2014 Updates to ASTM C12

Abstract

The American Society for Testing and Materials (ASTM) standard C12 “Standard Practice for Installing Vitrified Clay Pipe Lines” gives recommended methods for installing vitrified clay pipe (VCP). C12 was significantly modified for the 2014 version (C12-14). Three of the most notable changes were: (1) Use of uncompacted soil for the bedding (2) Adoption of uniform soil groups (3) Recommended gradation for the bedding soil. The current standard includes several bedding classes for proper support of the pipe with corresponding Load Factors. The Load Factors reflect the amount of support the bedding soil gives to the installation. While the basic trench configurations and Load Factors have not changed, the 2014 version incorporates various improvements including: (1) Discontinuation of the concrete arch bedding class (2) Adoption of Uniform Soil Groups for Pipe Installation (3) Recommendation for methods of improving the foundation to provide proper support for the pipe when the foundation is deemed not suitable (4) Updates to bedding standards, including: (1) Use of uncompacted soil for the bedding (2) Recommended gradation for bedding soils (3) Specifying the appropriate amounts of fractured faces for Class II soil particles (4) Limiting the maximum soil particle size for bedding and initial backfill materials to 1-inch and 1½-inch particles. (1) Requiring shovel slicing of haunch area soil to occur before the bedding height is 0.25 of the outside diameter of the pipe. (2) Replacing subjective language with more definitive language (3) ASTM specialized standards relating specifically to Controlled Low Strength Materials (CLSM) bedding for VCP. In 1995, C12 became the first pipe installation standard to give CLSM bedding as a viable option. Requirements for flowability when placed, 28 day compressive strength, and set time prior to backfill load are now referenced to the ASTM CLSM standards. One advantage of using VCP is that it will not float during CLSM installation.