Graduation Semester and Year

2008

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Department

Civil Engineering

First Advisor

Anand Puppala

Abstract

Pavement cracking is one of the major maintenance works that requires millions of dollars in repair costs annually. Pavement cracks are formed due to moisture and temperature fluctuations in the soil. Stabilization of pavement shoulder subsoil with the addition of compost material was studied for preventing pavement cracks. Eight different compost materials with three major feed stock sources such as biosolids, wood waste, and animal manure were investigated in this research. Compost treatment studies were performed at four different test sites located in various regions of the state of Texas. Laboratory experiments were conducted completed compost manufactured topsoil's (CMTs) to determine their physical and compaction characteristics as well as engineering properties such as linear shrinkage and free swell properties. Test sections were prepared with CMTs as shoulder covers and these sections were instrumented with temperature and moisture probes underneath the CMT cover. Elevation surveys and digital images of the CMTs and the adjacent pavement sections respectively were periodically obtained. Statistical analyses were performed on the maximum monthly moisture and temperature variations of CMTs and Control section were conducted. Elevation survey data and the digital images of the sites were collected and analyzed to determine soil erosion loss and magnitude of pavement cracking, respectively. Overall, it was concluded that both biosolids and wood based composts were effective; while the manure based compost was not effective in mitigating pavement cracking. These findings were based on moisture variation, elevation survey, and digital image analyses. Surface soil samples were collected from the CMTs and laboratory experiments such as organic content (OC), cation exchange capacity (CEC), and total soil suction studies were performed at various time periods. Three kinds of models were analyzed for simulating the degradation of the soil properties with time and it was found that the measured data fitted well when an exponential decay model was used. The equations developed from these models were used to determine the service life of the compost treatment. The average of the service life predicted based on the OC, CEC and total soil suction results was taken as the service life of the compost treatment. The service life of the biosolids and wood based compost was 5 to 6 years while the manure based compost had a service life of 4 to 5 years. Cost analysis was performed in order to compare cost effectiveness between CMTs, seal coating, and crack sealing. It was concluded that CMTs were recommended over seal coat and crack sealing maintenance techniques based on the costs, quality control issues and benefits of compost treatment in promoting environmental recycling efforts. Future research needs in this area are also summarized.

Disciplines

Civil and Environmental Engineering | Civil Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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