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.

Roller compacted concrete for the construction of hydraulic and hydroelectric buildings is a composite material, which consists of a binder, fine aggregate (sand), coarse aggregate (gravel or crushed stone), water and special additives that provide the desired concrete workability and impart the required concrete performance properties. Concrete mixture is prepared at from concrete mixing plants strictly metered quantities of cement, water, additives and graded aggregates, whereupon they are delivered to the site laying Mixer Truck and sealing layers with each stack layer. The advantages of roller compaction technology should include the reduction of construction time, which allows fast commissioning construction projects, as well as reduce the amount of investment required. One of the main problems encountered in the process of roller compaction of the concrete mix is the need to provide the required adhesion strength between layers of concrete. This paper presents a method for determining the strength of adhesion between the concrete layers of different ages roller compacted concrete using axial tension. This method makes it possible to obtain objective and accurate results with a total thickness of layers of compacted concrete of up to 300…400 mm. Results from this method, studies have shown that the value of strength between the concrete layers in addition to the composition of the concrete and adhesion depends on the quality and the parallel end surfaces of the cylinder-models, which are mounted steel plates for axial tension, as well as the state of the contact surfaces of the concrete layer. The method can be used to determine the strength of interlayer adhesion in roller compacted concrete, which are used in the construction of dams and other hydraulic structures.