Thermal curing, used for acceleration of concrete solidification, is an integral and most energy-consumed stage in precast concrete production technology. The most widespread way of its implementation is steam curing, for which boiler houses operating on mineral fuels are required. Methods of product heating by combustion products of various types of fuel, more often - natural gas, burned directly in the curing chamber, are also used. The use of these methods is accompanied by significant technological losses of heat and emissions polluting the atmosphere.
One of the ways to reduce the negative influence on the environment and improve the energy efficiency of the technological process of precast concrete producing is direct electric preheating of the concrete mix. The benefits of this approach will rise with the increasing of the share of electricity produced by "clean technologies" (using renewable energy resources, increasing the share of nuclear and thermonuclear energy).
Direct electric pre-heating is an element of the winter concreting technology, which makes it possible to pour the concrete mix on the frozen base and facilitates to the achievement of the critical strength of concrete before the appearance of water aggregative transition in it. The use of this technological approach in the heated manufactories conditions will make full use of its other features, promoting to the improvement of the energy efficiency of the production process and the quality of concrete, namely: reduction of energy consumption for heating of equipment elements (due to direct heating of the mixture); intensification heat evolution of concrete; ensuring the uniform heating of the mixture throughout the bulk, etc. However, in the precast concrete production technologies this method is not widely used. This is due primarily to the lack of practical experience in the implementation of this method (isolated cases), the lack of regulatory and technical basis of the narrow field under consideration, the imperfection of existing equipment for direct electric preheating of concrete mixtures.
The authors are developing a procedure for the incremental implementation of direct electric pre-heating of the concrete mixture into conventional factory technology, and working to improve the equipment and modes of its implementation.
|Affiliation of speaker||National Research Tomsk Polytechnic University|
|Position of speaker||PhD Student|
|Publication||Journal of Cleaner Production|