National Concrete Pipe
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National Concrete Pipeational Concrete Pipe Company tests performs materials tests on a daily basis. These daily tests involve visual checks, compressive cylinder tests, slump tests. Weekly tests include the 3-edge bearing test witnessed by a IDOT representative. Other tests, such as hydrostatic, 2-Z, and vacuum tests, are preformed on a job by job basis per specification.

Vacuum Testing

    Vacuum testing is a process where a piece of pipe or line of pipe to be tested is plugged on either end.The air is then removed from the plugged line by a vacuum pump or vacuum reservoir. the amount of loss is used to determine the acceptability of the piece of pipe, or the line of pipe. The method designation is ASTM C-1214-94. This procedure is required for sanitary sewer lines and any other lines where exfiltration and infiltration are concerns.

Hydro-static Testing

Hydro-static testing of concrete pipe and joints is a quality control test preformed to establish that the pipe meets the requirements stated in the specifications for the installed wall, the joint, or both. The test complies with specification ASTM C-497. The pipe is blocked on either end, the pipe is then filled with water, air pressure is applied to specific amounts and held for a particular length of time without additional air. Over the specified time period the pipe and joint is watched for leakage from the wall or the joint and must meet specification criteria.

Hydro-static testing of pipe and joints under the specification of 2-Z is of concern to the manufacturer of concrete pipe sold to the Water Reclamation District for the Greater Chicagoland Area. This 2-z applies only to them. The test is similar to the test of ASTM C-497, but ASTM C-361 comes into play also when agency asks for the test to be performed at 120% of the specified internal working pressure for 20 minutes with no visible signs of leakage from the wall or the joints. This all has to be performed with the agencies' own requirement of 2-Z. As an example, testing a 60" pipe means that two 60's need to be joint separated by 1.75" and then tested. The manufacturer is required to submit their joint drawings to the agency for approval of dimension before their pipe will be considered for usage.

3-Edge Bearing Test

This test is required of IDOT and is performed each week at the National Concrete Pipe facility. The test complies with the ASTM C-76 standard for D-loads. Concrete pipe is placed on a rack and squeezed until it shows a 1/100th inch crack and then squeezed more until it fails. Notations are made as to what strengths are achieved. Each size and class of pipe has its own parameters it needs to meet.

Slump Test

The purpose of the slump test is to determine the consistency of the concrete and complies with ASTM C-143.  National Concrete Pipe Company uses this test for its products manufactured with the wet-cast method, as it pertains to the specification of the particular project.


Contact Information

National Concrete Pipe Company is in operation from 5am until 5pm, 5 days per week. National Concrete Pipe Company can be reached via E-mail, web site, and Fax 24 hours a day.

National Concrete Pipe Company
11825 Franklin Park,
Franklin Park, IL  60131
phone: 630-766-3600

fax: 630-766-6197
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