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.

Application of Fiber Bragg Grating Sensor to Monitor Early Age Deformation of High Performance Concrete

2010 ◽  
Vol 450 ◽  
pp. 478-481 ◽  
Author(s):  
Ying Wei Yun ◽  
Xin Wu Wang ◽  
Ii Young Jang ◽  
Sung Soo Kim
Keyword(s):  
Fiber Bragg Grating ◽  
High Performance ◽  
High Performance Concrete ◽  
Bragg Grating ◽  
Early Age ◽  
Mass Concrete ◽  
Behavior Monitoring ◽  
Compensation Technique ◽  
Bragg Grating Sensor

This paper presents a method to monitor the early age properties of high performance concrete (HPC) specimens successfully by embedded fiber bragg grating (FBG) monitoring system. The results show that the deformation increases rapidly within the first 30 hours after HPC casting. And its value is up to 65 µε and 84µε for two specimens respectively. As for the durability and permeability of HPC, early age deformation of HPC is pretty high and can not be neglected. Meanwhile, temperature compensation technique for FBG strain sensor has been put forward, and it is applied to measure early age deformation and temperature of HPC beam in situ simultaneously. The monitoring technique used here can be extended to concrete early age behavior monitoring in mass concrete structure with any size.

Shrinkage Properties of Cement-Silica Fume Blended Pastes in Early Age

2017 ◽  
Vol 726 ◽  
pp. 521-526
Author(s):  
Di Zou ◽  
Lian Zhen Xiao ◽  
Wen Chong Shi
Keyword(s):  
Silica Fume ◽  
Rapid Growth ◽  
High Performance ◽  
High Performance Concrete ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Early Age ◽  
Shrinkage Ratio ◽  
Study Results ◽  
Expansion Period

The cement-silica fume blended pastes were prepared with different silica fume (SF) dosages of 0%, 5%, 10%, and 15% at different water-binder ratios (W/B) of 0.4 and 0.5. The autogenous shrinkage (AS) and the drying shrinkage (DS) of the paste samples in the hydration period of 7d (168 hours) were measured by a new measurement technique to explore the influence of W/B and silica fume incorporation on the shrinkage in early age. The study results can provide reference for high performance concrete mix design.It is found that ether the AS or the DS of the paste samples shows a similar pattern, and the AS development with hydration time appeared a temporary expansion period after a rapid growth, especially in the samples at a higher W/B or with a lower SF content. However, the DS development did not occur obvious expansion period.Three development trends were obtained for the factors of W/B and SF content. 1) the AS and DS of the pastes mainly occurred in early ages. The lower W/B, the shorter the rapid growth periods, and the higher the shrinkage ratio of 1d to 7d. For the pastes with W/B of 0.4, the AS grew rapidly in 1d and the DS grew rapidly in the first 10h, and the AS value in 1d reached to 63.6% of 7d, and the DS value reached to 62.1% of 7d in the paste with SF of 10%. For the pastes with W/B of 0.5, the rapid growth periods of the AS and DS respectively extended to 30~33h and 12h, and the AS value in 1d reached to 60.0% of 7d, and the DS value reached to 57.2% of 7d in the paste with SF of 10%. 2) The lower W/B, the higher the shrinkage ratio of the AS to the DS. When the SF dosage is 10%, the ratio of the AS value to the DS value of 7d is 21.66%~21.15% for W/B of 0.4, and only 6.06%~5.78% for the W/B of 0.5. 3) the higher SF content results in the higher AS in cement-SF blended pastes. For the pastes with W/B of 0.4, the ratio of the AS to the DS increased from 6.98% to 30.16% with the increase of content of SF from 5% to 15% in 1d, from 15.1% to 28.19% in 3d, from 16.78% to 26.16% in 7d.

Effect of the Expansion Agent on Early-Age Autogenous Shrinkage Stress of Concrete

2013 ◽  
Vol 838-841 ◽  
pp. 564-568
Author(s):  
Pan Xiu Wang
Keyword(s):  
Tensile Strength ◽  
Concrete Structure ◽  
High Performance ◽  
High Performance Concrete ◽  
Autogenous Shrinkage ◽  
Shrinkage Strain ◽  
Shrinkage Stress ◽  
Early Age ◽  
Concrete Cube

Early-age autogenous shrinkage is key problem of high performance concrete. It can cause a lot of early-age cracks in concrete structure and further endanger the permeability and durability. Adding expansion agent can control the early-age autogenous shrinkage strain and reduce the risk of early-age cracks. In this paper, the early-age autogenous shrinkage stress of concrete cube is calculated. The results show that, early-age autogenous shrinkage stress is larger than early-age tensile strength of concrete. So some cracks occur on the surface of concrete structure. By adding expansion agent, the early-age autogenous shrinkage strain and stress both decreases.

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