CONCRETE PIPE Design Methods There are essentially two design methods to select from when specifying concrete pipe: • ASTM C76 Class Design • ASTM C1417 Standard Installation and Design (SIDD) The following sections provide a brief overview of each design method, including the benefits and drawbacks associated with each. ASTM C76 Class Design This design method is based upon the ASTM C76, which provides a standardized classification system for concrete pipe based on the D-Load (three-edge bearing) test relative to the 0.01 inch crack and ultimate loading values. These pipe classifications include: • • • • Class II (50D) Class III (65D) Class IV (100D) Class V (140D) CONCRETE PIPE DESIGN MANUAL The benefit to the class system is that it provides a convenient, consistent method to pipe strength selection. For added convenience, there are pipe class estimation tables available (pg 37) from most manufacturers that list the different classes of pipe available and the maximum allowable earthen cover as it relates to installation type (pg 36). These pipe class estimation tables may vary depending on the specifications of local municipalities. From a manufacturer perspective, the class system also has the advantage of allowing the opportunity to stock pipe materials and thereby provide cost savings to the consumer versus customized design. In some scenarios, the class system has the disadvantage of providing more reinforcement than is necessary for a given cover. However, should project conditions change or additional fill is considered in the future (i.e. as the result of road realignment), the class system provides more flexibility in terms of pipe re-use than does SIDD pipe. PAGE 26 LAFARGE PIPE eMANUAL