Modern Construction Materials
Standards Promote Advances in Construction Technologies
For virtually any product, standards are a critical step along the way from research and development to adoption in the marketplace. Without standardization to streamline production processes, ensure quality and safety and provide benchmarks for regulators, the marketplace and public acceptance of new products would be difficult to achieve. Many industries today are faced not only with managing the march of technological development, but with pressures to do so efficiently, cost-effectively and with public and environmental safety in mind. The construction industry is no exception.
The appearance, component materials, energy efficiency and environmental impact of habitable structures has changed dramatically over recent years due in large part to the successful standardization of new materials, processes and technologies. This article provides a sampling of some more recently developed construction technologies and shows where ASTM International’s technical committees have provided needed standards that have swept new construction technologies off the drawing board and into our built environment.
A Building’s Skin
Exterior insulation and finish systems were first used after World War II in Germany to resurface buildings damaged by the ravages of that conflict; since the 1960s, their use has become widespread. EIFS are lightweight, multi-layer barrier systems that help keep moisture from outer walls. With several components, from panels of foam insulation fastened to a substrate and a base coat, to a reinforcing mesh and finishing coat, EIFS are complex systems with materials that have to successfully connect for years in order to keep moisture at bay. Standards are critical for all components to ensure proper interaction and long life.
Developing standards for EIFS has been a key activity of ASTM International Committee E06 on Performance of Buildings since the 1990s. Subcommittee E06.58 on Exterior Insulation and Finish Systems published its first EIFS standard, E 2098, Test Method for Determining Tensile Breaking Strength of Glass Fiber Reinforcing Mesh for Use in Class PB Exterior Insulation and Finish Systems, After Exposure to a Sodium Hydroxide Solution, in 2000. Since the meshes component of EIFS are embedded into base coats containing portland cement, they may be weakened by the alkali action. E 2098 helps laboratories comparatively evaluate the alkali resistance of EIFS glass fiber reinforcing meshes.
Since that standard’s development, Subcommittee E06.58 has followed up with several more test methods and specifications that help users evaluate and specify the quality and efficiency of these systems. The subcommittee also has 10 more standards in the pipeline.
Stone Masonry Veneer
The cost savings and design freedom offered by stone masonry veneer products have led to their increased use in architectural projects. In fact, sales of manufactured stone, specifically, are expected to reach $900 million by 2009. Compared to natural stone, manufactured stone veneers can be reinforced with steel, can be precisely colored, and have a predictable, durable life. The manufactured product’s consistency of appearance makes repetitive use of the material as a trim or ornament economically feasible. In addition, older structures can be rehabilitated with manufactured stone veneer that replicates the appearance of deteriorating stone.
Recently, ASTM International’s Committee C15 on Manufactured Masonry Units formed Subcommittee C15.11 on Adhered Manufactured Stone Masonry Veneer in response to the industry’s need for standardized practices and testing. The group is currently working on a specification for this material, a practice for its installation and a test method for determining the drainage efficiency of a wall system with a scratch coat of mortar.
Structural glazing is a technology in which glass is attached to a building using sealant adhesives. Although it first appeared into the 1960s, structural glazing has, in the last 20 years, experienced exponential growth; it is now a familiar sight in high-rises and other buildings in cities all over the world.
ASTM International has had a hand in the research in and standardization of structural sealant glazing for 30 years. Committee C24 on Building Seals and Sealants has developed 12 standards for this material. These include specifications, guides and testing methodologies for such critical features as making sure a sealant is compatible with accessories in a glazing system, determining the tensile adhesion properties of a sealant and more. Since one of the main concerns about structural glazing in its early days was of course due to the fact that enormous glass panels were hanging from buildings by 12 mm beads of adhesive, standards such as these were, and continue to be, crucial to allowing marketplace and public acceptance of the technology.
ASTM has recently brought together these 12 standards along with research papers dating back to 1977 in the compilation ASTM Standards and Technical Articles Relating to Structural Glazing.
Since the early 1990s, wood-plastic composites — made from recycled wood and plastic waste — have been used as economical and environmentally friendly alternatives for decks; components such as railings, cladding, siding, molding and trim, window and door frames; and small structures such as park benches.
