|GLASSFIBER REINFORCED CONCRETE PROPERTIES
Modern times require introduction and use of
new construction materials and procedures. One way to create a new
material is to reinforce an existing one. For instance, the cost-effectiveness
and strength properties of reinforced concrete are better than those
of plain concrete. One of the most advanced types of concrete reinforcement
is fiber reinforcement, which produces a new material called fiber
reinforced concrete. Classes of fiber reinforced concrete differ
by the type of fiber strings used. The most common sorts of fibers
for concrete reinforcement are:
• steel fiber,
• alkali-resistant glass fiber,
• conventional glass fiber, and
• synthetic fiber.
Glass fiber reinforcement had proved to be the
most economically and technologically feasible solution.
Glassfiber reinforced concrete (GRC) is a variety
of fiber reinforced concrete and is manufactured from fine grained
concrete (concrete matrix) and reinforcing glass fiber strings that
are uniformly distributed across the concrete volume of the product
or its specific parts. The collaboration of concrete and fibers
is ensured by bonding along their surfaces, providing a huge fiber-and-concrete
contact area (which may range from 10,000 to 50,000 sq.m depending
on the end-product application). This results in brand-new properties
of the GRC material.
Large-scale production and use of glassfiber reinforced concrete
panels is important for construction cost reduction, labor saving,
and enhancing the functional reliability and durability of structural
Dispersed reinforcement does not only increase
the strength properties of concrete, but essentially improves the
structures’ performance characteristics, such as resistance to dynamic
impacts, temperature, humidity, attrition, and other loads, which
makes the manufacture and use of GRC structures particularly effective.
Depending on their application, glassfiber reinforced
concretes can be divided into structural, waterproofing, architectural,
and special GRC. According to their application, glassfiber reinforced
concretes can have a variety of specific properties attainable by
different combinations of short-fibered and long-fibered components
of glass reinforcement and by the choice of the manufacturing technique.
GRC has exceptionally good processing properties,
can be molded into virtually any shapes, has a high bending strength,
impact resistance, elasticity, crack resistance, and waterproofing
capacity, and can have a decorative surface finish when necessary.
Glassfiber reinforced concrete presents architects
with such means of implementation of their designs which is unrivaled
by any other material in terns of moldability, capability to replicate
a surface geometry, and lightness. Glassfiber reinforced concrete
is lightweight, easy to handle, cheap to install and transport,
fire resistant, has a low water permeability level, and reduces
loads on a building’s bearing structure leading to significant savings
in superstructure and foundations, which is especially useful for
reproduction and renovation.
GRC structures can have the following types of
Fiber reinforcement, when a structure is only reinforced with glassfiber
strings uniformly distributed across the concrete of a component
or its part;
Combined reinforcement, when a product is reinforced with both steel
rods or wires and glassfiber strings uniformly distributed across
the volume (or section) of a component.
GRC is used in thin-walled members and structures
of buildings and installations where dead load reduction, better
cracking resistance, ensuring the waterproofness and durability
of concrete (especially in corrosive environments), improved impact
ductility and abrasion resistance, radio transparency, and enhancing
the architectural plasticity and environmental safety are the critical
GRC panels can be used as customized structural
members in special purpose buildings, as modular units in serial
construction, or as cladding panels in refurbishment work.
Two solutions are possible in any particular
• integrally stiffened single-layer
• permanent formwork with subsequent casting.
Specially tailored metal, wood, plastic, or polyurethane
molds provide embossed surface finishes ranging from simple designs
to free forms, heraldic symbols, or decorative dressing. Using a
white or gray cement base with some additions of inorganic dyes,
sand, and other aggregates, a wide range of colors and finishes
can be created.
The thinness of the finishing coat (not thicker
than 5 or 6 mm) minimizes the material costs. A thin finishing layer
imitating natural stone, slate, or stoneware tiles is made on a
bonding cement panel that forms part of the bearing frame structure.
The architectural flexibility of glassfiber reinforced
concrete provides a way to avoid the monotony of painted steelwork
or plastic and the ponderosity and limited moldability of traditional
Apart from cladding panels, an important advantage
in building reproduction and renovation is the possibility to replicate
historic features. GRC is also indispensable for making window surrounds,
door portals, cornices, sunscreens, and other products.
