Sodium Chloride

D 632: Standard Specification for Sodium Chloride

The performance and longevity of critical infrastructure, from roadways to construction projects, often hinge on the precise quality of the materials used. For engineers and procurement specialists, ensuring the reliability of essential chemical inputs is paramount. ASTM D 632 provides the authoritative benchmark for sodium chloride, establishing the essential quality parameters for its diverse industrial applications, making it an indispensable document for professionals involved in materials selection and quality assurance.

What is D 632?

ASTM D 632, "Standard Specification for Sodium Chloride," is an industry-leading standard developed by ASTM International. It defines the chemical and physical properties that sodium chloride must meet for use in specific engineering and construction applications, primarily as a deicing agent and for road stabilization. Its origin lies in the need for a consistent, reliable source of sodium chloride that ensures predictable performance in demanding environmental conditions.

Scope & Purpose

This comprehensive standard governs the procurement and quality control of sodium chloride intended for use as a pavement deicer and in road construction or maintenance activities. It specifies requirements for chemical composition, particle size distribution (grading), and the material's condition upon delivery. While it details requirements for two main types and grades of sodium chloride, it does not cover specialized industrial or food-grade applications, nor does it prescribe specific application methods or performance criteria beyond material quality.

Who Must Comply?

• • Primary audience: Materials Engineers, Civil Engineers, Road Maintenance Supervisors, Quality Control Inspectors, and Purchasing Agents.
• • Industries affected: Construction, Public Works, Chemical Manufacturing, Transportation, and entities involved in winter road maintenance.
• • Compliance nature: Typically voluntary, but often mandated by project specifications, procurement contracts, and regulatory bodies for public works and transportation projects.
• • Enforcement: Compliance is generally verified through laboratory testing of supplied materials, often overseen by purchasers, quality assurance departments, or third-party inspectors.

Key Requirements Overview

ASTM D 632 outlines several critical requirements to ensure the suitability of sodium chloride for its intended uses:

• • The standard requires a minimum chemical purity for sodium chloride, typically set at 95.0% NaCl by mass for deicing and road construction types.
• • Professionals must ensure that the grading (particle size distribution) of Type I sodium chloride adheres to specified sieve size requirements for optimal deicing performance and aggregate stabilization.
• • Key provisions include the definition of two distinct grades for Type I sodium chloride, catering to different regional preferences and application efficiencies.
• • The specification mandates that the sodium chloride must arrive in a free-flowing and usable condition, free from excessive caking or foreign matter.
• • It also details sampling procedures and acceptable tolerances for variations in chemical composition and grading for materials delivered to a purchaser.

Related Standards & References

ASTM D 632 works in conjunction with other proven ASTM standards to ensure comprehensive material quality. Test Method C 136 is essential for determining the grading and particle size distribution of aggregates, including sodium chloride. Practice E 29 provides guidance on rounding test data for conformance, ensuring consistency in reporting results. Furthermore, Test Methods E 534 offers a referee method for the chemical analysis of sodium chloride, providing a definitive benchmark for dispute resolution.