Modelling the early age behaviour of a low heat concrete bulkhead sealing an underground tunnel

2000 ◽  
Vol 27 (1) ◽  
pp. 112-125 ◽  
Author(s):  
Olivier Didry ◽  
Malcolm N Gray ◽  
André Cournut ◽  
James Graham
Keyword(s):  
Numerical Model ◽  
Temperature Rise ◽  
Numerical Models ◽  
Autogenous Shrinkage ◽  
Heat Of Hydration ◽  
High Mass ◽  
Maximum Temperature ◽  
Early Age ◽  
Mass Concrete ◽  
Government Organizations

A major experiment - the tunnel sealing experiment, related to the disposal of heat generating radioactive wastes in geological formations and supported by government organizations from Japan, France, U.S.A., and Canada, is being carried out at the Underground Research Laboratory of Atomic Energy of Canada Limited in Manitoba, Canada. Through a systematic process, the results from the experiment will be used to validate numerical models for the early age behaviour of high mass concrete bulkheads. A numerical model, based on the CESAR-LCPC finite element code equipped with the modules TEXO and MEXO, has been developed and used to predict the behaviour of a concrete bulkhead which will be built as part of the experiment. The TEXO-based component of the model which describes temperature changes has been validated. A maximum temperature rise in the concrete of 19°C is calculated. This will occur about 4 days after the concrete is cast. The temperature rise is low. This arises from the use of a specially developed low cement content concrete. Despite uncertainties in the MEXO-based model, which is used to describe the chemo-mechanical behaviour of the system, results indicate that it is unlikely that the concrete will crack, but a gap of 0.5 mm or more will develop between the bulkhead and the rock. Water leakage around the bulkhead through this gap could be significant and measures to seal this gap are advised. The modelling results recorded here will be tested against measurements made in the experiment. Thus, the numerical model will be formally validated and bounds to its use will be defined. Key words: concrete, bulkhead, sealing, early age behaviour, heat of hydration, autogenous shrinkage, underground repository, modelling.

scholarly journals Revisiting the Effect of Slag in Reducing Heat of Hydration in Concrete in Comparison to Other Supplementary Cementitious Materials

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1847 ◽  
Author(s):  
Hoon Moon ◽  
Sivakumar Ramanathan ◽  
Prannoy Suraneni ◽  
Chang-Seon Shon ◽  
Chang-Joon Lee ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Temperature Rise ◽  
Adiabatic Calorimetry ◽  
Blast Furnace Slag ◽  
Isothermal Calorimetry ◽  
Heat Of Hydration ◽  
Supplementary Cementitious Materials ◽  
Maximum Temperature ◽  
Mass Concrete ◽  
Furnace Slag

Blast furnace slag (SL) is an amorphous calcium aluminosilicate material that exhibits both pozzolanic and latent hydraulic activities. It has been successfully used to reduce the heat of hydration in mass concrete. However, SL currently available in the market generally experiences pre-treatment to increase its reactivity to be closer to that of portland cement. Therefore, using such pre-treated SL may not be applicable for reducing the heat of hydration in mass concrete. In this work, the adiabatic and semi-adiabatic temperature rise of concretes with 20% and 40% SL (mass replacement of cement) containing calcium sulfate were investigated. Isothermal calorimetry and thermal analysis (TGA) were used to study the hydration kinetics of cement paste at 23 and 50 °C. Results were compared with those with control cement and 20% replacements of silica fume, fly ash, and metakaolin. Results obtained from adiabatic calorimetry and isothermal calorimetry testing showed that the concrete with SL had somewhat higher maximum temperature rise and heat release compared to other materials, regardless of SL replacement levels. However, there was a delay in time to reach maximum temperature with increasing SL replacement level. At 50 °C, a significant acceleration was observed for SL, which is more likely related to the pozzolanic reaction than the hydraulic reaction. Semi-adiabatic calorimetry did not show a greater temperature rise for the SL compared to other materials; the differences in results between semi-adiabatic and adiabatic calorimetry are important and should be noted. Based on these results, it is concluded that the use of blast furnace slag should be carefully considered if used for mass concrete applications.

