ANALYSIS OF THE RELEVANCE OF CONTOUR CONSTRUCTION TECHNOLOGY IN MODERN REALITIES

АНАЛИЗ АКТУАЛЬНОСТИ ТЕХНОЛОГИИ КОНТУРНОГО СТРОИТЕЛЬСТВА В СОВРЕМЕННЫХ РЕАЛИЯХ

Шаврин Руслан Махирович

студент, Национальный Исследовательский Московский Государственный Строительный Университет,

РФ, г. Москва

Мирзалиев Ислам Ахмедханович

студент, Национальный Исследовательский Московский Государственный Строительный Университет,

РФ, г. Москва

Юдина Ирина Ивановна

преподаватель, Национальный Исследовательский Московский Государственный Строительный Университет,

РФ, г. Москва

ABSTRACT

The article deals with the technology of contour construction, printing methods, compositions of mixtures and additives to them, examples of practical application of 3D printers, advantages and disadvantages of this technology, as well as prospects for its further development and implementation in the construction process.

АННОТАЦИЯ

В статье рассматривается технология контурного строительства, способы печати, составы смесей и добавки к ним, примеры практического применения 3D принтеров, преимущества и недостатки данной технологии, а также перспективы дальнейшего ее развития и внедрения в строительный процесс.

Keywords: additive technology, 3D printing, technology of contour construction, selective sintering, mixture, laser stereolithography, layered extruding.

Ключевые слова: аддитивная технология, 3D-печать, технология контурного строительства, селективное спекание, смесь, лазерная стереолитография, послойное экструдирование.

Construction is an important industry that creates and directly affects the economy. It provides a huge number of jobs for workers around the world. Like any other industry, the construction industry is improving its technologies and it is changing significantly over time. These processes occur gradually, new materials appear that differ significantly in their comfort, environmental friendliness, cost-effectiveness, durability, as well as new technologies that make the process of creating projects more automated. Thus, it becomes possible to reduce the amount of labor force, to reduce the number of injuries at work, to reduce the cost of projects and to speed up construction work. An example of contour technology is the use of additive technology in building construction using construction printing. Contour construction is the process of creating three-dimensional objects by using special equipment - a printer based on a digital 3D model of the object. This technology is used in many areas: robotics, mass production, medicine, military industry and in many others.

The construction of buildings and structures by this technology is a promising direction in construction. To date, there are many types of such printing: prototyping by deposition, selective laser sintering, laser stereo lithography, electron beam melting, production of models using lamination, technology of color 3D printing by gluing powder, the basis of which is gypsum. All of them differ in the type of material and methods of its application.

The most interesting are the following printing methods:

• Selective sintering is a sintering method consisting in melting special ink due to the action of a point laser beam. Ink often consists of quartz sand. After focusing, the lens of the mechanism melts the material located under it, performing a spike.

• For laser stereo lithography, a laser installation with a bathtub having a special table is used. This bathtub is filled with a liquid composition capable of photo polymerization under the action of a laser beam. Sintering of the material is carried out in layers, moving the laser beam along the intended trajectory. After finishing the first layer, the bath table is lowered by a step and the formation of the next layer is performed. Like selective sintering, this method is environmentally friendly, since solar energy is used, and sand serves as the working mixture.

• Layer-by-layer extrusion is currently the main printing method performed by most construction printers. The method is a process of extrusion of a special fast-hardening mixture based on concrete with the presence of various additives that improve the characteristics of the structure being erected. Each new layer is applied by the printer on top of the previous one, due to which the process of forming the structure takes place.

The composition of mixture in the method of layer-by-layer extrusion can be different and it depends on the desired characteristics of the structure. Its basis is often a fast-hardening concrete, capable of being used with various types of fibers and rods. The solidification of such a mixture occurs within an hour, the original form is well preserved. Such a mixture has a small shrinkage. The main additive to it is fiber, which is a material used as a reinforcing component to improve the properties of the concrete mixture: the compressive strength increases significantly, as well as the tensile strength and bending strength; thermal stability increases, the pace of construction of structures is accelerating and material consumption is reduced.

Several types of fiber can be used. Each has its own characteristics:

• Glass increases impact resistance and density.

• Polypropylene increases plasticity, wear resistance, water resistance, it helps to reduce weight.

