture. Above 200 °C, bond strength significantly reduces; for instance, a decrease by about 70% is observed at 800 °C. The decreases in compressive and bond strengths for temperatures above 400 °C are related to the changes of phase composition of UHPC matrix (as revealed by X-ray powder diffraction) and the changes in microstructure including the increase of porosity (verified by mercury intrusion porosimetry and observation of confocal microscopy) and development cracks detected by scanning electron microscopy. Future research should investigate the effect of relaxation of prestressing reinforcement with increasing temperature on bond strength reduction by numerical modelling.

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“…Ultra-high-performance concrete (UHPC) has been extensively investigated and is widely used in practical engineering, owing to its excellent mechanical properties, such as its high elastic modulus, high compressive and tensile strength, and strain hardening in tension. Many novel components and structures consisting of UHPC have been developed, such as the steel-UHPC composite deck system, delay-casted UHPC wet joint in bridge decks, and so on [1][2][3][4]. With the application of UHPC, the crack resistance and load-carrying capacity of these components are significantly improved.…”

Section: Introductionmentioning

confidence: 99%

Axial Behavior of Reinforced UHPC-NSC Composite Column under Compression

Hexiao

Gao

et al. 2020

Materials

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This paper proposes a novel reinforced ultra-high-performance concrete (UHPC)-normal strength concrete (NSC) composite column. The main feature of the reinforced UHPC-NSC composite column is the use of an exterior UHPC cover, which is helpful for improving the load-carrying capacity, deformability, and crack resistance. This study focused on the axial behavior of the reinforced UHPC-NSC composite column. A total of 12 specimens were designed to investigate the axial behavior of the composite column under compression. The thickness of the exterior UHPC cover, volumetric stirrup ratio, and construction method were considered as the main experimental parameters. The failure modes and strain–stress relationships are discussed in this paper. By introducing the exterior UHPC cover, the peak confined strength obviously improved. The compressive strain at the peak confined strength was mainly determined by the deformability of the plain UHPC material. The composite column resulted in a unique sudden drop immediately after the peak confined strength, owing to the rapid loss of the confining stress from the exterior UHPC cover. A trilinear model is proposed to describe the strain–stress relationship of the composite column. The results obtained by the modified model are in good agreement with the test results.

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UHPC – Development and Testing on Structural Elements

Cited by 35 publications

References 0 publications

Experimental Investigation on Material Properties of Ultra - High Performance Fiber Reinforced Concrete in Extreme Conditions

Experimental Investigation on Material Properties of Ultra - High Performance Fiber Reinforced Concrete in Extreme Conditions

Effect of Elevated Temperature on the Bond Strength of Prestressing Reinforcement in UHPC

Axial Behavior of Reinforced UHPC-NSC Composite Column under Compression

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