Glassfiber reinforced concrete is superior for
different types of roofing. It can imitate traditional roofing materials
such as slate or clay tiles but unlike these materials it is neither
brittle nor heavy. On sloping roofs, GRC can reproduce both the
appearance and the surface finish of natural slate. It can be fixed
with usual slating nails without having to drill nail holes, because
GRC is tough and cracking resistant.
GRC is playing a major role in designing urban
leisure facilities in terms of aesthetics of building projects and
architectural moldings and features. It can be used to arrange picturesque
decorative pools, fountains, seatings, planters, balustrades, kiosks,
etc. GRC architectural features have a more attractive appearance,
because GRC can reproduce any shape, geometry, and surface finish
to provide improved compatibility with the surrounding landscape.
GRC plaster is exceptionally strong and resistant to cracking and
Glassfiber reinforced concrete is highly resistant
to chemicals, including urban pollutants and salt solutions. It
also has good acoustic properties and is stain, rot, corrosion and
fire proof. Molded into various complex configurations, GRC products
can be used in civil engineering to build highways, water ducts,
storage reservoirs, wells, and tunnels.
Glassfiber reinforced concrete can also be used
to manufacture large-bore pipes and can be reinforced by either
chopped fibers or alkali-resistant glassfiber nettings.
The small thickness of pipe walls and the absence
of union joints make it possible to decrease the trench size and
the filling volume. Such pipelines can be laid under high traffic
load roads, because GRC is long-lasting and has exceptional strength
performance when alkali-resistant glassfiber is used as the reinforcing
In bridge construction, glassfiber reinforced
concrete is ideal for manufacture of parapet parts and noise barriers,
which can be quite long and still remain lightweight. In addition,
GRC ensures a better protection for steel reinforcement and has
a higher resistance to ingress of chlorides than conventional concrete
of the same thickness.
Due to the light weight of products and the thinness
of walls, GRC can be used for manufacture of ducts and water conduits
to replace short and heavy-weight cast concrete components. A threefold
reduction of product weight facilitates the erection of drainage
and irrigation systems on uneven terrains. Besides, the cost of
construction of underground water and cable ducts is reduced due
to the smaller number of supports required.
GRC components of cable, drainage and irrigation
channels can also be used as permanent formwork. In this case, GRC
panels are fitted before concrete is placed and their function is
to form a smooth-faced interior profile of the channel and thus
eliminate the necessity of using a complicated temporary formwork.
Technological advantages over plain and armored
Many of the technological and economical advantages
of GRC are unrivaled by traditional materials. Therefore, its main
distinctive features are:
Improved cracking resistance, impact ductility, abrasion resistance,
freeze-thaw durability, and weathering stability;
possibility to use more efficient structural solutions than in
case of conventional reinforcement, e.g. the possibility to use
thin-walled panels and structures without any reinforcing rods,
mesh reinforcement, distribution bars, or crosswise reinforcement;
possibility to minimize or entirely avoid steel rods, which is
particularly important when cost is critical;
and energy saving in reinforcement installation; a greater degree
of mechanization and automation in manufacture of fiber-concrete
products such as prefabricated thin sectional insulation, thin
slabs, ribbed roof slabs, jointless and solid panel floors of
industrial and communal buildings, permanent formwork structures,
Note 1. GRC components
without steel armoring may be used in structures that are mainly
Dynamic pressures, abrasion, bursting, and atmospheric action;
loads with eccentricity of normal force, such as in space frame
loads, provided that brittle failure is excluded.
Note 2. Structural
GRC panels must have combined reinforcement.
PROPERTIES OF TOP-QUALITY GRC
|Charpy impact strength
|Modulus of rupture
Axial tension strength:
- elastic limit
- ultimate strength
|Strain to failure
|(600-1200)·10-5 or 0.6-1.2%
- interlaminar shear strength
- in-plane shear strength
|Thermal expansion coefficient
|Water resistance as per GOST 12730
|Coefficient of permeability
|Freeze-thaw durability as per GOST 100600
|Better than that of concrete
|Noncombustible (no flame propagation)
Acoustic absorption at 15 mm thickness
The following formula can be used to convert
kg/cm2 to MPa:
The process flow diagrams, the preliminary
work list, and the quality control and safety measures (depending
on the manufacturing technique and materials used) are specified
in the Departmental Building Regulations (VSN) named Fiber-Concrete
Structures Engineering and General Provisions for Manufacturing
Procedures, VSN 56-97, Moscow 1997.