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 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. 

Causes and Control Measures of Mass Concrete Crack of High-Rise Building Basement Foundation Slab

2010 ◽  
Vol 163-167 ◽  
pp. 1609-1613 ◽  
Author(s):  
Hui Hong Feng ◽  
Xi Wang
Keyword(s):  
Control Measures ◽  
Mass Concrete ◽  
Construction Process ◽  
Construction Stage ◽  
Foundation Slab ◽  
High Rise ◽  
High Rise Building ◽  
Concrete Crack ◽  
And Control

This paper discusses that the causes and the corresponding control measures of mass concrete crack in the construction stage. And through the analysis of engineering example, it describes the application of the control measures of mass concrete crack in the basement foundation slab of high-rise building in construction process, and analyses the construction effect of its.

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.

The Measurement of Concrete Temperature Distribution Based on VB

2014 ◽  
Vol 599-601 ◽  
pp. 1154-1157
Author(s):  
Xu Hui Yao
Keyword(s):  
Large Volume ◽  
Concrete Strength ◽  
Simulation Software ◽  
Control Measures ◽  
Mass Concrete ◽  
Various Boundary Conditions ◽  
Concrete Temperature ◽  
Prediction And Control ◽  
And Control

Based on the study of the rule and the optimization of the mass concrete temperature development, we developed a set of large volume concrete under various boundary conditions temperature prediction and control simulation software, to lay the foundation for the development of the law of large volume concrete strength, to achieve the optimization ratio of concrete and reasonable selection of the temperature control measures,to control the temperature change of concrete, to ensure the quality of concrete effect!

Knowledge and Awareness of Dengue Fever

2018 ◽  
pp. 219-222
Author(s):  
Y. Arockia Suganthi ◽  
Chitra K. ◽  
J. Magelin Mary
Keyword(s):  
Dengue Fever ◽  
Prevention And Control ◽  
Control Measures ◽  
Infection Transmission ◽  
Standard Guideline ◽  
The World ◽  
Different Types ◽  
Prevention And Control Measures ◽  
Dengue Prevention ◽  
And Control

Dengue fever is a painful mosquito-borne infection caused by different types of virus in various localities of the world. There is no particular medicine or vaccine to treat person suffering from dengue fever. Dengue viruses are transmitted by the bite of female Aedes (Ae) mosquitoes. Dengue fever viruses are mainly transmitted by Aedes which can be active in tropical or subtropical climates. Aedes Aegypti is the key step to avoid infection transmission to save millions of people in all over the world. This paper provides a standard guideline in the planning of dengue prevention and control measures. At the same time gives the priorities including clinical management and hospitalized dengue patients have to address essentially.

The Mediterranean Action Plan: A Regional Approach to Pollution Control

1986 ◽  
Vol 18 (9) ◽  
pp. 197-205
Author(s):  
Lj Jeftié ◽  
L. J. Saliba
Keyword(s):  
Mediterranean Sea ◽  
Action Plan ◽  
Control Measures ◽  
Industrial Wastes ◽  
Pollution Monitoring ◽  
Environmental Preservation ◽  
Agricultural Pesticides ◽  
The Mediterranean ◽  
A Prospective Study ◽  
And Control

Increasing concern over the deterioration of the Mediterranean sea as a result of increasing pollution by untreated sewage and industrial wastes, agricultural pesticides and fertilizers and oil discharges, led to a series of meetings between 1970 and 1974, and finally to the UNEP-sponsored Mediterranean Action Plan, adopted by governments of the region in 1975 and ongoing since that time. The legal component of the Plan includes a framework Convention and four protocols; the environmental assessment component (the MED POL programme) consists of national pollution monitoring programmes, and research projects conducted by Mediterranean institutions; the environmental management component consists of the Blue Plan (a prospective study combining socio-economic development with environmental preservation) and the Priority Actions Programme (a series of sub-region sectoral projects in defined areas). The Plan has been financed by Mediterranean States since 1979, and is managed by UNEP with the cooperation of other competent UN Agencies. During the last ten years, activities undertaken have improved knowledge of the state of pollution of the Mediterranean sea, and facilitated joint regional action in the form of preventive and control measures.

An evaluation model of 2019-nCoV prevention effectiveness based on immigration data in China (Preprint)

2020 ◽  
Author(s):  
Qiangsheng Huang
Keyword(s):  
Prevention And Control ◽  
Time Window ◽  
Evaluation Model ◽  
Control Measures ◽  
Related Data ◽  
The Face ◽  
Prevention And Control Measures ◽  
And Control ◽  
Best Fit

BACKGROUND As of the end of February 2020, 2019-nCoV is currently well controlled in China. However, the virus is now spreading globally. OBJECTIVE This study aimed to evaluate the effectiveness of outbreak prevention and control measures in a region. METHODS A model is built for find the best fit for two sets of data (the number of daily new diagnosed, and the risk value of incoming immigration population). The parameters (offset and time window) in the model can be used as the evaluation of effectiveness of outbreak prevention and control. RESULTS Through study, it is found that the parameter offset and time window in the model can accurately reflect the prevention effectiveness. Some related data and public news confirm this result. And this method has advantages over the method using R0 in two aspects. CONCLUSIONS If the epidemic situation is well controlled, the virus is not terrible. Now the daily new diagnosed patients in most regions of China is quickly reduced to zero or close to zero. Chinese can do a good job in the face of huge epidemic pressure. Therefore, if other countries can do well in prevention and control, the epidemic in those places can also pass quickly.

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