The American Society for Testing and Materials creates standards for building materials including pavement. ASTM C902 is the specification for brick when it is used as a paving material for low weight vehicles, bikes, and pedestrians. C902 bricks or paver stones can be hexagonal, square, or rectangular. Pavers used outdoors must be tested for their water absorption and saturation to determine how vulnerable they are to repeated freezing and thawing.
ASTM C902 bricks are approved for use in pedestrian walkways. They can also be used for residential driveways and commercial driveways that see little traffic and no heavy vehicles. ASTM C902 class SX and MX stone bricks can also be used for outdoor patios. The material standards for ASTM C902 pavers are the same whether the brick is glazed or not. Type I are approved for heavy traffic. Type II pavers are intended for intermediate traffic. Type III are used in low traffic areas.
Classes of C902 Paver Stones
Class SX is rated for severe weathering. MX is rated for moderate weathering. Class NX cannot withstand weathering or exposure to rain and cold, so it is only to be used inside buildings. Material specifications for different classes of brick vary on its application. According to "Masonry Design and Detailing" by Christine Beall, "compressive strength and cold water absorption for class SX molded brick are one half that of extruded brick at 4000 psi and 16%, respectively."
Class SX stones must have a minimum compressive strength of 7,000 pounds per square inch. If an average across a five brick sample is taken, the average of all five paver stones must be 8,000 pounds per square inch. Class MX and NX stones must have a minimum compressive strength of 2,000 pounds per square inch.
Class SX brick cannot absorb more than 11 percent of the cold water it is exposed to, while class MX brick cannot absorb more than 17 percent of the water it is exposed to. Cold water absorption requirements are lower if a five brick sample is used. Because class NX pavers are to be used indoors, this class doesn't have a water absorption standard.
The saturation coefficient is the ratio of water weight absorbed by a brick when it is immersed in cold water. Class SX brick has a maximum saturation coefficient of 0.80. Class NX stones and bricks do not have to meet a specific saturation standard.
Bricks can be tested individually or in groups of five to determine if the paver stones meet C902 standards. When five stones are tested for compressive strength, the average compressive strength they must meet is higher than if a single stone is tested. If the sampled five bricks survives 15 cycles of the sulfate soundness test, water absorption and saturation testing is not required.
- "Sustainable Industrial Design and Waste Management"; Salah el- Haggar; 2007
- "Masonry Design and Detailing"; Christine Beall; 2003
- "Concrete and Masonry Databook"; Christine Beall, Rochelle Jaffe; 2002
- "Architectural Graphic Standards for Residential Construction"; Charles George Ramsey; 2003
- "Masonry: Opportunities for the 21st Century"; Diane Throop, R. E. Klingner; 2002
- ASTM C902 - 10e1 Standard Specification for Pedestrian and Light Traffic Paving Brick; ASTM
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