23 April 2010
23 April 2010
The new standard, ASTM D7565/D7565M, Test Method for Determining Tensile Properties of Fiber Reinforced Polymer Matrix Composites Used for Strengthening of Civil Structures, provides tensile strength and modulus of elasticity, which are key parameters used in the design of a strengthening application.
Subcommittee D30.05 on Structural Test Methods has been developing a series of standards addressing polymer reinforced composite materials used in the repair and reinforcement of concrete buildings and other civil structures. The latest approved standard in this series addresses the tension testing of materials that are externally bonded to concrete and other structural materials for repair, retrofit and strengthening purposes.
Subcommittee D30.05 is part of ASTM International Committee D30 on Composite Materials.
Russell Gentry, D30 member and associate professor at Georgia Tech, says that the new standard differs from the most well-known tension testing standard for composites — ASTM D3039, Test Method for Tensile Properties of Polymer Matrix Composite Materials — in that it provides specific instructions on fabricating specimens and calculating test results in a manner used in the construction industry as these materials are applied and cure in the field, and not in the controlled conditions typical of aerospace applications.
According to Gentry, material suppliers, contractors who are applying composite materials and quality control laboratories will be the primary users of ASTM D7565. Three other D30.05 civil infrastructure standards addressing material properties and durability of composite concrete reinforcement are currently under ballot. These proposed standards are:
ASTM WK22346, Test Method for Determining Overlap Splice Tensile Properties of Fiber-Reinforced Polymer Matrix Composites Used for Strengthening of Civil Structures;
ASTM WK22348, Test Method for Transverse Shear Strength of Fiber-Reinforced Polymer Matrix Composite Bars; and
ASTM WK27200, Test Method for Alkali Resistance of Fiber-Reinforced Polymer (FRP) Matrix Composite Bars Used in Concrete Construction.
Gentry notes that much of this standards development work has been done in conjunction with American Concrete Institute (ACI) Committee 440 on Fiber Reinforced Polymer Reinforcement.
“We are in our fifth year of an ASTM-ACI collaboration that has produced five test methods so far,” says Gentry, who also notes that greater participation in D30.05 activities is encouraged. “Many of these proposed test methods would benefit from additional review from the civil engineering structures community, and from round robin testing to establish precision and bias.”
Toho Tenax is introducing a high-tensile, highly shock-resistant prepreg that incorporates carbon fibre developed for aerospace applications and carbon nanotubes (CNTs).
Thai Flight Training (TFT), a subsidiary of Thai Airways, recently ordered an Airbus A320 door trainer from Spatial Composite Solutions.
NTPT is collaborating with the Ecole polytechnique fédérale de Lausanne - Swiss Centre of Technology (EPFL) and other partners to research discontinuous fibre composite tubes for high performance applications.