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.

scholarly journals Modeling temperature profile in mass concrete at early ages of cement hydration

2021 ◽  
Vol 10 (1) ◽  
pp. 64
Author(s):  
Ugwuanyi Donald Chidiebere ◽  
Okafor Fidelis Onyebuchi
Keyword(s):  
Ambient Temperature ◽  
Temperature Profile ◽  
Cement Hydration ◽  
Concrete Block ◽  
Control Measures ◽  
Mass Concrete ◽  
Thermally Induced ◽  
Thermal Cracks ◽  
Concrete Placement ◽  
And Control

Thermally induced cracks due to temperature gradient in mass concrete have adverse effects on its durability and service life. Heat released during the hydration of Portland cement in early age mass concrete can be quite excessive depending on the ambient temperature, cement content of the concrete mix and the size. Finite difference model using Crank Nicholson implicit method was developed based on the two dimensional unsteady state heat conduction. Optimized MATLAB based software was developed for simulation and data visualization. A mass concrete block cast with standard mix ratio and water cement ratio was used to verify the efficacy of the model. Type-K thermocouple and digital thermometer were used to monitor the temperature at time intervals. The temperature profile showed a hotter core and cooler surface except for the initial placement temperature, which exhibited a uniform temperature for all thermocouple locations. Peak temperature values were recorded within the first day of concrete placement. The model successfully predicted the temperature profile of the mass concrete at early ages of cement hydration. With the knowledge of the ambient temperature and the configuration of the mass concrete, the model can reliably predict the temperature profile from which potential for thermal cracks occurrence can be determined to enable suitable proactive preventive and control measures.  

Study on the Drafting and Early-Warning of Temperature Double-Control Index of Different Sections & Periods of Concrete Block

2012 ◽  
Vol 188 ◽  
pp. 253-258
Author(s):  
Dong Sheng Shen ◽  
Yao Ying Huang ◽  
Yi Hong Zhou ◽  
Dan Dan Liu ◽  
Xiang Ze Gao
Keyword(s):  
Prediction Model ◽  
Probabilistic Method ◽  
Concrete Block ◽  
Arch Dam ◽  
Maximum Temperature ◽  
Measured Temperature ◽  
Dynamic Feedback ◽  
High Arch Dam ◽  
Concrete Blocks ◽  
Real Time Tracking

Although real-time tracking and feedback were carried out for the dam concrete construction process, there was still certain blindness in the construction units. The temperature double-control index, which is the allowable temperature and temperature gradient under typical age before concrete block reaching its maximum temperature, was proposed in this paper on the basis of the analysis of measured temperature process curves of concrete blocks. The probabilistic method was applied to draft the temperature double-control index of different sections and periods based on the measured temperature process curve of the poured block of a constructing extra-high arch dam in southwest China. Furthermore, the prediction model was also provided and applied in the dynamic feedback of new pouring block. It is demonstrated by the practice that the prediction model proposed in this paper has better pertinence and maneuverability for the construction units to control the maximum temperature of concrete block, i.e. the maximum temperature in high temperature season and in low temperature season are both controllable.

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.

scholarly journals The use of ice to cool the concrete mix in the construction of massive structures

2021 ◽  
Vol 264 ◽  
pp. 02047
Author(s):  
Nikolay Aniskin ◽  
Trong Chuc Nguyen ◽  
Anh Kiet Bui
Keyword(s):  
Heat Transfer ◽  
Energy Balance ◽  
Initial Temperature ◽  
Concrete Block ◽  
Heat Transfer Process ◽  
The Other ◽  
Maximum Temperature ◽  
Mass Concrete ◽  
Concrete Mix ◽  
Practical Design

This article proposes a formula to determine the required amount of ice to partially replace the water in the concrete mix to control the initial temperature of the concrete mix and reduce possible cracking. The formula was created based on the principle of energy balance in the heat transfer process. At the same time, the obtained results were compared with the other methods. Besides, an example of the calculation for a concrete block during the construction was performed. The maximum temperature and temperature difference in mass concrete obtained depend significantly on the initial temperature of the concrete mixture. The research results and the proposed techniques can be used in the practical design of mass concrete structures.

scholarly journals Analytical model for prediction of temperature distribution in early age mass concrete

2020 ◽  
Vol 9 (2) ◽  
pp. 359
Author(s):  
Ugwuanyi Donald Chidiebere ◽  
Okafor Fidelis Onyebuchi
Keyword(s):  
Temperature Distribution ◽  
Analytical Model ◽  
Separation Of Variables ◽  
Concrete Structures ◽  
Concrete Block ◽  
Early Age ◽  
Mass Concrete ◽  
Thermally Induced ◽  
Thermal Cracks ◽  
Concrete Placement

