Frequently Asked Questions
A. mateenbarTM is one of the highest strength composite rebars available, with a tensile strength of over 1000 MPa, which is almost at the theoretical limit for an ECR-glass reinforced composite rebar. This is over twice the tensile strength of steel rebar, which is typically 400 to 500 MPa.
A. The modulus of mateenbarTM is lower than steel. mateenbarTM is over 60GPa where the modulus of steel is 200GPa.
A. The lower modulus can be overcome as mateenbar™ is corrosion resistant, therefore it does not require large concrete coverage to provide protection, so can be placed much closer to the surface.
The increased distance from the neutral axis increases the sectional modulus. Also, due to the non-corrosive nature of mateenbar™ the crack-width allowance, as defined by ACI, is increased from 0.3mm to 0.7mm.
A. mateenbar™ is at the theoretical limit for ECR-glass reinforced rebar. Other reinforcements can be used, such as Carbon fibre, Aramid fibre or S-glass. However, all these reinforcement options are very expensive, so they are generally not practical due to the significant cost increase.
A. Whilst composite rebar itself is linear elastic to the point of failure, correct design methodology ensures the structure exhibits the desirable ductile failure mechanism.
This is achieved by a balanced reinforcement design. The higher tensile strength of the reinforcement then forces a mechanism of progressive bond-failure, which results in a ductile failure mode of the structure. This is outlined in the American Concrete Institute ACI 440 documents.
A. mateenbar™ is manufactured from a high grade glass fibre called ECR-glass which is immune to alkaline attack.
A. mateenbar™ bends must be manufactured to shape at the factory. However, standard bend shapes are available.
A. Rebar bends are not as strong as straights. It should be noted that this is also true of steel rebars.
A. When considering the design and total life issues using traditional steel reinforcing, composite rebar is cost competitive against steel. If corrosion is not an issue or non-metallic reinforcement is not required, then steel is usually a cheaper option.
Typically GFRP rebar is unfairly compared on unit costs versus steel. Savings can be made in one or more of the following ways:
A. On-site handling of composite rebars is very similar to that of steel. Most reinforcement materials are by their very nature robust, but should all be treated with some degree of care.
In this respect mateenbar™ is no different to any other reinforcement.
A. With any rebar, including steel, significant damage must be addressed. However, minor damage will not affect the performance of mateenbar™.
For example, mateenbar™ is manufactured from corrosion resistant material, and, unlike epoxy coated rebar, it does not rely on a coating to protect the rebar from the elements. Thus, minor scratching of the surface will not have a significant effect and will not cause accelerated corrosion.
A. You should design around the properties of mateenbar™. The American Concrete Institute ACI 440 committee is an excellent source of information and designers should familiarise themselves with ACI 440.1R-06 or similar guides. The Canadian Standards CSA S806 and CSA S807 are also well established and very valuable to designers.
Pultron has a support service, and can assist with or review designs, and are happy to work with design engineers to assist them in the transition from steel to mateenbar™.
A. Whenever you have to make considerations for corrosion protection of rebar or need non-metallic properties, you should consider the use of mateenbar™ instead.
The use of cathodic protection or extra allowances on concrete coverage, or special additives to ensure the concrete is waterproof are all indications that steel is not a suitable material. Protection methods do not actually solve the problem, but simply delay the inevitable outcome of corroded reinforcement.
In these cases, the use of mateenbar™ should be considered for the performance / cost benefit it will offer.
Our technical sales team would be glad to answer any further questions on the use of mateenbar™ GFRP rebar.
A. GFRP rebar and FRP rebar are usually the same product. GFRP stands for Glass Fibre Reinforced Plastic, whereas FRP stands for Fibre Reinforced Plastic, so technically encompasses other fibres such as basalt and carbon fibres. However, glass has the best strength to cost ratio of all fibres, so is the most commonly used material the composites industry. GFRP rebar is also commonly called fibreglass rebar (or fiberglass rebar for our American friends).
Durability unmatched by any steel reinforcement