ASTM A955/A955M - Standard Specification for Deformed and Plain Stainless Steel Bars for Concrete Reinforcement
Title: Understanding ASTM A955/A 955M - Stainless Steel Bars for Concrete Reinforcement
Introduction
In the vast world of construction, the use of reinforced concrete is a common practice. One crucial component of reinforced concrete is the reinforcing bar, often made of stainless steel for its enhanced corrosion resistance and controlled magnetic permeability. This article delves into the details of the ASTM A955/A 955M standard, guiding the manufacture and use of deformed and plain stainless steel bars employed in concrete reinforcement.
Key Features of the Standard
The ASTM A955/A 955M is a standard issued to regulate the specifications of stainless steel bars, ensuring their quality, durability, and efficiency in various applications. These bars come in three minimum yield levels: 40,000 psi, 60,000 psi, and 75,000 psi, termed as Grade 40, Grade 60, and Grade 75 respectively.
Welding these stainless steel compositions generally poses no challenges. However, it’s essential to consider pre and post-weld procedures to maintain the structural integrity and intended use of the material.
Supplementary Requirement
A supplementary requirement, marked as S1, is optional and is applicable when specified by the purchaser. This stipulation is mainly invoked to achieve a product with controlled magnetic permeability. This property is paramount in certain specialized applications where magnetic interference needs to be minimized.
Chemical Composition
The chemical makeup of the stainless steel alloy is a pivotal consideration. A cooperative decision between the manufacturer and purchaser, considering the specific application and environment where it will be used, determines the alloy’s composition. The alloys listed in Table 2 of the standard are among the most commonly used in North America. However, the selection isn’t limited to these options.
Deformations and Measurements
The standard stipulates specific requirements for the deformations on the steel bars. These deformations, or the protrusions on the bars, play a vital role in anchoring the bars within the concrete. The standard specifies their spacing, height, and gap to ensure optimum performance in reinforced concrete structures.
Testing and Inspection
Every batch of steel bars produced under this standard undergoes rigorous testing to ascertain their tensile strength, bendability, and other physical properties. Inspection protocols are well laid out to ensure that the bars meet the stipulated requirements before they are deemed fit for the market.
Corrosion Resistance
Given that these bars are often used in environments that could predispose them to corrosion, the ASTM A955/A 955M standard mandates corrosion resistance testing. The austenitic stainless steels, for instance, are tested according to Practice E of Specification A262.
Conclusion
The ASTM A955/A 955M standard is a comprehensive guide that ensures the production and use of high-quality stainless steel bars for concrete reinforcement. Every stakeholder in the construction industry, from engineers and architects to contractors, must be acquainted with this standard to ensure the structural integrity, durability, and safety of reinforced concrete structures. By adhering to this standard, manufacturers are not just meeting legal requirements but are also contributing to the advancement of safe and sustainable construction practices globally.
Note
The standard is subjected to revisions, and as such, it’s essential for professionals in the field to stay updated with the latest editions to ensure compliance with the current requirements and recommendations.