Basalt Rebar Design - About Basalt Rebar
What is Basalt rebar and what are its specs and characteristics.
Basalt Rebar is FRP Rebar
Basalt Rebar is a type of Fiber Reinforced Rebar (FRP).
The American Concrete Institute has produced a spec to recommend how to use FRP rebar. The spec is ACI 440.1R-06 .
The only reason ACI 440.IR-06 does not specify basalt rebar as an example of FRP rebar is that ACI 440.1R-06 was written a while ago before basalt rebar was invented.
A later written ACI spec (ACI 440R-07) does list basalt rebar as an example of allowed FRP rebar. It says... "Fibers commonly used to make FRP bars are glass, carbon, and aramid. Recently, continuous Basalt fibers have become commercially available as an alternative to glass fibers." It talks about Basalt FRP rebar all through the document and includes it in its various tables, but the key point is that it is classed as FRP. The term BFRP is often used instead of saying Basalt Rebar.
Basalt FRP rebar is approved as "natural fiberglass", meeting the certification specifications of ACI 440.6-08 and signed off the same as fiberglass FRP rebar. In doing so, the job will simply be overbuilt because the physicals of Basalt rebar are higher than fiberglass, falling between fiberglass and carbon fiber.
Basalt rebar can be placed to meet code requirements by using the
calculations and installation guidelines for fiberglass reinforcement of
concrete as defined in ACI 440.6-08. Recommendations for maximum
deflection and shear of concrete elements reinforced with fiber
reinforced polymer (FRP) rebar's are presented in ACI 440.1R-06 (2006)
"Guide for the Design and Construction of Structural Concrete Reinforced
with FRP Bars".
Basalt rebar has been tested at various universities and approved by the American Concrete Institute under ACI 440-10.
Basalt rebar is used according to ACI 440.1R-06.
The construction use is dictated by code 440.6-08.
It is specified by 440.5-08.
The conclusion from all the documentation is that Basalt rebar is FRP rebar and can be treated and approved as FRP rebar.
The spec for the basalt rebar that I use is...
Tensile strength: 130,000 psi
(900 MPa) (Worst case 116,030 psi)
Shear strength: 29,000 psi (200 MPa) (Worst case 26,100 psi)
Tensile modulus: 7,000,000 psi (48 GPa) (Worst case 6,526,698 psi)
Elongation at break: 2.3% (Worst case 1.6%)
Density: 1.9 - 2.1 g/cm3
To confirm that the basalt rebar from my Chinese manufacturer met the required tensile strength I had it tested by an ASTM accredited test house.