ASTM D7568-23 PDF

Overview

ASTM D7568-23: Standard Specification for Polyethylene-Based Structural-Grade Plastic Lumber for Outdoor Applications establishes comprehensive requirements for plastic lumber products designed for structural use outdoors. This standard covers solid, rectangular structural-grade plastic lumber (SGPL) where polyethylene resin constitutes at least 50% of the product by weight. It applies to main and secondary framing members such as joists, beams, columns, planking, and bracing, commonly used in outdoor structures like decks, boardwalks, docks, and platforms. ASTM D7568-23 is a procurement specification aimed at ensuring material performance, dimensional consistency, durability, and safety when used in load-bearing outdoor applications.

Key Topics

• Material Composition: Specifies that SGPL products must be primarily polyethylene-based, with non cross-linked polyethylene as the continuous phase. Both virgin and recycled polyethylene are permitted. Use of cellulosic materials as additives, fillers, or reinforcements is not allowed.
• Reinforcement and Additives: Allows for various fiber reinforcements, including fiberglass, carbon, aramid, and other polymers, as well as chemical additives like colorants, ultraviolet stabilizers, and fire retardants.
• Dimensional Tolerances: Details strict tolerances for thickness, width, length, flatness, squareness, and crook to ensure consistency and compatibility with traditional lumber sizes.
• Performance Criteria: Establishes minimum requirements for stress, modulus, creep rupture, thermal expansion, weatherability, and flame spread.
• Product Identification: Each SGPL formulation (combination of resin, fillers, and additives) must be tested and evaluated as a distinct product.
• Limitations: SGPL products should not be used as tensile members or in applications requiring non-uniform reinforcement distribution.
• Testing & Quality Assurance: Requires performance verification through mechanical testing, hygrothermal cycling, and quality assurance measures as per referenced ASTM test methods.

Applications

ASTM D7568-23 is specifically applicable to outdoor structural uses where long-term performance and safety are critical. Its key applications include:

• Deck and Boardwalk Construction: SGPL products offer a durable, weather-resistant alternative to traditional wood, ensuring stability and structural integrity in moist or corrosive environments.
• Dock and Platform Framing: The specification ensures materials withstand repeated exposure to water, UV, and temperature fluctuations.
• Replacing Wood in Outdoor Structures: By providing clear guidelines for dimensional tolerances and structural properties, the standard facilitates the use of polyethylene-based lumber as a direct replacement for wood in many framing applications.
• Sustainable Construction: The allowance for recycled polyethylene aligns with environmentally responsible building practices.

The specification is valuable for manufacturers, engineers, architects, and contractors who need reliable, consistent structural-grade plastic lumber for exterior framing projects. It improves communication between buyers and sellers, ensures compliance with building codes, and supports procurement decisions by defining minimum performance and durability requirements.

Related Standards

ASTM D7568-23 references and is complemented by several related ASTM and industry standards to guide testing, terminology, and application practices:

• ASTM D6108: Compressive properties of plastic lumber and shapes
• ASTM D6109: Flexural properties of unreinforced and reinforced plastic lumber and related products
• ASTM D6112: Compressive and flexural creep and creep-rupture of plastic lumber and shapes
• ASTM D6341: Linear coefficient of thermal expansion of plastic lumber
• ASTM D6662: Specification for polyolefin-based plastic lumber decking boards
• ASTM D7032: Performance ratings for wood-plastic composite and plastic lumber deck boards and related components
• ASTM E84: Surface burning characteristics of building materials
• ASCE 7: Minimum design loads for buildings and other structures

These standards support the proper specification, testing, and use of polyethylene-based structural-grade plastic lumber in demanding outdoor environments, enhancing the reliability and safety of resilient, sustainable construction methods.

Keywords: ASTM D7568-23, polyethylene-based plastic lumber, structural-grade, outdoor applications, recycled plastics, plastic lumber specification, framing members, weather-resistant, sustainable construction, material performance.