Thermally induced cracks have far-reaching implications on the durability of concrete structures. When cement mixes with water, the reaction is exothermic implying the release of heat. In the case of mass concrete structures, quite a substantial increase in internal temperature may be experienced depending on the ambient temperature and cement content in the mix. The objective of the paper is to develop a mathematical model to predict the time dependent temperature profile in early age mass concrete. Mass concrete block was used to verify the model. Type-K thermocouples placed at various positions and digital thermometer was used to monitor the temperature distribution within the mass concrete block at intervals. The highest temperature values occurred within the core of the mass concrete after one day of concrete placement. Analytical model was developed by applying method of separation of variables and orthogonality relation to two dimensional unsteady state heat conduction equations. The model equation was evaluated and using MATLAB based computer programe. The model successfully predicted the temperature variation within the mass concrete with time. It is therefore suitable for use in the assessment of thermal cracks potential in mass concrete structures. 

scholarly journals Building a nomogram to predict maximum temperature in mass concrete at an early age

2021 ◽  
Vol 263 ◽  
pp. 01008
Author(s):  
Trong - Chuc Nguyen ◽  
Van - Quang Nguyen ◽  
Nikolay Aniskin ◽  
Ba - Thang Phung ◽  
Quoc - Long Hoang
Keyword(s):  
Initial Temperature ◽  
Concrete Structures ◽  
Temperature History ◽  
Maximum Temperature ◽  
Early Age ◽  
Mass Concrete ◽  
The Finite Element Method ◽  
Thermal Cracks ◽  
Massive Concrete ◽  
Main Factor

During the construction of massive concrete structures, the main factor that affects the structure is temperature. The resulting temperature is the result of hydration of the cement and some other factors, which leads to the formation of thermal cracks at an early age. So, the prediction of temperature history in massive concrete structures has been a very important problem. In this study, with the help of numerical methods, a temperature nomogram was built to quickly determine the maximum temperature in concrete structures with different parameters such as size, cement content, and the initial temperature of the concrete mixture. The obtained temperature nomogram has been compared with the results of the finite element method and the model experiment gives reliable results. It can be used to predict maximum temperature in mass concrete structures to prevent the formation of thermal cracks.

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.

Spray Cooling for Time Resolved Emission Measurements of ICs

2004 ◽  
Author(s):  
Rama R. Goruganthu ◽  
David Bethke ◽  
Shawn McBride ◽  
Tom Crawford ◽  
Jonathan Frank ◽  
...  
Keyword(s):  
Heat Flux ◽  
Thermal Performance ◽  
Flip Chip ◽  
Cooling System ◽  
Spray Cooling ◽  
Junction Temperature ◽  
Maximum Temperature ◽  
Uniform Heat Flux ◽  
High Heat Flux ◽  
Time Resolved

Abstract Spray cooling is implemented on an engineering tool for Time Resolved Emission measurements using a silicon solid immersion lens to achieve high spatial resolution and for probing high heat flux devices. Thermal performance is characterized using a thermal test vehicle consisting of a 4x3 array of cells each with a heater element and a thermal diode to monitor the temperature within the cell. The flip-chip packaged TTV is operated to achieve uniform heat flux across the die. The temperature distribution across the die is measured on the 4x3 grid of the die for various heat loads up to 180 W with corresponding heat flux of 204 W/cm2. Using water as coolant the maximum temperature differential across the die was about 30 °C while keeping the maximum junction temperature below 95 °C and at a heat flux of 200 W/cm2. Details of the thermal performance of spray cooling system as a function of flow rate, coolant

Impact of limestone fineness on cement hydration at early age

2021 ◽  
Vol 147 ◽  
pp. 106515
Author(s):  
Yosra Briki ◽  
Maciej Zajac ◽  
Mohsen Ben Haha ◽  
Karen Scrivener
Keyword(s):  
Cement Hydration ◽  
Early Age

Establishing and Satisfying Thermal Requirements for Drilled Shaft Concrete Based on Durability Considerations

2021 ◽  
pp. 036119812199635
Author(s):  
Andrew Z. Boeckmann ◽  
Zakaria El-tayash ◽  
J. Erik Loehr
Keyword(s):  
Mechanical Response ◽  
Large Diameter ◽  
Thermal Cracking ◽  
Drilled Shafts ◽  
Maximum Temperature ◽  
Design Parameters ◽  
Mass Concrete ◽  
Temperature Differential ◽  
Thermal Requirements ◽  
Ettringite Formation

Some U.S. transportation agencies have recently applied mass concrete provisions to drilled shafts, imposing limits on maximum temperatures and maximum temperature differentials. On one hand, temperatures commonly observed in large-diameter drilled shafts have been observed to cause delayed ettringite formation (DEF) and thermal cracking in above-ground concrete elements. On the other, the reinforcement and confinement unique to drilled shafts should provide resistance to thermal cracking, and the provisions that have been applied are based on dated practices for above-ground concrete. This paper establishes a rational procedure for design of drilled shafts for durability requirements in response to hydration temperatures, which addresses both DEF and thermal cracking. DEF is addressed through maximum temperature differential limitations that are based on concrete mix design parameters. Thermal cracking is addressed through calculations that explicitly consider the thermo-mechanical response of concrete for predicted temperatures. Results from application of the procedure indicate consideration of DEF and thermal cracking potential for drilled shafts is prudent, but provisions that have been applied to date are overly restrictive in many circumstances, particularly the commonly adopted 35°F maximum temperature differential provision.

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