No abstract

Owing to the increase in the volume of underground hydraulic construction and the placing of monolithic concrete linings in underground structures, it is necessary to mechanize this work and to improve the available equipment. Pneumatic concrete pumps are widely used underground for delivering concrete to the placement site. However, the lack of a filling device and mechanism for loading the concrete mix into the hopper lowers the efficiency of this mechanism and does not provide the necessary rate of performance. Attempts to adapt a belt conveyor for loading the concrete mix into the hopper did not work.During construction of the tunnels of the Nurek Hydroelectric Project the concrete mix has been loaded into the hopper of the pneumatic concrete pump through an intermediate hopper installed above the pump. The mix is delivered to this hopper by a skip with a capacity equal to the mix volume in the MAZ-205 dump truck. Control of the concrete entering the pneumatic pump from the overhead hopper was by a gate valve. In our case the concrete mix was charged into the pneumatic concrete pump directly from the lift skip without an intermediate hopper.