We are in the process of monitoring the installation of approximately one mile of 18" Reinforced Concrete Pipe for storm drain purposes along a major road improvement project. The pipe will have 5 feet to 10 feet of cover. The contractor originally intended to use a one-half sack or better cement/ABC slurry from the trench bottom to one foot above the top of pipe. The contractor has asked us to consider allowing the use of 'chips' from top of bedding to one foot above the top of pipe. Density tests would be taken at springline. The source of the chips is a concrete aggregate supplier's 'reject' pile, and as such consists of clean, durable aggregate with approximately 90 % fractured faces. Several gradations are available, ranging from # 8 grading (ASTM C-33) to finer than # 8 grading. The finer material is preferred by the contractor, and it would be 100% passing 1/4" sieve, 40% passing the #8 sieve, 5% passing the #30 sieve, and virtually no -#200 material (1 or 2%). The American Concrete Pipe Association has been completely unresponsive, and of no help. Anyone with knowledge of, or experience with, this type of situation, I would truly appreciate some advice
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