Properties of Autogenous Shrinkage in High-Strength Mass Concrete According to Hydration Heat Velocity

2011 ◽  
Vol 311-313 ◽  
pp. 1993-1999
Author(s):  
Kyung Mo Koo ◽  
Gyu Yong Kim ◽  
Hiroyuki Miyauchi ◽  
Yeon Woo Kang
Keyword(s):  
Autogenous Shrinkage ◽  
High Strength ◽  
Hydration Heat ◽  
Early Age ◽  
Mass Concrete ◽  
Close Relationship

The early-age properties and relationships between hydration heat and autogenous shrinkage in high-strength mass concrete are investigated through analysis of the history curves of hydration heat and autogenous shrinkage. To reduce the hydration heat velocity, micro encapsulated retarder (MR) that could retard cement reaction was applied. In the result of research, the hydration temperature and hydration heat velocity of high-strength mass concrete can be decreased with the reduction of size specimen and use of the retarder. A close relationship could be found between the hydration temperature and autogenous shrinkage; the higher the hydration heat velocity, the higher the autogenous shrinkage velocity and the greater the ultimate autogenous shrinkage.

Non-Structural Cracking Analysis of early Age of Reinforcement Concrete Wall

2012 ◽  
Vol 446-449 ◽  
pp. 251-259
Author(s):  
Ting Yao ◽  
Jian Ye Zhang ◽  
Jia Ping Liu ◽  
Qian Tian
Keyword(s):  
Structural Engineering ◽  
Maximum Temperature ◽  
Early Age ◽  
Mass Concrete ◽  
Concrete Wall ◽  
Crack Control ◽  
Leading Role ◽  
Real Behavior ◽  
Unique Source ◽  
Source Of Information

Structure monitoring has been increasingly valuable in recent years and has taken a leading role in the field of structural engineering. Date collected by early age monitoring represent a unique source of information for understanding the real behavior. In this paper, the temperatures evolution and concrete deformation evolution are obtained by real-time continuous monitoring of Reinforcement concrete(RC) wall. The result shows that the early age thermal cracking is one of the most important origin of several phenomena that imperil durability and shorten the lifespan of the structure. Though the wall is not considered as mass concrete, and has a big radiating surface, the maximum temperature can even reach up to 52°C due to heat generation of cement and the insulation of formwork, which can lead to shrinkage deformation when the temperature decreases. The measured experimental date can provide useful reference for early crack control and durability of RC concrete structure, and they can also be use to verify and improve the accuracy of the numerical results for RC wall, which is available in the future for basis to similar projects and research.

Influence of Casting Temperature on the Heat of Hydration in Mass Concrete Foundation with Ternary Cements

2014 ◽  
Vol 525 ◽  
pp. 478-481 ◽  
Author(s):  
Mi Hwa Lee ◽  
Young Seok Chae ◽  
Bae Su Khil ◽  
Hyun Do Yun
Keyword(s):  
Temperature Rise ◽  
Heat Of Hydration ◽  
Adiabatic Temperature ◽  
Casting Temperature ◽  
Mass Concrete ◽  
External Temperature ◽  
Maximum Heat ◽  
Adiabatic Temperature Rise ◽  
Concrete Foundation ◽  
Mat Foundation

This study is conducted to evaluate analytically the effect of casting temperature on the heat of hydration in mass concrete foundation with ternary cements and Type IV low heat cement. The mat foundation has the dimension of 15m length, 20m width and 3m depth. Casting temperatures considered for mat foundation consist of 10, 20 and 30C ̊. A commercial software MIDAS/Gen was used to analyze the hydration heat of mass concrete foundation. The maximum adiabatic temperature rise (K), and the coefficient of temperature rise˰˸α˹˰for thermal analysis were drawn from adiabatic temperature rise test. Analytical results show that blended cement PSLB_352 is the most effective to control the heat of hydration in mass concrete foundation and external temperature increases the maximum heat of hydration and crack probability of mat foundation with mass concrete.

