What is basalt rebar?

Rebars are backbone of construction industry. Rebars are made of steel and are in use ever since its innovated. Need is the mother of innovation. Problems like rebar corrosion led to various new type of rebar like epoxy coated bars, galvanized bars, stainless steel and frp rebars. Places where constructions are exposed to high levels of radio frequency radiations alongwith corrosion FRP and new entrant –rebar made of basalt are highly suitable.

Basalt rebars are made of volcanic rock called basalt- which is present abundantly in earh’s layer below crust

Basalt filaments are made by melting crushed volcanic basalt rock of specific mineral mixture at 1700 C, hot material is drawn through platinum  bushings and cooled to form filaments. This filaments are stronger then steel or FRP. Basalt rebar are made by pultrusion process using 80% basalt filaments and 20% epoxy as binder.

No chemicals are added to basalt during its manufacturing unlike FRP – so its environment friendly

Physical properties of basalt filaments like tensile strength, modulus of elasticity, temperature tolerance and resistance to acid & alkali damage are better than steel & glass fibers..

Basalt rebars have following advantages:

  1.    It does not corrode
  2.    Its stronger than steel and FRP rebars (tensile strength)
  3.    Higher chemical stability
  4.    Thermal expansion coefficient is similar to concrete.
  5.     Lighter than steel
  6.     Non conductor to heat & electricity.

                                                                                                                        Image courtesy: technobasalt


Basalt rebar clearly is ready to be used as a substitute for both steel and fiberglass rebar.  It is clear that steel in a concrete construction is a rust-spalling failure waiting to happen. Eventually moisture will get to steel wherever it is and no matter how well it is protected. It will then rust, swell, and cause the concrete to fail. With basalt rebar this issue is avoided forever.

The lack of spalling leads to one more advantage for basalt rebar. Construction codes call for concrete cover- spacing steel reinforcement at least 3 inches from the surface of the concrete. This is not necessary when using basalt rebar. A slab or panel can be made as thick or thin as is needed for structural integrity. If one inch of concrete is sufficient, a panel can be one inch thick with no risk of failure from spalling.

Comparison of physical properties- Steel, FRP and Basalt rebars.

ItemSteelGFRPBasalt rebar
Tensile strength(MPa)350-650500-900700-1300
Yield strength(MPa)280-420--
Compressive strength(MPa)350-650400-550450-550
Tensile elastic modulus(GPa)20035-4555-75
Coefficient of Thermal
expansion(*10-6 /C)-transverse

courtesey: pulwell composites co.Ltd


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