ASTM A615 is a standard specification for Deformed and Plain Carbon-Steel Bars (also known as rebars or reinforcing bars) used for Concrete Reinforcement. It covers bars and coils of carbon steel in various shapes and sizes, intended for use in the reinforcement of concrete structures. The specification mainly includes three grades of steel:
|Steel Grade||Minimum Yield Strength in Tension|
Scope of ASTM-615
The specification covers both deformed and plain bars, with deformed bars having a pattern of ridges or grooves on the surface to improve the bond between the bar and the concrete. The bars are intended for use in the construction of buildings, bridges, and other structures where a high degree of tensile strength is required. These bars increase the load bearing capacity of concrete structures in tension as concrete is very weak in tension.
The ASTM 615 also includes requirements for the chemical composition, mechanical properties, and size and shape of the steel bars.
For the chemical composition, the specification specifies the maximum allowable amounts of various elements such as carbon, manganese, phosphorus, and sulfur.
For the mechanical properties, the specification includes requirements for the tensile strength, yield strength, and percentage elongation of the steel bars.
For the size and shape of the bars, the specification includes requirements for the diameter, weight, and length of the bars, as well as tolerances for these dimensions.
Loading Rates for Testing Rebars
According to ASTM A615, the loading rate for testing of steel rebars should be in accordance with ASTM E8/E8M, “Standard Test Methods for Tension Testing of Metallic Materials.”
ASTM E8/E8M specifies the requirements for tension testing of metallic materials, including the loading rate to be used during testing the rebars.
The loading rate is the rate at which a load is applied to the test specimen during a tension test.
The loading rate is typically expressed in units of force per unit of time or strain rate, such as pounds per minute or newtons per second or millimeter per minute.
The loading rate can be varied depending on the specific requirements of the test, the properties of the material being tested, and the type of testing equipment being used.
In general, the loading rate for tension testing of steel rebars should be sufficient to produce the desired level of accuracy and precision in the test results, while also taking into account the capabilities of the testing equipment and the mechanical properties of the steel rebars.
According to ASTM E8/E8M, “Standard Test Methods for Tension Testing of Metallic Materials,” the loading specifications for tension testing of metallic materials depend on the size of the test specimen and the type of testing equipment being used.
For test specimens with a cross-sectional area of less than or equal to 2 square inches (13 square cm), the minimum loading rate is typically 0.5 inches per minute (2.5 mm/min) or 12 inches per minute (305 mm/min).
For test specimens with a cross-sectional area greater than 2 square inches, the minimum loading rate is typically 0.2 inches per minute (1.0 mm/min) or 4 inches per minute (102 mm/min).
These minimum loading rates are intended to ensure that the test results are accurate and reliable, while also taking into account the capabilities of the testing equipment.
In addition to the minimum loading rates, ASTM E8/E8M also includes recommendations for maximum loading rates that may be used for certain types of materials or testing conditions.
For example, for test specimens made of low-carbon steel or aluminum alloys, the maximum loading rate is typically 2 inches per minute (51 mm/min).
For test specimens made of high-strength steel or other materials with high strain rates, the maximum loading rate may be higher.
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Summary of the procedure
ASTM A615 is a standard specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement, and it includes requirements for the testing of steel rebars to determine their mechanical properties, such as their tensile strength, yield strength, and elongation. The standard specifies the test methods and procedures to be used for these tests, as well as the required test equipment and the minimum acceptance criteria for the test results.
- One common method for testing the tensile strength of steel rebars as per ASTM A615 is the tension test, which involves applying a tensile force to a specimen of the rebar until it fractures.
The tensile strength of the rebar is determined by measuring the maximum load that the specimen can withstand before breaking, and dividing it by the cross-sectional area of the specimen.
The test is typically conducted in accordance with ASTM A370, “Standard Test Methods and Definitions for Mechanical Testing of Steel Products.”
- Another common method for testing the yield strength of steel rebars as per ASTM A615 is the bend test, which involves bending a specimen of the rebar until it deforms permanently.
The yield strength of the rebar is determined by measuring the maximum load that the specimen can withstand before deforming permanently and dividing it by the cross-sectional area of the specimen. The test is typically conducted in accordance with ASTM A370 or ASTM A615.
- The elongation of steel rebars as per ASTM A615 can be determined by measuring the increase in length of the rebar specimen after it has been subjected to a tensile load.
The elongation is typically measured as a percentage of the original length of the specimen. The test is typically conducted in accordance with ASTM A370 or ASTM A615.
Common Testing Machine used as per ASTM 615
A universal testing machine (UTM) is a device that is used to test the mechanical properties of materials, including tensile strength, compressive strength, and modulus of elasticity.
It applies a force to the material being tested and measures the response of the material to that force.
The test sample, in this case a steel rebar, is clamped in the machine and a load is applied to it using a hydraulic cylinder or a motor-driven screw.
The machine is able to apply a wide range of forces and can be used to test a variety of materials, including metals, plastics, and composites.
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