Early Age Property Study of Phosphate Cement by Electrical Conductivity Measurement

2013 ◽  
Vol 544 ◽  
pp. 409-414
Author(s):  
Zhu Ding ◽  
Xiao Dong Wang ◽  
Bi Qin Dong ◽  
Zong Jin Li ◽  
Feng Xing
Keyword(s):  
Electrical Conductivity ◽  
Fly Ash ◽  
Temperature Rise ◽  
Conductivity Measurement ◽  
Maximum Temperature ◽  
Strength Development ◽  
Initial Reaction ◽  
Early Age ◽  
Electrical Conductivity Measurement ◽  
Hardening Process

The properties and electrical conductivity at early age of magnesium phosphate cement (MPC) was studied. Electrical resistivity or conductivity had been used for explaining the microstructure development of cement materials. In the current study, an electrodeless resistivity meter (ERM) was used to study the early property of MPC, which was mixed with and without fly ash respectively. The hardening process was investigated by the conductivity variation, incorporating with strength development and temperature rise during the initial reaction. The products and microstructure morphology of MPC paste were analysed by XRD and SEM. Results showed the mechanical property of MPC can be improved by fly ash. Fly ash lowers the maximum temperature rise during initial reaction of MPC with water. The electrical conductivity results divids the hardening process of MPC into three stages: acceleration, deceleration and stabilization. Conductivity measurement is an excellent method to explain the hardening process of MPC.

scholarly journals A Simplified Method for Real-Time Prediction of Temperature in Mass Concrete at Early Age

2020 ◽  
Vol 10 (13) ◽  
pp. 4451
Author(s):  
Guo An ◽  
Ning Yang ◽  
Qingbin Li ◽  
Yu Hu ◽  
Huiting Yang
Keyword(s):  
Cement Hydration ◽  
Cooling System ◽  
Concrete Block ◽  
Arch Dam ◽  
In Situ Monitoring ◽  
Cooling Effect ◽  
Maximum Temperature ◽  
Early Age ◽  
Mass Concrete ◽  
Measuring Point

According to the practice of temperature control in dam concrete, within a few days after a concrete block is poured, the temperature at the core of the concrete rises rapidly. The maximum temperature may still exceed the standard even under a relatively perfect post-cooling system, which is mostly caused by failure to quickly and correctly judge the development of the early-age temperature. This study investigates concrete temperature at an early age via in situ monitoring data collected from Baihetan arch dam and Wudongde arch dam. A simplified algorithm of temperature prediction is formed, which only considers the heat released by cement hydration and the cooling effect of cooling pipes. The influence of a cooling pipe on the measuring point of the thermometer is investigated, and a simple empirical formula to calculate the cooling effect is obtained. An equation for the rate of hydration temperature rise is achieved by combining measured data and the formula used to calculate the cooling effect. Furthermore, through the explorations of the related data, it is determined that the cement hydration ratio of the two dams is quite low during concreting. On the basis of the data collected from the field, the method to predict temperature proposed in this study is tested and proven.

Experimental Study on the Impact of Admixture for Concrete Heat of Hydration and Early-Age Contractile Properties

2012 ◽  
Vol 253-255 ◽  
pp. 385-389 ◽  
Author(s):  
Jian Cheng Sun ◽  
Bo Jun Wang ◽  
Wen Zhong Zhao
Keyword(s):  
Experimental Study ◽  
Fly Ash ◽  
Concrete Structure ◽  
Autogenous Shrinkage ◽  
Heat Of Hydration ◽  
Reducing Agent ◽  
Hydration Heat ◽  
Early Age ◽  
Mix Proportion ◽  
Structure Crack

During the technology development of modem concrete, concrete structure crack (especially early-age crack) becomes more and more serious and has been one of main research directions of civil engineering. This paper aims at the seriousness of concrete structure crack and presents one of main cause is that concrete early-age (especially autogenous shrinkage) become large through the experimental study. autogenous shrinkage are mainly belongs to temperature cracks and desiccation cracks. Analyses the affection of ash and water reducing agent on the hydration heat, under the optimum proportion experiment which aims at reducing he hydration heat of cement. The best program are obtained that double mix with 20% fly ash and 1.5% water reducing agent .Design mortar’s early anti-crack experiment, and study crack-resistance and other mechanical properties based on different ages & different mix proportion. From the experiment, analyses early cracking under the influence of admixtures. The mix proportion of 20% fly ash, 10% slag and 1.2% water reducing agent can minimize the creation of cracks.

scholarly journals Numerical and Experimental Evaluation and Heat Transfer Characteristics of a Soft Magnetic Transformer Built from Laminated Steel Plates

