Graduation Semester and Year

2020

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Department

Civil Engineering

First Advisor

Himan Jalali Hojat

Second Advisor

Ali Abolmaali

Abstract

Performance of reinforced concrete pipes, as a major part of the water and waste-water infrastructure, plays an important role in the resilience and sustainability of today’s modern cities. Cracks may appear in these pipes due to handling and placement and might affect their long-term performance due to corrosion concerns. Current practice for quality control after installation of these pipes is quite strict and any pipe with a crack width of more than 0.01" is not approved. The goal of this research project is to evaluate the performance of cracked reinforced concrete pipes subjected to saline environments with three different concentration of sodium chloride. The reinforced concrete pipes in this study are cracked to keep the cracks open to 0.05". The evaluation is based on strength degradation for the pipes and tension coupons, weight loss in steel specimens and elemental analysis of steel and concrete. To this end, 102 reinforced concrete pipes (RCP), each 2 ft long with an inside diameter of 24" and 3" wall thickness, are tested to find their respective D-load; among the 102 RCPs, twelve were tested as control specimens, while the remaining 81 were considered for the main tests with 9 additional ones as spare specimens. The research project consists of two phases: pre-immersion and post-immersion. In the pre-immersion phase, 90 RCPs were cracked, and spacers were inserted in the crack to keep the cracks open to 0.05". For post-immersion phase, the cracked RCPs were immersed in sodium chloride solutions with concentrations of 200, 2000 and 30000 part per million (ppm). The RCPs in the 200 and 2000 ppm solutions are tested on a bi-monthly basis while the pipes in the 30000 ppm solutions are tested monthly. For each solution, three specimens are tested. In addition to the RCPs, steel specimens were used to monitor the weight loss over time as well as strength reduction in tension test. Scanning Electron Microscope and Energy-dispersive X-ray (SEM/EDX) was also used to study the elemental analysis on the surfaces of the corroded steel and degraded concrete specimens, as well as to take more precise readings for the diameter change of the steel specimens.

Keywords

Corrosion, Reinforced concrete pipes, D-load test

Disciplines

Civil and Environmental Engineering | Civil Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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