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Title:An investigation into the effect of waterblast on concrete and asphalt surfaces
Author(s):Maiga, Nanaissa
Advisor(s):Lange, David
Department / Program:Civil & Environmental Eng
Discipline:Civil Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Rubber removal, Grooves, Airport Runway Friction
Abstract:Runway surface condition is critical to airport safety. Grooved runways are a standard feature because they permit drainage, allowing for safer landings by reducing the risk of hydroplaning. Hydroplaning occurs when water is pooling at the surface of the runway reducing severely the friction which dangerously increases airplane braking distance. When a large aircraft lands, approximately 1.4 pounds of rubber per tire is deposited onto the runway. This is due to the friction produced by the locked wheels during landings: they generate excess heat and pressure that debonds the rubber from the tire. As more aircraft land on the runway, more rubber accumulates and decrease the runway’s coefficient of friction. Once this occurs, water blasting is most commonly used at O’Hare International Airport to remove the excess rubber. The main drawback to this method is that there is a risk of eroding the concrete surface so much that grooves fail to provide a path for water to escape. Damage is defined as the grooves not being able to perform as a path for water to escape. The effects of waterblast on concrete after rubber removal are equivocal. This study developed a quantitative method to analyze concrete and asphalt surfaces. The results were used to provide recommendations to achieve satisfactory rubber removal without erosion of the airport runway. The quantitative analysis was done using a picture-generated point cloud using an incremental reconstruction algorithm. Both concrete and runway surface features were considered in this study. The tests were performed in a laboratory, and waterblast equipment available limited the maximum water velocity to 412m/s. It was found that concrete surfaces could not be damaged at the maximum velocity tested. Based on literature and experimental evidence, this study recommends a maximum pressure of 15,000 psi for rubber removal on concrete surfaces. Concrete runways showed a roughening of the surface after testing which may have manifested as an improved friction. However, there was slight flushing observed on asphalt samples with soft binders under the least abrasive testing condition of 162 m/s with the nozzle inclined at 90 degrees. The flushing of the asphalt is unsafe because it can lead to loss of pavement strength as well as macrotexture. This study recommends greater vigilance when dealing with asphalt surfaces and hydrocleaning at lower pressures than used for concrete. Also due to the asphalt binder properties, hydrocleaning settings should differ with temperature. Finally, it was recommended to reproduce the tests on a bigger scale on runway surfaces and validate the results of the analytical tool developed with laser profilometry.
Issue Date:2019-05-29
Rights Information:Copyright 2019 Nanaissa Maiga
Date Available in IDEALS:2019-11-26
Date Deposited:2019-08

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