The Temperature Field in Mass Concrete with Different Placing Temperatures

Anh Kiet Bui,Trong Chuc Nguyen

doi:10.13189/cea.2020.080207

Abstract

Hydration heat of concrete mix has an important role in the process of temperature increase in mass concrete at an early age. Thermal stress caused by the temperature difference between the core and the surface of mass concrete is the main reason in making thermal cracks if the stress is larger than the tensile strength of concrete. The aim of this study is to investigate the effect of placing temperature on temperature distribution and thermal stresses of mass concrete. A proportion of concrete mix of interest is used for the thermal analysis of a mass concrete sample sized 8×6×3 m. The finite element Midas Civil program is used to conduct the three-dimensional thermal simulation. Four typical scenarios of placing temperature in the range of (15-30) ℃ of the concrete mix, which is commonly used in actual construction condition, are presented. The analysis results of temperature distribution and thermal stress indicate that the value of 30 ℃ of placing temperature according to the selected proportion of concrete mix may cause thermal crack in the mass concrete. The study gives a useful way for practical construction application to avoid the risk of thermal crack in mass concrete at an early age.

Highlights

Mass concrete are normally used for hydraulic structures, bridge, foundation of high-rise buildings, and etc
The temperature regime in mass concrete structures is affected by many factors, such as air temperature, wind speed, water temperature, intensity of solar radiation and shading effect, foundation temperature, and especially amount of hydration heat which is caused by the cement type and its content [4,5,6]
If the tensile stress is larger than the tensile strength of the mass concrete, thermal cracks form on the surface of the concrete structure, especially at the early age

Summary

Introduction

Mass concrete are normally used for hydraulic structures, bridge, foundation of high-rise buildings, and etc. One of the significant factors affecting the stress-strain state of the concrete mass during construction and operational process is temperature effect due to hydration heat of cement [1,2,3]. The temperature regime in mass concrete structures is affected by many factors, such as air temperature, wind speed, water temperature, intensity of solar radiation and shading effect, foundation temperature, and especially amount of hydration heat which is caused by the cement type and its content [4,5,6]. High temperature gradient occurring during the construction may cause significant tensile stresses and lead to thermal cracks [7,8,9]. In order to avoid the formation of thermal cracks, a general condition is that the temperature gradient ΔT should not exceed 20°C [10]

Objectives

Methods

Results

Conclusion