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.

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. 

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.

Fly-Ash Concretes of 50% of the Replacement Ratio to Reduce the Cracking in Concrete Structures

2013 ◽  
Vol 405-408 ◽  
pp. 2665-2670 ◽  
Author(s):  
Ming Jie Mao ◽  
Qiu Ning Yang ◽  
Wen Bo Zhang ◽  
Isamu Yoshitake
Keyword(s):  
Fly Ash ◽  
Concrete Structures ◽  
High Volume ◽  
Pozzolanic Reaction ◽  
Strength Development ◽  
Early Age ◽  
Replacement Ratio ◽  
Fly Ash Concrete ◽  
Massive Concrete ◽  
Normal Strength

Fly-ash concrete used in massive concrete structure has superior advantages to reduce hydration heat. On the other hand, the fly-ash concrete has negative property of low strength development at early age because pozzolanic reaction of fly-ash activates at mature age, such as after 28 days. To investigate these characteristics of fly-ash used in concrete, the present study discusses thermal cracking possibility of fly-ash concrete by using FE analysis software. The present study employs prediction formulae proposed by Zhang and Japanese design code in the simulations. The objects in this study are normal strength concrete mixed of fly-ash up to 50% of replacement ratio to cement. The comparative investigations show that temperature effect is more significant than strength development at early age. Based on the analytical study, high volume fly-ash concretes of 30-50% of the replacement ratio can be concluded as effective and useful materials to reduce the cracking possibility in massive concrete structures. Keywords-Fly-ash concrete; Early Age, Prediction Formulae for Strength; Thermal Stress Analysis

scholarly journals XFEM for Thermal Crack of Massive Concrete

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Guowei Liu ◽  
Yu Hu ◽  
Qingbin Li ◽  
Zheng Zuo
Keyword(s):  
Cooling System ◽  
Concrete Structures ◽  
Thermal Cracking ◽  
Pipe System ◽  
Degree Of Hydration ◽  
Thermal Cracks ◽  
Massive Concrete ◽  
Cooling Pipe ◽  
Equivalent Equation ◽  
Viscoelastic Constitutive Model

Thermal cracking of massive concrete structures occurs as a result of stresses caused by hydration in real environment conditions. The extended finite element method that combines thermal fields and creep is used in this study to analyze the thermal cracking of massive concrete structures. The temperature field is accurately simulated through an equivalent equation of heat conduction that considers the effect of a cooling pipe system. The time-dependent creep behavior of massive concrete is determined by the viscoelastic constitutive model with Prony series. Based on the degree of hydration, we consider the main properties related to cracking evolving with time. Numerical simulations of a real massive concrete structure are conducted. Results show that the developed method is efficient for numerical calculations of thermal cracks on massive concrete. Further analyses indicate that a cooling system and appropriate heat preservation measures can efficiently prevent the occurrence of thermal cracks.

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 Mitigation of early-age cracking in concrete structures

2019 ◽  
Vol 284 ◽  
pp. 07005 ◽  
Author(s):  
Anton Schindler ◽  
Benjamin Byard ◽  
Aravind Tankasala
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Cementitious Materials ◽  
Temperature History ◽  
Early Age ◽  
Concrete Bridge ◽  
Mass Concrete ◽  
Concrete Bridge Decks ◽  
History Of ◽  
Concrete Elements

Early-age cracking can adversely affect the behavior and durability of concrete elements. This paper will cover means to mitigate early-age cracking in concrete bridge decks and mass concrete elements. The development of in-place stresses is affected by the shrinkage, coefficient of thermal expansion, setting characteristics, restraint conditions, stress relaxation, and temperature history of the hardening concrete. The tensile strength is impacted by the cementitious materials, the water-cementitious materials ratio, the aggregate type and gradation, the curing (internal/external) provided, and the temperature history of the hardening concrete. In this study, restraint to volume change testing with rigid cracking frames (RCF) was used to directly measure and quantify the combined effects of all variables that affect the development of in-place stresses and strength in a specific application. The laboratory testing performed involved curing the concrete in the RCF under sealed, match-cured temperature conditions to simulate concrete placement in concrete bridge decks and mass concrete. Experimental results reveal that the use of low heat of hydration concretes, concretes that use fly ash and slag cement, and lightweight aggregate concretes (because of reduced modulus of elasticity and coefficient of thermal expansion), are very effective to reduce the risk of early-age cracking in these elements.

scholarly journals Cracking Safety Evaluation of Massive Concrete Structures

2011 ◽  
Vol 462-463 ◽  
pp. 1403-1408 ◽  
Author(s):  
A.A. Abdulrazeg ◽  
Parvin Khanazaei ◽  
Jamal Noorzaei ◽  
M.S. Jaafar ◽  
T.A. Mohammed ◽  
...  
Keyword(s):  
Concrete Structures ◽  
Safety Evaluation ◽  
Crack Development ◽  
Mass Concrete ◽  
Element Analysis ◽  
Massive Concrete ◽  
Rcc Dam ◽  
The Finite Element Analysis ◽  
Structural Stresses ◽  
Simplified Procedure

High temperatures generated in the concrete due to the hydration of cement induce thermal tensile stresses. If these stresses are not controlled, they cause cracks in mass concrete structures such as dams. Hence, the thermal and structural stresses needs to be checked against the possibility of cracking to evaluate the safety of the dam. This study deals with formulation and simplified procedure to predict the possibility of crack development in RCC dam. An existing 2-D code has been modified by implementing the crack prediction procedures. The applicability of the modified 2-D code has been shown by analyzing a real RCC dam called Zirdan dam situated in southeast of Iran. The predicted stresses which were obtained through the finite element analysis are examined against the crack development at Gaussian points and it was found that the dam is structurally safe.

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