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7939
Author(s):  
Eduardo Cano-Pleite ◽  
Andrés Barrado ◽  
Néstor Garcia-Hernando ◽  
Emilio Olías ◽  
Antonio Soria-Verdugo
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Numerical Model ◽  
Numerical Models ◽  
Subsequent Development ◽  
Steel Plates ◽  
Maximum Temperature ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Anisotropic Thermal Conductivity

The present work evaluates, both experimentally and numerically, the heat transfer characteristics of a 5 kW three-phase transformer built from laminated steel sheets. The transformer is operated at different powers, and its temperature distribution is monitored using 108 thermocouples. The experimental measurements are used firstly to determine the heat dissipated at the core and the windings of the transformer. This information is used as an input for a finite element numerical model, which evaluates the heat transfer characteristics of the transformer. The model proposed in this work simply solves the diffusion equation inside the transformer, accounting for the anisotropic thermal conductivity of the different components of the transformer, together with well-known correlations at its boundaries. The results reveal that the proposed numerical model can correctly reproduce the maximum temperature, the temperature distribution, and the time-evolution of the temperature at specific points of the transformer measured during the experimental campaign. These results are of great use for the subsequent development of transformers of the same type in lab-scale or industrial-scale size and reveal the applicability of simplified numerical models to accurately predict the heat transfer characteristics of this kind of transformers.

scholarly journals Application of hydration heat inhibitor in crack control of mass concrete of tunnel side wall

2021 ◽  
Vol 283 ◽  
pp. 01032
Author(s):  
XiZhi Wang ◽  
MinSheng Shi ◽  
XinGang Wang
Keyword(s):  
Temperature Rise ◽  
Concrete Strength ◽  
Side Wall ◽  
Hydration Heat ◽  
Structural Deformation ◽  
Maximum Temperature ◽  
Optimal Dosage ◽  
Mass Concrete ◽  
Control Effect ◽  
Crack Control

The structural deformation caused by temperature change is the main reason for cracking of mass concrete. In order to avoid or reduce the crack of the side wall of cast-in-place mass concrete in tunnel, the effects of different dosage of hydration heat inhibitor on the internal temperature rise curve of concrete, strength and the properties of the mixture are analyzed through experimental research, and the optimal dosage of 1% of cementing material is finally determined. The engineering application results show that after adding hydration heat inhibitor to the tunnel side wall concrete, the maximum temperature rise in the tunnel side wall is obviously reduced, and the arrival time of the temperature peak is delayed. No cracks appear in the tunnel side wall, and the crack control effect is good.

Thermal Characteristics of Mat Foundation with Different Lift Thickness of Mass Concrete Including Strontium-Based Latent Heat Binder

2014 ◽  
Vol 525 ◽  
pp. 461-464
Author(s):  
Kyung Lim Ahn ◽  
Qi Bo Liang ◽  
Bae Su Khil ◽  
Hyun Do Yun
Keyword(s):  
Latent Heat ◽  
Temperature Rise ◽  
Volume Fraction ◽  
Heat Of Hydration ◽  
Adiabatic Temperature ◽  
Hydration Heat ◽  
Mass Concrete ◽  
Adiabatic Temperature Rise ◽  
Concrete Foundation ◽  
Mat Foundation

This study provides analytical results for heat of hydration in the mat foundation with mass concretes to investigate the effect of lift thickness in the mat foundation on the hydration heat and crack characteristics of mat foundation with mass concrete. Mass concretes were mixed with ternary cement with 1% strontium-based latent heat binder at volume fraction and Type IV low heat cement. The mat foundation has the dimension of 15m length, 20m width and 3m depth. Lift thickness of mass concrete for mat foundation was varied from 1.0m to 3.0m. A commercial software MIDAS/Gen was used to analyze the hydration heat of mass concrete foundation. The maximum adiabatic temperature rise (K), and the coefficient of temperature rise (α) for thermal analysis were drawn from adiabatic temperature rise test. Based on the results of the finite element analysis for mat foundation with different lift thickness, the highest internal temperature and thermal stress increased with increasing with lift thickness of foundation. However, for foundation constructed with premixed strontium based latent heat binder (PSLB) concrete, this phenomenon was less remarkable compared to mass concrete foundation made with low heat cement.

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