Reinforced Concrete is a common building material for
construction of facilities and structures. While concrete has high
compressive strength, it has limited tensile strength. To overcome these
tensile limitations, reinforcing bars are used in the tension side of
concrete structures. Steel rebar has historically been used as an
effective and cost-efficient concrete reinforcement. Where not subjected
to chloride ion attack, steel reinforcement can last for decades without
exhibiting any visible signs of deterioration. However, it is susceptible
to oxidation (rust) when exposed to chlorides. Examples of such exposure
include coastal areas, sites where road salts are used for deicing,
locations where salt contaminated aggregates are used in the concrete
mixture, and sites where aggressive chemicals and ground conditions exist.
Where corrosion of rebar occurs, the resulting products have a larger
volume (2- 5 times) than the metal product from which they originally
derived. The concrete cannot sustain the tensile load developed from this
volume increase, and eventually cracks and spalls, leading to further
deterioration of the steel. The combination of ongoing deterioration and
loss of reinforcement properties ultimately requires potentially
significant and expensive outlays for repair and maintenance, and possibly
the endangerment of the structure itself.
History and research data has proven
that epoxy coated steel rebar is not an adequate answer to these needs,
although it is presently the most commonly used product for such
applications. Stainless steel will address corrosion issues, but is too
expensive. V-ROD with its superior tensile properties and built-in
corrosion resistance offers a unique and economically feasible reinforcing
rebar for such applications.
The V-ROD products offer the
following features / benefits when compared to steel rebar:
CORROSION RESISTANCE
- will not rust, and are impervious to the action of salt ions,
chemicals, and the alkalinity inherent in concrete.
LIGHTWEIGHT
- weigh approximately one-quarter the weight of an
equivalent size steel bar, offering significant savings in both
placement and use.
ELECTROMAGNETIC NEUTRALITY
- contain no metal, and will not interfere with the operation of
sensitive electronic devices such as medical MRI units or electronic
testing devices.
THERMAL INSULATOR
– highly efficient in resisting heat transfer, such as
from building exteriors to interiors.
Market Applications
Utilizing inherent features / benefits, V-ROD has cost effective
application as a concrete reinforcing bar in the following markets when
analyzed on a life-cycle cost basis:
Reinforced Concrete Exposed to Deicing Salts:
Parking structures; bridge decks; Jersey barriers; parapets; curbs;
retaining walls and foundations; roads and slabs on grade.
Structures Built in or Close to Sea water:
Quays; retaining wall; piers; jetties; caissons; decks;
piles; bulkheads; floating structures; canals; roads and buildings;
offshore platforms; swimming pools and aquariums.
Applications Subjected to Other Corrosive Agents:
Wastewater treatment plants; petrochemical
plants; pulp/paper mills; liquid gas plants; pipelines / tanks for
fossil fuel; cooling towers; chimneys; mining operations of various
types; nuclear power and dump plants.
Applications Requiring Low Electric Conductivity or
Electromagnetic Neutrality: Aluminum and
copper smelting plants; manholes for electrical and telephone
communication equipment; bases for transmission / telecommunication
towers; airport control towers; magnetic resonance imaging in hospitals;
railroad crossing sites, and specialized military structures.
Tunneling / Boring Applications Requiring
Reinforcement of Temporary Concrete Structures:
Structures including mining walls; underground rapid
transit structures and underground vertical shafts.
Weight Sensitive Structures:
Concrete construction in areas of poor load bearing soil conditions,
remote geographical locations, sensitive environmental areas, or active
seismic sites posing special issues that the use of lightweight
reinforcement will solve.
Thermally Sensitive Applications:
Apartment patio decks; thermally insulated concrete housing and
basements; thermally heated floors and conditioning rooms.
Designing with
Composite Rebar The mechanical properties of FRP reinforcing
bars differ from those of conventional steel rebar in a number of areas.
As a result, several issues arise in the development of a design
methodology for concrete structures reinforced with such bars. The general
design recommendations for flexural concrete elements reinforced with FRP
reinforcing bars are presented in the ACI 440.1R-06 entitled "Guide
for the Design and Construction of Concrete Reinforced with FRP Bars” as reported by the
American
Concrete Institute (ACI) committee 440.
The ACI 440
recommendations are based on principles of
equilibrium and compatibility, and the
constitutive laws of the materials. The new design philosophy adopted for
FRP bars used as reinforcement for concrete allows consideration to be
given to either FRP rupture or concrete crushing as the mechanism that
controls failure. It is based on limit
states design principles. An FRP reinforced concrete member is designed
based on its required strength, and then checked for fatigue endurance,
creep rupture endurance, and serviceability criteria. In most cases
serviceability criteria or fatigue and creep rupture endurance limits will
control the design.
Concrete
Protection Products, Inc.
627-C Graves Street w
Kernersville, NC 27284
Phone: 336-993-2461 w
Fax: 336-996-2732
Email:
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