16_DESIGN 01: Estimating Service Life for Steel Pipe in Non-Abrasive Environments

Introduction: Culverts are typically used to divert water from gathering onto roadways by allowing the runoff to flow beneath the street surface. These pipe-like structures are buried underneath roadways and are in contact with the surrounding soil. Particularly, corrugated steel pipe (CSP) culverts are the subject of this study. Problem: An immediate engineering problem that transportation departments are faced with is the longevity of CSPs. This issue of service life is largely dictated by the loss of wall section of pipe arising from the phenomenon of corrosion due to chemical and electrochemical processes based on two major factors: pH levels, or how alkaline/acidic the media is, and the resistivity of the soil, i.e. its ability to conduct electrical current indicating the presence and degree of salt concentration that can accelerate corrosion processes. Research Approach: The state of California will be split into thirds, i.e. northern, mid, and southern regions. Since the CSUN research team consists of three professors, each will have a team of two students who will accompany the faculty member to one of the aforementioned regions on three separate weekends per month during the months of April 15 - October 15 each year when the field work is scheduled to occur. The anticipated number of culverts to investigate per team per field-outing is expected to be around eight (8). The timeframe for conducting field investigations has been determined to run from April 15 - October 15 each year, to keep team members safe from any potential hazards arising from possible flooding during the rainy seasons. The estimated number of culverts to be studied will be approximately 7 months at 8 per team per month, translating to approximately 170 culverts per year and over 500 culverts for the scheduled three-year research effort. Anticipated Research Results and Benefits of Research: Based on field investigations, measurements, and analysis of the collected data, the effects of the pH and resistivity parameters on the corrosion rate of CSPs will be investigated and these will be used to improve upon the existing Caltrans service life prediction equation for CSPs.