Electrostatic Fiber-reinforced Concrete: New Opportunities in

Construction

Magomed Nakhaev

and Madina Salamanova

Chechen State University, Grozny named after A.A. Kadyrova, Grozny, Russian Federation

Grozny State Oil Technical University named after Academician M. D. Millionshchikov, Grozny, Russian Federation

Keywords: Construction, additive technology, electrostatic deposition, shaping frame, dry mix concrete, strong fibers.

Abstract: A new type of additive technology in construction is proposed - the so-called electrostatic molding of products

and structures from fiber-reinforced concrete. The peculiarity of the method is that the electrostatic deposition

of layers of dry concrete mix and reinforcing fibers on the shaping frame occurs without impact and noticeable

mechanical impact, in contrast to the coating technology, for example, with shotcrete. A layer of fiber-

reinforced concrete electrostatically deposited on the frame, after moistening and a short time delay, increases

the strength of the shaping frame. As the number of layers of concrete increases, the strength of the frame

increases, many times ahead of the load from an increase in the mass of concrete. Therefore, the shaping

frame can be made lightweight. This greatly simplifies its production. Therefore, reinforcing wire, wire mesh

and thinned coarse fabric made of hydrophilic fibers can be used for the frame of the structure. This is a

significant advantage of the new technology. When, after some time, the electrostatic concrete gains the

necessary strength, the structure is covered with glass fiber reinforced concrete from the inside using shotcrete.

It is necessary to carry out studies to determine the limits of applicability of the method in various areas of

construction.

1 INTRODUCTION

Apparently, the first truly additive technology in the

world was electroplating, discovered by B.S. Jacobi

in 1837. In electroforming, a new object is created

due to metal ions, which, under the action of an

electric field, purposefully move and settle on the

cathode, repeating its relief to the smallest detail (Dr.

Jacobi, 1840). In recent decades, additive

technologies based on the layer-by-layer growth of

three-dimensional objects using computer 3D

technologies have been increasingly used. This

applies to products made from a variety of materials.

One of the first additive technologies for builders

can be considered the technology of shotcrete, which

appeared at the beginning of the 20th century. This is

a productive method, but application of shotcrete

requires a solid wall, forming surface, or single-sided

formwork. Despite the fact that the concrete jet is

highly dispersed, upon impact, the high-speed jet

exerts strong pressure on the barrier (Bazhenov,

https://orcid.org/0000-0002-2589-6662

https://orcid.org/0000-0002-1293-7090

1984). Therefore, shotcrete is used where there is a

solid foundation - for repairing destroyed reinforced

concrete, strengthening the walls of pits, tunnels and

foundations, restoring hydraulic structures, etc. The

construction 3D printer that appeared at the end of the

20th century is another example of additive

technology in construction (Dominguez, 2013;

Fedorov, 2017). Despite all its shortcomings, the

construction 3D printer has already proven itself as an

economical way to build low-rise housing.

For more than half a century abroad, especially in

Germany and the USA, and later in Russia, tents and

tent coverings made of film-fabric materials have

been used. Their disadvantage is that awnings and

coverings in the form of technical fabrics require the

creation of a strong support contour with tension and

anchor devices for the stability of the structure against

strong winds and sometimes snow loads. When

studying such coatings from soft shells, it is

noteworthy that steel posts, solid or prefabricated

arches, guy wires and anchors, apparently, are much

Nakhaev, M. and Salamanova, M.

Electrostatic Fiber-reinforced Concrete: New Opportunities in Construction.

DOI: 10.5220/0011554300003524

In Proceedings of the 1st International Conference on Methods, Models, Technologies for Sustainable Development (MMTGE 2022) - Agroclimatic Projects and Carbon Neutrality, pages

44-47

ISBN: 978-989-758-608-8

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

larger in weight and cost than the technical fabrics for

tent covering themselves. Despite the often complex

technology of cutting technical fabric and its sewing

or welding (Patent RU 2622571, 2017).

Most of the coatings of large long-term structures

are built from rigid materials - from reinforced

concrete and precast concrete, and sometimes sheet

metal is used for membrane coatings. These materials

have long been widely used in construction practice

(Ledenev, 2016; SP 52-117-2008, 2008). The use of

prefabricated reinforced concrete slabs or metal

membrane coatings requires a well-equipped and

capital-intensive production base for its

implementation.