• Basalt is an electrical insulating material, it does not burn, it is an environmentally friendly material.

• Steel helps to reduce the thickness of walls and mass without loss of load-bearing characteristics, steel increases resistance to loads and improves waterproofing of structures.

Today there are many types of construction printers designed and assembled in different countries. Each of them is unique and able to perform a narrowly focused job. Some of them are listed below:

1. Shanghai Company “Shanghai Win Sun” has invented a stationary printer installed outside the contour of the building and it has dimensions that allow the construction of five-story structures.
2. The Dutch Company “Additive Cyber Industries” has invented a 3D printer capable of erecting walls using a special type of concrete. This construction mixture is suitable for repeated processing; the use of this mixture can reduce carbon dioxide emissions by 32% and speed up printing due to rapid drying.
3. The French printer “Yhnova” has demonstrated the capabilities of the 3DBatiPrint construction system. Unlike standard construction 3D printers, the French printer “Yhnova” is capable of printing with mounting foam, not just with cement mixtures. In other words, it prints insulation, only then concrete is poured until a monolithic structure is obtained. The location of the nozzle is carried out using an industrial manipulator.
4. The American Company “Apis Cor” together with six Russian companies implemented a joint project in Moscow in 2016. Using a 3D printer designed by the American company, they managed to print a residential building in 24 hours. The construction took place in winter and that slowed down the process. Layers were built up by means of additive technology. The area of the building was 38 square meters. It is important to note that the house was printed as a whole and that happened for the first time in Russian construction practice, and it was not assembled in parts from pre-printed panels.

Let us consider the advantages of this technology:

1. Using the contour method of construction will allow you to move to buildings of non-standard shapes, with curved contours and lines, that is a difficult task for current construction methods.

2. Ultra-precise construction with little time - a machine can build a residential building with an area of 38 square meters in less than 8 hours, and the cost will be approximately $64,000.

3. Reducing the complexity of the work and minimizing the use of labor force.

4. Reduction of construction waste. Most concrete mixtures are environmentally friendly.

5. Reducing the risk of injury to workers in the process of work.

It should be noted that the technology of contour construction, being new, has a number of unresolved problems. Let us consider the disadvantages of this technology:

1. The high cost of equipment, the complexity of its maintenance and installation. Such a progressive technology currently has a high price. The cost reduction will occur only if the contour construction proves its practicality.

2. The lack of the possibility of autonomous construction at all stages. There is a problem with printing the roof due to its geometric complexity; because of this, roof is made by the standard method, using the workers' labor.

3. The impossibility of erecting horizontal structures in a limited working area. Vertical fittings prevent some types of printers from applying new layers.

4. At the moment there is no regulatory and legislative framework for the construction of buildings by contour construction, which creates strong restrictions in its application for mass development and because of these restrictions large construction companies do not purchase printers. These devices are currently used only in low-rise and small-sized construction.

5. The lack of a universal mixture for printing. Each manufacturer uses different concrete mixtures, constantly changing the composition and their ratio.

6. There are high requirements for the composition of the concrete mixtures. It is necessary to comply with the conditions of strength, rigidity, fire resistance, environmental friendliness, which ultimately drives up the cost.

7. The dimensions of the building under construction directly depend on the size and capabilities of the printer.

8. This technology is limited to the warm season.

Conclusions:

1. The introduction of this technology will positively affect the speed of the process of bringing new developments and products to the market, which will eventually make 3D printing of houses the main method of production. At the moment, the foundation is being laid on which companies will be able to develop new technologies that allow them to create innovative products, improve the characteristics of goods and increase their efficiency.
2. The construction sector, like any other sector, does not stand still and it constantly developing. Over time, more and more high-tech techniques will appear. 3D printing of buildings and structures in a short period of time was able to interest a large number of construction companies. Its prospects are promising, but we should not forget the significant problems that stand in the way of its development. It is necessary to continue the introduction of contour construction into mass production.
3. The American Company “Jabil Inc.”, having conducted a study, found out that more than 85 percent of companies already using 3D printers have plans to expand the areas of application of additive technologies in construction industry at least two times and more than 40 percent of companies have plans to expand the areas of application of additive technologies in construction industry more than five times.

Chart 1. Development prospects

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