Abstract
Mathematical models for the simulation of the thermal evolution of roller-compacted concrete (RCC) dams during construction constitute an important tool for preventing excessive temperature rise, which may lead to cracking and losses of functionality. Here, we present a framework for the simulation of the thermal process. We define the boundary conditions of the problem using a careful description that incorporates the main heat exchange mechanisms. We adopt both a non-adiabatic and an adiabatic heat generation model for the simulation of the cement hydration. Our numerical framework lets us study the effect of the adopted heat generation model on the thermal field. Moreover, we study the influence of the weather conditions on the evolution of the hydration, and on the starting date of construction. Our simulations have shown that the hydration model has an important influence over the temperature field during the construction and the heat generation rate. Moreover, the hydration process and the temperature evolution are driven by the weather conditions. Once the next lift is cast, its thermal insulation effect makes the hydration take place under quasi-adiabatic conditions. As expected, dams built in cold months are prone to dissipate more heat than those built in warm seasons.
Highlights
Roller-compacted concrete (RCC) dams are especially prone to cracking while relatively new.The roller-compacted concrete (RCC) technology is economically profitable thanks to the high production rates, which are achieved by the use of high capacity placing and compaction equipment for construction
The simulations allow us to study the influence of the selection hydration model on the concrete temperature field and on the heat generation rate field
The simulation of the hydration reaction with a non-adiabatic hydration (NAH) model lets us study the influence of the environmental actions and the starting date of the construction on the hydration reaction and the concrete temperature evolution
Summary
Roller-compacted concrete (RCC) dams are especially prone to cracking while relatively new.The RCC technology is economically profitable thanks to the high production rates, which are achieved by the use of high capacity placing and compaction equipment for construction. Roller-compacted concrete (RCC) dams are especially prone to cracking while relatively new. The high construction velocity, together with the massive nature of the structure, makes the heat released during concrete hydration a key aspect in the design of these structures [2]. The high construction rates of RCC dams may lead to significant temperature rises. Such an increase occurs over the first days after setting when the stiffness of concrete is low and viscous effects are important. The temperature of the concrete is still relatively high in the core of the dam because the massive nature of the structure does not stimulate the dissipation of the hydration heat.
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