Effect of drying conditions on autogenous shrinkage in ultra-high performance concrete at early-age

2010 ◽  
Vol 44 (5) ◽  
pp. 879-899 ◽  
Author(s):  
A. M. Soliman ◽  
M. L. Nehdi
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Autogenous Shrinkage ◽  
Early Age ◽  
Ultra High Performance Concrete ◽  
Drying Conditions

The Influence of Chemical Admixtures on the Autogenous Shrinkage Ultra-High Performance Concrete

2010 ◽  
Vol 452-453 ◽  
pp. 725-728 ◽  
Author(s):  
Jung Jun Park ◽  
Sung Wook Kim ◽  
Gum Sung Ryu ◽  
Kwang Myung Lee
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Autogenous Shrinkage ◽  
Pulse Velocity ◽  
Reducing Agent ◽  
Shrinkage Stress ◽  
Early Age ◽  
Ultra High Performance Concrete ◽  
Expansive Additive ◽  
Shrinkage Reducing Agent

Ultra-high performance concrete (UHPC) is a material developing remarkable performance with compressive strength of about 200 MPa and flexural strength of approximately 30 MPa on which research is actively conducted today. However, UHPC is also characterized by a mixing composed of a high specific quantity of binder that is a W/B ratio of about 0.2, which requires to examine the effects of the autogenous shrinkage. Accordingly, this study investigates the effects of the use of expansive additive and water reducing agent on the autogenous shrinkage of UHPC at early age. To that goal, autogenous shrinkage test and ultrasonic pulse velocity (UPV) monitoring are conducted for a mixing of UHPC using expansive additive and shrinkage reducing agent. The experimental results reveal that the autogenous shrinkage of UHPC reduces by 24% for a mix of UHPC adopting both 7.5% of expansive additive and 1% of shrinkage reducing agent compared to the mix without admixture. Furthermore, this mix is seen to compensate the autogenous shrinkage occurring at early age when UHPC develops its largest stiffness in view of the UPV evolution curve. At that time, the shrinkage stress seems to be extremely softened.

Early-Age Autogenous Shrinkage of High-Performance Concrete Columns by Embedded Fiber Bragg-Grating Sensor

2009 ◽  
Vol 419-420 ◽  
pp. 1-4 ◽  
Author(s):  
Ying Wei Yun ◽  
Ii Young Jang ◽  
Seong Kyum Kim ◽  
Seung Min Park
Keyword(s):  
Fiber Bragg Grating ◽  
High Performance ◽  
High Performance Concrete ◽  
Construction Material ◽  
Autogenous Shrinkage ◽  
Strain Sensor ◽  
Bragg Grating ◽  
Early Age ◽  
Long Time ◽  
Sensor Temperature

High-performance concrete (HPC) as a promising construction material has been widely used in infrastructures and high-rise buildings etc. However, its pretty high autogenous shrinkage (AS) especially in its early age becomes one of the key problems endangering long-time durability of HPC structures. This paper carried out the early age AS research of large scaled HPC column specimens by embedded Fiber Bragg-Grating (FBG) strain sensor. Temperature compensation for FBG strain sensor by thermocouple was also attempted in this paper, and the results were reasonable and acceptable comparing with the result compensated by FBG temperature sensor. Reinforcement influence, size effect and temperature effect on HPC AS were also analyzed respectively in this paper.

scholarly journals Shrinkage in Ultra-High Performance Concrete Overlays on Concrete Bridge Decks

2019 ◽  
Vol 271 ◽  
pp. 07008
Author(s):  
William Toledo ◽  
Leticia Davila ◽  
Ahmed Al-Basha ◽  
Craig Newtson ◽  
Brad Weldon
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Bridge Decks ◽  
Plastic State ◽  
Early Age ◽  
Concrete Bridge ◽  
Ultra High Performance Concrete ◽  
Concrete Overlays ◽  
Concrete Bridge Decks ◽  
Normal Strength

This paper investigates the shrinkage and thermal effects of an ultra-high performance concrete (UHPC) mixture proposed for use as an overlay material for concrete bridge decks. In this study, early-age and longer-term shrinkage tests were performed on the locally produced UHPC. Thermal and shrinkage effects in normal strength concrete slabs overlaid with UHPC were also observed. Early-age shrinkage testing showed that approximately 55% of the strain occurred in the plastic state and may not contribute to bond stresses since the elastic modulus of the UHPC should be small at such early ages. Thickness of the substrate and amount of reinforcing steel were important factors for shrinkage in the slabs. The thickest slab experienced greater shrinkage than thinner slabs. Comparing this slab to a thinner slab with the same reinforcement indicated that reinforcement ratio is more important than the area of steel.

Evaluation of Setting Time in Ultra High Performance Concrete

2012 ◽  
Vol 525-526 ◽  
pp. 621-624
Author(s):  
Sung Wook Kim ◽  
Jung Jun Park ◽  
Doo Youl Yoo ◽  
Young Soo Yoon
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Setting Time ◽  
Autogenous Shrinkage ◽  
High Strength ◽  
Initial Crack ◽  
Test Method ◽  
Plastic State ◽  
Ultra High Performance Concrete ◽  
Confining Stress

Ultra high performance concrete (UHPC), characterized by a high strength and high ductility, is also subjected to large shrinkage due to its low water-to-binder ratio and its large content in high fineness materials. The large amount of autogenous shrinkage of UHPC can induce crack on structural member when it was restrained with reinforcement and form. However, shrinkage of UHPC in plastic state is not generating confining stress, which is the main cause of initial crack. Normally, the setting time in concrete is an index to distinguish shrinkage which occur confining stress or not. An estimation of setting time is conducted in compliance with ASTM C 403 till now however, that test standard reveals error of results due to discordance of test condition as following with concrete type. This study therefore evaluated setting time of UHPC through the modified test method which was proposed by KICT. Test results and analyses proved a discrepancy of setting time between ASTM and proposed method. The proposed method put faith in evaluation of setting time in accordance with UHPC.

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