During cracks. The existence of cracks will

During the process of setting and hardening in concrete, the temperature profile shows a gradual nonlinear distribution due to the development of heat of hydration in cement. When Portland cement is mixed with water, heat is liberated. This heat is called the heat of hydration, the result of the exothermic chemical reaction between cement and water.

The heat generated by the cement’s hydration raises the temperature of concrete. During concrete construction, the heat is dissipated into the soil or the air and resulting temperature changes within the structure are not significant. However, in some situations, particularly in massive structures, such as dams, mat foundations, or any element more than about a meter or yard thick, the heat cannot be readily released. The mass concrete may then attain high internal temperatures, especially during hot weather construction, or if high cement contents are used.’Hydration of Portland cement pastes containing three types of mineral additive; fly ash, ground-granulated slag, and silica fume was investigated using differential thermal analysis, thermos gravimetric analysis (DTA/TGA) and isothermal calorimetric ‘by Pane, I. and W. Hansen 1? Prestressed concrete is one of the most reliable, durable, and widely used construction materials in building and bridge projects around the world.It has made significant contributions to the construction industry, the precast manufacturing industry, and the cement industry as a whole. It has led to an enormous array of structural applications, including buildings, bridges, nuclear power vessels, TV towers, and offshore drilling platforms2. The prestressed concrete of a box girder is large in volume, measured in unit per volume of concrete, and obviously has mass volume characteristics. After a large amount of hydration heat is produced, the heat doesn’t emit in a short time because the temperature difference between the internal and external of the structure is too large which causes large temperature stress to make the concrete crack3, 4. The cracks caused by thermal stress have characteristics of wide cracks. The existence of cracks will have an adverse effect on the bearing capacity and durability of structures.

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In recent years, the study of become important, and experience has been accumulated 5-7. Few researches has focused on single box single room, single box two room, single box three room, which are high significance to an ultra-wide section box girder. A special bridge in Qing Yijiang is a prestressed concrete continuous box girder bridge of curved four-line high speed passenger lane. Based on the analysis of Qing Yijiang bridge single box three rooms continuous beam zero block. During the construction of the project, the hydration field heat data was collected. In this paper, comparison of collected filed data and numerical simulation using ANSYS software is presented. 

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