Abstract
Similar to most of the other developing countries, Vietnam has national programs for industrial waste recycling including fuel, ash, and slag. In which, fly ash (FA) has been used commonly as a pozzolanic additive in the roller-compacted concrete (RCC) mixture for the dam construction of hydropower projects. This usage allows reducing the concrete cost, the hydration heat, and the thermal cracking during the construction process of the RCC. In this study, the optimal concrete mixture and the maximum temperature of the RCC dam were determined using the experiment planning method, Matlab, Maple 13, and Midas Civil. In addition, the mathematical model has been used to adequately describe the influence of the intensity concreting (IC) and the initial temperature of the concrete mixture (ITC) on the temperature regime of the RCC dam. The calculation of the temperature regime during the construction of the RCC dam of 45 m high and 1 m thick in Vietnamese climate conditions was performed with considering the IC and the ITC. As the results, the maximum temperature of the RCC dam was determined depending on the IC and the ITC. Calculation found that at IC = 0.6 m/day and ITC = 20°C, the maximum temperature in the central dam zone reached 36.38°C after 1800 hours from the beginning of construction. The results of the present study further support the safe and durable construction of the RCC dam in the future.
Highlights
Dam, which is one of the oldest artificial structures, has a responsibility for retaining water in small and large hydropower projects
In the case of this study, the roller-compacted concrete (RCC) properties were selected from the application of RCC technology in the construction of the hydroelectric power project in Vietnam and must possess the following requirements: (i) The workability of the RCC that measured by means of Vebe time device ranges from 15 to seconds; (ii) The 28-day compressive strength of the RCC is greater than MPa; (iii) The RCC has the water-resistant ability in the aquatic environment; (iv) fly ash (FA) is used to partially replace Portland cement (PC) in the RCC mixture (FA/PC = 1.5 by volume); and (v) The relative volume of entrapped air is no more than 1%
By using the Midas Civil computer program, the maximum temperature that related to the intensity concreting (IC) and initial temperature of the concrete mixture (ITC) occurring in the RCC dam body during construction time was determined with the values as shown in Table 12 and in Figures 5 – 9
Summary
Dam, which is one of the oldest artificial structures, has a responsibility for retaining water in small and large hydropower projects. In China, more than 10 million m3 of the RCC mixture are used annually in the construction of the hydro-technical structure and hydroelectric plants [1,2]. Like other developing countries and emerging economies, there has recently been a great demand for electricity in Vietnam, leading to an unprecedented boom in the construction of hydropower dam, which is facilitated by the great natural hydropower potential in large power plants. The application of RCC technology in the construction of the hydroelectric power project in Vietnam is accompanied by a number of serious problems. Previous studies reported that the use of fly ash (FA) as a cement substitution resulted in a reduction of hydration heat release, thermal cracking, and production cost of concrete [13,14,15]. FA has been widely used in different massive structures since [16,17,18]
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