Technical solutions are known, based on the use

of mesh or fabric materials in the form of a shell, for

fixing the spatial shape of which the impregnation of

the shell material with a fixing composition is used.

For this purpose, curing compounds based on epoxy

resins, acrylic compositions and other compositions

of polymeric substances are used. For example, in

order to fix the shape of the shell impregnated with a

hardening composition, the contour elements of the

shell are made in the form of a sleeve from the shell

material, impregnated or filled with a hardening

composition (A.s. 935578 MKL E 04 B, 1982).

The disadvantages of using polymer curing

compositions to fix the shape of the shell are that this

technology is characterized by high labor intensity of

manufacture and insufficient rigidity and strength of

the cured shell contour. Since polymers have strength

indicators and modulus of elasticity many times lower

than those of steel. In addition, work with curing

compositions is strictly limited in time, since the

viscosity of the prepared compositions increases

rapidly over time. Working with curing compounds is

associated with unhealthy epoxy resins, acid

hardeners, plasticizers and solvents, especially during

formulation and curing.

2 RESEARCH METHODS

In Russia, a new type of additive technology has been

proposed - the so-called electrostatic molding of

products and structures from fiber-reinforced

concrete (Kokoev, 1997). The new technology gives

more creative freedom to the architect. It is

appropriate to note here that each new technology

sooner or later finds its niche in the construction

practice. For example, the prominent French

constructivist architect Le Corbusier in the first third

of the 20th century contributed to the widespread use

of concrete and glass in architecture with his projects

(Le Corbusier, 2004; Andrew Ayers, 2004). He is also

known worldwide for his pioneering work on precast

concrete. In 1914, Le Corbusier created and patented

the Dom-Ino House project, which was essential for

his creative biography. In fact, this was the very first

frame-type house project for serial construction. In

this project, he for the first time foresaw (together

with engineer M. Dubois) the great possibilities of

building from large-sized prefabricated reinforced

concrete elements - flights of stairs, floor slabs,

columns, etc.

But back to our topic. It is better to explain the

essence of "electrostatic" fiber-reinforced concrete

with an example. The selected objects are related to

the construction of hip roofs that crown centric

buildings, both in religious and civil buildings.

Coverings in the form of tents are also found in the

construction of cottages, exhibition and trade

pavilions, tourist centers and campsites. The tents can

be with double negative Gaussian curvature and

prismatic with zero or negative curvature (see figure).

Figure 1: Electrostatic fiber-reinforced concrete - new

opportunities in construction.

Electrostatic Fiber-reinforced Concrete: New Opportunities in Construction

Before moving on to the technology of the

method, it should be noted that the electrostatic

deposition of layers of dry concrete mix on the

shaping frame occurs without impact and noticeable

mechanical impact, in contrast to the coating

technology, for example, with shotcrete. The first

electrostatically deposited dry layer of fiber-

reinforced concrete, after moistening and a short time

delay, significantly increases the strength of the

shaping frame. As the number of layers of concrete

increases, the strength of the frame rapidly increases,

many times ahead of the load from the increase in the

mass of fiber-reinforced concrete.

a) the shaping frame of the prismatic tent, made

of wire reinforcement;

b) a prismatic tent, covered on the outside with

fiber-reinforced concrete, and on the inside

with shotcrete glass fiber-reinforced concrete;

c) pavilion wire frame with prismatic or conical

tent with negative Gaussian curvature; d) a

pavilion covered on the outside with fiber-

reinforced concrete, and on the inside with

shotcrete glass-fiber-reinforced concrete; h)

section A-A; g) view B.

1 - ribs of the shaping frame made of reinforcing

wire, 2 - inventory mast, 3 - base (floor) of the

structure, 4 - layers of concrete deposited by

electrostatic sprayers; 5 - thinned burlap, 6 - welded

or woven mesh, 7 - shotcrete layer of glass fiber

reinforced concrete.

Thus, the shaping frame can be made lightweight.

