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Abstract
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| An agent-based model considers a system as a collection of autonomous entities called agents. Each independent agent behaves on the basis of a set of rules and, depending on the system circumstances, may act in different ways. This paper describes an agent-based model to simulate the early and intermediate stages of cement hydration, taking into account the effects of curing temperature and water-cement ratio. With this approach, calcium silicate phases are considered as agents of the system, while time and water play the role of activator agents and temperature acts as a determiner agent. This computational model aims to describe the behavior of these agents individually, in order to simulate the dynamic of the hydration process of cement. A model based on agents for the cement hydration allows one to analyze the degree of hydration and the formation and growth of the C-S-H gel as functions of time. Regarding the influence of curing temperature on hydration kinetics, experimental results show two opposite effects: the reaction rate increases when temperature rises, but the density of the hydration products also increases at higher temperatures, resulting in a slower permeation of free water through the hydration products. Combining these two effects, the hydration rate is therefore lower during the late period at elevated temperature. Concerning the water-cement ratio, experimental studies have demonstrated that a higher proportion leads to a higher hydration rate from the middle period of hydration onwards, while it scarcely affects hydration rate in the early stages. These effects on hydration kinetics are reproduced by the agent-based model presented here. The model validation is conducted by comparison between computed and experimental results achieved on ordinary cement pastes with different water-cement ratios cured at various temperatures (ranging from 20ºC up to 50ºC). The thermal effects on the density of different cement pastes are analysed with the thermogravimetric analysis (TGA) and the derivative thermogravimetric analysis (DTG) curves. Such techniques will be used to determine the amount of non-evaporated water presented in the pastes, as well as to give effective information about the degree of hydration of the system at certain time. | |
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International
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Si |
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Entity
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Instituto Eduardo Torroja |
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Place
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Madrid |
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Pages
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Reference/URL
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ISBN- 978-84-7292-399-7 |
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Publication type
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Libro de Abstracts |