The technology for applying guncrete is now extensively used. The protection of furnaces using such concretes, as well as industrial buildings and plant using various cement-sand compositions or ash-slag mixtures, is possible by employing a highly effective method and equipment which produce guncrete of the desired properties and which make the best possible use of the raw materials.The extensive introduction of guncreting requires the investigation of the parameters that affect the movement of the mortar-air mixture. The effectiveness of guncreting is largely determined by the parameters of the movement of these mixtures in the channel of the mixing nozzle of the g~an, since it is a closed design element in the production chain in which the mixture is created and from which it then flows.The parameters influencing the flow cycle are: the velocity of the mortar-air mixture in the channel; the volume of air consumed, and the density of the mixture. The flow rate is selected taking account of the optimum consumption of air and nozzle diameter. Regulation of the flow rate is done by using mixing nozzles of different diameters and by maintaining the necessary air consumption. Ensuring the given velocity of the mortar-air mixture in the channel is effected by the choice of the cross sectional area of the material duct feeding in the air for pneumatic transporting of the dry (up to 2% moisture) material at a fixed pressure.To determine the parameters for the mortar-air flow we specify conditions satisfying the inequalities:where %r is the critical velocity of the dry material in' the duct for which there is no clogging, m/sec; %, velocity of the mortar in the channel of the mixer nozzle, m/sec; COa.w, velocity of the mixture in the channel for which rapid abrasive wear is absent, m/sec; Pu.m, pressure of the guncrete jet for which the maximum efficiency of material use is achieved. MPa; pg, pressure of the guncrete jet for which there is rapid breakdown of the freshly applied guncrete coating, MPa; Qa, volume consumption of 3 * air in m /sec; Qmin, minimum permitted air consumption ensuring pneumatic transportation of the dry material in m3/sec. The critical velocity of the material at the end of the material duct before reaching the nozzle is determined by the expressionwhere c is an experimental constant taking account of the tendency of the material to caking, the presence of moisture, and the complexity of the trace (for easily aerated mixtures c = 0:.075 [1]), ,%1 is the mass concentration of material, kg/kg; ,a N *Calculations were made with air parameters in normal conditions (p = 0.1013 MPa, T = 273 K).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.