CIGMAT Report 2013

By C. Vipulanadan, PhD, P.E., professor and director of Center for Innovative Grouting Materials and Technology (CIGMAT) and Texas Hurricane Center for Innovative Technology (THC-IT), Department of Civil and Environmental Engineering, University of Houston | October 2013, Vol. 68 No. 10
Figure 1. Piezo-resistive behavior of modified oil well cement

In order to quantify the infiltration at various types of pipe-joints, a unified testing program was developed to test 30-inch diameter sewer pipe-joint up to a hydrostatic pressure of 7 psi. A testing protocol was developed and approved by a steering committee with representation from the EPA, pipe associations, cities and consulting engineers. The testing protocol outlined the procedures to determine the leakage rates at pipe-joints under shear loading and angular deflection. A testing facility was designed and constructed in the CIGMAT laboratory to perform the pipe joint tests in duplicate.

In this study, two types of polypropylene (PP) pipes (triple wall and double wall) were tested. A total of four 30-inch diameter PP pipe joints were tested. During the straight test (unloaded joint), the joint was subjected to hydrostatic pressure incrementally to a maximum hydrostatic pressure of 7 psi with a total testing time of 30 minutes and there was no water leak in the joints. During the shear test, the joint was subjected to incremental shear loading. The maximum shear forces that were applied to the joints varied from 2,268 pounds to 2,899 pounds. The total shear testing time was 2.5 hours and the joint was subjected to a maximum hydrostatic pressure of 7 psi at every increment of shear load and there was no water leak in the four joints tested.

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Figure 4. Angular deflection test on triple wall polypropylene pipe joint

During the angular test, the joint was subjected to angular in steps of 0.5 degrees to a maximum rotation of 2 degrees at the joint. The total testing time was two hours for each pipe joint and the joint was subjected to a maximum hydrostatic pressure of 7 psi and the maximum shear load at the joint varied from 292 to 533 pounds during the angular test. There was no water leak in the four joints tested in this study.