The involvement of ASTM International technical committees in developing standards related to wood-plastic composites began in the 1990s when ASTM Committee D20 on Plastics stepped up to fill the need for the standardization of what was at the time an emerging technology. At that time, research showed that existing standards for testing plastic materials were not adequate for the nonhomogeneous nature of plastic lumber. Committee D20’s suite of standards for wood-plastic composite materials includes:
• D 6108, Test Method for Compressive Properties of Plastic Lumber and Shapes;
• D 6109, Test Methods for Flexural Properties of Unreinforced and Reinforced Plastic Lumber and Related Products;
• D 6111, Test Method for Bulk Density and Specific Gravity of Plastic Lumber and Shapes by Displacement;
• D 6112, Test Methods for Compressive and Flexural Creep and Creep-Rupture of Plastic Lumber and Shapes;
• D 6117, Test Methods for Mechanical Fasteners In Plastic Lumber and Shapes;
• D 6341, Test Method for Determination of the Linear Coefficient of Thermal Expansion of Plastic Lumber and Plastic Lumber Shapes Between -30 and 140°F (-34.4 and 60°C);
• D 6435, Test Method for Shear Properties of Plastic Lumber and Plastic Lumber Shapes; and
• D 6662, Specification for Polyolefin-Based Plastic Lumber Decking Boards.
More recently, Committee D07 on Wood has developed two standards related to wood-plastic composites:
• D 7031, Guide for Evaluating Mechanical and Physical Properties of Wood-Plastic Composite Products; and
• D 7032, Specification for Establishing Performance Ratings for Wood-Plastic Composite Deck Boards and Guardrail Systems (Guards or Handrails).
The second of these standards provides procedures to establish performance ratings for wood-plastic composite products as a basis of code recognition and is referenced in the International Code Council Evaluation Services Acceptance Criteria 174.
Advancements in Concrete
Concrete, which has been used for millennia in some form for structures and roadways, is developing in ways that make its use easier, less expensive, safer, more varied and even more environmentally friendly.
For example, self-consolidating concrete, a type that flows into forms with no mechanical compaction required, was proposed in theory in the late 1980s by a Japanese scientist. Since then the technology has become viable and is being used in infrastructure projects around the world. The properties of SCC are achieved by using high-range-water-reducing admixtures, increasing the total quantity of fines and/or using admixtures that modify its viscosity in its plastic state. This type of concrete has numerous benefits and has expanded the role of concrete in architecture because it can be used in shapes and places conventional concrete cannot.
Without standardized testing, self-consolidating concrete could not be effectively manufactured or even used in the field. As with all types of concrete, in-situ testing is of paramount importance to ensure the integrity of the structure being built. ASTM International Committee C09 on Concrete and Concrete Aggregates has responded to the need for standards with several written specifically for this material, including:
• C 1610/C 1610M, Test Method for Static Segregation of Self-Consolidating Concrete Using Column Technique;
• C 1611/C 1611M, Test Method for Slump Flow of Self-Consolidating Concrete; and
• C 1621/C 1621M, Test Method for Passing Ability of Self-Consolidating Concrete by J-Ring.
In addition to these documents, more are in the balloting process, including standards for coarse aggregate segregation and stability as well as a terminology standard that will define terms related to self-consolidating concrete.
Another relatively new form of concrete is pervious concrete, which permits rainwater to percolate to underlying soil. This material promises to help the natural environment in an increasingly paved world by encouraging the normal flow of stormwater and alleviating flooding. The use of pervious concrete by municipalities and businesses is on the rise, particularly since the U.S. Environmental Protection Agency has recognized its use as a best-management practice for stormwater management.
ASTM Committee C09 has formed two task groups on preparing pervious concrete specimens and research within its Subcommittee C09.49 on Pervious Concrete. One group is evaluating an international array of test methods being considered by agencies and researchers in order to determine which tests might be incorporated into ASTM International standards. The second group is developing a consolidation technique.
The members of ASTM International’s technical committees are on the front lines of new technology and bring with them from their experience in government, academia and industry the keys to creating the standards that effectively introduce materials like these to the marketplace. For more information on any of these activities or to participate in ASTM standards development, visit the ASTM International Web site. //