Therefore, for the manufacture of the framework of

the structure, it is possible to use reinforcing wire,

welded or woven wire mesh, duplicated with a

thinned coarse fabric (sparse burlap) made of jute and

other hydrophilic fibers. This reduces the labor

intensity and metal consumption of manufacturing a

shaping frame for low-rise buildings. In addition, the

method allows the use of a water-cement ratio close

to the theoretical one for a given concrete

composition. The optimal W/C value should provide

savings in cement without reducing the strength of

fiber-reinforced concrete. So, the shaping frame of

the building is made of reinforcing wire, the openings

are closed with steel welded or woven mesh. Outside,

thinned burlap made of jute and other hydrophilic

fibers is attached to the mesh. In this case, the cells in

the wire mesh are desirable from 30 mm in size and

above, and on the burlap the cells in the light should

be in the range of 5-12 mm. In the manufacture of a

shaping frame for a tent with a double negative

curvature, a flexible woven steel mesh is used,

thinned burlap is attached to the mesh from the

outside. Form limited areas of the surface of double

curvature, using the property of a woven mesh and

burlap to change the density of the weft and warp

threads.

The burlap is moistened for electrical

conductivity, the shaping frame is grounded, and

using a manipulator with electrostatic sprayers, the

burlap, together with the underlying mesh, is covered

with a dry concrete mixture containing reinforcing

fibers. The process of coating the shaping frame with

a dry mix is affected by the electrical resistivity of

cement particles and other components of the dry

mix. Of the industries where electrostatic technology

is used, it has been established by practice that the

area of optimal electrical conductivity of particles for

their electrostatic deposition (cement, fine sand, fly

ash, fiberglass, etc.) has a wide range - from 107 to

109 Ohm∙m (Petzold, 1990; Lagarias, 1960).

The settling of the dry concrete mix and the

wetting of the dry concrete mixture with water mist

must be separated by time and/or distance along the

building surface so that the high humidity air does not

reach the electrostatic sprayers. It is better to moisten

the applied layer of dry concrete with a cold fog

generator. Fog generators spray water with droplets

no larger than 50 microns. The cycles of coating with

a dry mixture and moistening with water are repeated

until the required thickness of fiber-reinforced

concrete is obtained. Between cycles, time delays are

made for the fiber-reinforced concrete to gain initial

strength.

3 RESULTS AND DISCUSSIONS

To prepare a dry mix of concrete, hydrophilic quick-

hardening Portland cement with fine mineral

additives and fibers is used. Instead of fine sand,

depending on the requirements for the structure and

its purpose, mineral powders are used - finely ground

waste from stone processing or ash and slag waste, fly

ash from electrostatic precipitators of power plants,

perlite powder, volcanic ash, cement dust from

electrostatic precipitators of cement plants and other

finely dispersed materials of natural and technogenic

origin (Nakhaev, 2015; Salamanova, 2019;

Salamanova, 2018).

For fiber-reinforced concrete, reinforcing fibers

are used - alkali-resistant glass, basalt, carbon

(Polyacrylonitrile; Hong, 2014), etc. The fibers must

first be freed from lubricants and other hydrophobic

substances. This condition provides good wetting

with water with the addition of surface-active

substances (surfactants) of the concrete mixture and

fibers and contributes to the work of capillary forces

MMTGE 2022 - I International Conference "Methods, models, technologies for sustainable development: agroclimatic projects and carbon

neutrality", Kadyrov Chechen State University Chechen Republic, Grozny, st. Sher

to compact the layers of fiber-reinforced concrete. If

water-soluble polymers are added to water to improve

the properties of fiber-reinforced concrete, then the

addition of surfactants is often not required, since

many water-soluble polymers themselves have good

surface activity. To increase the strength of some

objects after the strength of the electrostatically

deposited layers of fiber-reinforced concrete, the

structures can be covered with glass fiber reinforced

concrete from the inside using shotcrete.

4 CONCLUSIONS

Using the technology of electrostatic molding of

products and structures made of fiber-reinforced

concrete will give the following technical and

economic effect:

1. Reducing the labor intensity and metal

consumption of manufacturing shaping frames

of products and structures.

2. In the new technology, for the first time, it

became possible to regulate the W / C over a

wide range, regardless of the complexity of the

product shape. Through the use of a water-

cement ratio close to theoretical, savings in

cement should be achieved without loss of

concrete strength.

3. The use of "electrostatic" fiber-reinforced

concrete for the construction of low-rise

buildings in appropriate climatic conditions

will increase the durability of structures, as

well as reduce the cost of their construction.

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Electrostatic Fiber-reinforced Concrete: New Opportunities in Construction