Autogenous Shrinkage in Plain Cement Mixtures

2008 ◽  
Vol 400-402 ◽  
pp. 137-143 ◽  
Author(s):  
Vinod Rajayogan ◽  
Obada Kayali
Keyword(s):  
Experimental Determination ◽  
High Performance ◽  
High Performance Concrete ◽  
Autogenous Shrinkage ◽  
Basic Mechanism ◽  
Realistic Model ◽  
Test Method ◽  
Ongoing Research ◽  
Cement Mixtures

Determination of a realistic model for the estimation of autogenous shrinkage in plain cement mixtures has been an ongoing research among researchers in high performance concrete. While no standard test method exists for the determination of autogenous shrinkage, various researchers have designed different test methods for measurement of autogenous shrinkage. Current study involved the experimental determination of autogenous shrinkage using the test method developed by O.M.Jensen and co-workers, complimented with non-contact eddy current sensors. Measurements were conducted from as early as 1.5 hours from the time of casting. The samples were placed in a constant temperature chamber and the temperature of the sample was also monitored using a thermocouple. The study was carried out on plain cement mixtures at three water cement ratios of 0.25, 0.32 and 0.38. Measurements were also conducted on simple sealed prismatic samples but these measurements could only be collected after 24 hours of casting. The work is supplemented with CEMHYD3D simulations of the samples at similar water-cement ratios under sealed conditions so as to understand the development of the microstructure of the cement responsible for autogenous shrinkage. While experimental determination of internal relative humidity is quite difficult, data regarding chemical shrinkage, amount of water left and the development of the discontinuous capillary network from the simulations help to understand the determined experimental values of autogenous shrinkage. A detailed explanation on the causes of autogenous shrinkage and the basic mechanism responsible for it has been presented.

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.

Bestimmung der Dauerhaftigkeit von Hochleistungsbeton mit Hilfe des CDF-Tests / Determination of the durability of high performance concrete by means of CDF-test

1999 ◽  
Vol 5 (1) ◽  
pp. 29-40
Author(s):  
R. Krumbach ◽  
U. Schmelter ◽  
K. Seyfarth
Keyword(s):  
Frost Resistance ◽  
High Strength Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Strength Concrete ◽  
Factors Influencing

Abstract Variable obsen>ations concerning frost resistance of high performance concrete have been made. The question arises which are the decisive factors influencing durability under the action of frost and de-icing salt. The proposed experiments are to be carried out in cooperation with F.A.- Finger - Institute of Bauhaus University Weimar. The aim of this study is to determine possible change of durability of high strength concrete, and to investigate the origin thereof. Measures to reduce the risk of reduced durability have to be found.

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.

Research Progress on Early Autogenous Shrinkage of Cement-Based Cementitious Materials

2013 ◽  
Vol 634-638 ◽  
pp. 2738-2741
Author(s):  
Wei Huang ◽  
Tao Zhang ◽  
Yun Yun Xu
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Research Work ◽  
Autogenous Shrinkage ◽  
Cementitious Materials ◽  
Mineral Admixtures ◽  
Research Progress ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Improvement Measures

Concrete autogenous shrinkage phenomenon would adversely affect the mechanical properties and durability of concrete, this phenomenon is important. Autogenous shrinkage problem of low water-cement ratio of the with high mineral admixtures, cement-based cementitious materials was introduced. The main reason for high-performance concrete early cracking being autogenous shrinkage was pointed out. Based on the home and abroad research status of low water cement ratio of the cement paste and concrete autogenous shrinkage, especially for early autogenous shrinkage phenomenon, the mechanism of autogenous shrinkage and the measure method is presented, and the improvement measures and the possible problems the need for further research work is presented.

The Determination of Frost Resistance on Ultra High Performance Concrete

2014 ◽  
Vol 1025-1026 ◽  
pp. 1005-1009 ◽  
Author(s):  
Michaela Kostelecká ◽  
Jiří Kolísko
Keyword(s):  
Frost Resistance ◽  
High Performance ◽  
High Performance Concrete ◽  
Silica Sand ◽  
Ultra High Performance Concrete ◽  
Concrete Technology ◽  
Normal Concrete ◽  
Different Types ◽  
High Range

The ultra high performance concrete (UHPC) has very special properties that are expressively different of normal concrete. Due to its high compression strength greater than 150 MPa, tensile strength greater than 20 MPa and improved durability, these represent significant advances in concrete technology. These materials include Portland cement, silica fume, quartz flour, fine silica sand, high-range water-reducer, water and either steel or organic fibres. Depending on the type of fibres used can influence the compressive strength. The article describes the tests of frost resistance on UHPC plates with different types of textiles armatures. The aim of the testing is describe influence of textiles armatures in UHPC matrix in extreme conditions.

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