Properties of concrete containing high-calcium fly ash artificial aggregate

The work aims to develop a concrete mixture with cold-bonded fly ash aggregate based on high-calcium fly ash and experimentally study its physical and mechanical properties. The results of experimental studies of concrete with artificial coarse aggregate based on fly ash from Berezovskaya Thermal Power Plant showed compressive strength of 28.92 MPa, flexural strength of 4 MPa, coefficient of linear thermal expansion of 14.5 * 10−6 K−1, modulus of elasticity of 16 *109 Pa, heat of hydration on the 10th day - 340 kJ/kg, shrinkage deformation of −1.8 mm/m. It has been established that heat treatment of fly ash aggregate for 8 hours at a temperature of 80 °C after 7 days of air storage did not positively affect the physical and mechanical properties of concrete. The compressive strength at the age of 28 days and the modulus of elasticity of the specimens with coarse aggregate after heat treatment were lower by 41% than that of the control mixture

Method for determining optimal overhaul service of centrifugal and axial pumps

The efficiency of pump operation mainly depends on the maximum permissible wear of the parts of their flow path. One of the factors determining the need for repair and restoration of centrifugal and axial pumps is the wear of parts that form the sealing and slotted gaps of the impellers. With an increase in the design clearances of the impellers, the leakage of liquid increases proportionally, and this worsens the energy performance of the pumps and, accordingly, leads to an increase in operating costs. At certain clearance values, the costs reach such a value that the pump operation becomes impractical. Therefore, when assessing the pump's performance, it is important to establish the wear limits of its parts. About a machine part, the limit state is a state in which its further operation is impossible due to an unrecoverable decrease in operating efficiency below the permissible level or the need for repair

Experimental evaluation of the throughput of the supply channel of pumping stations

The article experimentally studied the dynamics of sediment inflow into the fore chambers of pumping stations, revealed the intensity of silting, which affects the reliability and operation of the pumping station, and developed recommendations for improving its efficiency. The hydraulic parameters of the flow were evaluated by increasing the culvert capacity of the canal bed and ensuring a guaranteed flow of water to the pumping station with a minimum amount of sediment. The purpose of this work is to assess the state of its culvert capacity based on the results of field studies, which represent the water supply from the pumping station of the Karshi main canal