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 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.  

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 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 The Study on Cracking Strength of AIJs to Release the Early-Age Stress of Mass Concrete

2015 ◽  
Vol 2015 ◽  
pp. 1-8
Author(s):  
Xiaogang Zhang ◽  
Chengqiang Wang ◽  
Shuping Wang ◽  
Feng Xing ◽  
Ronghua Zhu
Keyword(s):  
Analytical Model ◽  
Concrete Structure ◽  
Present Model ◽  
Early Stage ◽  
Early Age ◽  
Mass Concrete ◽  
Element Analysis ◽  
Construction Period ◽  
Early Stress ◽  
Fracture Theory

This paper aims to theoretically and numerically assess the effect of setting artificial-induced joints (AIJs) during construction period of a mass concrete structure to release the early-stage thermal stress. With respect to the coupling influences of various factors such as size and boundary of AIJs, an analytical model for its cracking strength on the setting section of mass concrete is proposed based on double-parameter fracture theory. A kind of hyper-finite element analysis (FEA) for many array AIJs in simplified plane pate is also presented by using bilinear cohesive force distribution. The results from the present model and numerical simulation were compared to those of experimental data to prove the efficiency and accuracy of the analytical model and FEA. The model presented in this study for the cracking strength of AIJs provides a simple useful tool to accurately evaluate how many early stress AIJs reduced. The theoretical solution and FEA results could also be significantly contributed to find the “just” and “perfect” release of the temperature stress and to improve the design level of AIJs in mass concrete structure.

Exploration for Maintenance Measures and Temperature Control of Mass Concrete Pile Caps

2013 ◽  
Vol 671-674 ◽  
pp. 2032-2037
Author(s):  
Chen Ming Yu ◽  
Jun Tong Qu ◽  
Zhi Hong Ran ◽  
Hao Ying ◽  
Fan Tao Meng
Keyword(s):  
Temperature Variation ◽  
Temperature Control ◽  
Concrete Structures ◽  
Heat Of Hydration ◽  
Bridge Engineering ◽  
Mass Concrete ◽  
Construction Time ◽  
Crack Control ◽  
Thermal Cracks ◽  
Pile Caps

Distress in mass concrete is a problem in highway and bridge engineering. These mass concrete structures craze not by external loads, the temperature variation caused by heat of hydration and the temperature stress caused by concrete shrinkage are the main causes () for the leaks [1]. Therefore, the thermal stress and the temperature control have significant meaning in the mass concrete structures. Thermal cracks will break the structure globality and also decrease the durability of the structures during the construction time. In addition, the temperature variation will have a remarkable affection on the stresses variation of the structures during the service time [2]. This paper will discuss the temperature monitoring and the crack control projects of the mass concrete based on the cushion cap of an extradosed cable-stayed bridge which is being constructed.

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