Effectiveness of vertical moisture barriers in highway pavements on expansive soils /
Moisture fluctuations in expansive clay subgrades in response to rainfall and evapotranspiration cause volume changes that in turn cause excessive damage to pavements resting on such subgrades. The Texas Department of Transportation is installing vertical moisture barriers on pavements in order to...
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| Format: | Thesis eBook |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1993.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Summary: | Moisture fluctuations in expansive clay subgrades in response to rainfall and evapotranspiration cause volume changes that in turn cause excessive damage to pavements resting on such subgrades. The Texas Department of Transportation is installing vertical moisture barriers on pavements in order to stabilize the moisture condition under the pavements and thus reduce the development of roughness on these pavements. A total of eleven pavement sections in three of the seven climatic zones in Texas were chosen for this study in order to study the effectiveness of vertical moisture barriers in controlling the development of roughness. The moisture condition (suction) in the subgrade soils was measured using either thermal moisture sensors or thermocouple psychrometers. In addition, the surface profiles of the pavements were measured with the GM profilometer. Samples of the soil were taken and laboratory tests of the Atterberg limits, grain size distribution and suction vs. water content relations were made. A finite element program, FLODEF, which couples moisture flow and elasticity was calibrated to reproduce the field observations of the suction in each of the locations. The program was then used to perform a study of the effects of climatic zone, degree of cracking in the soil, depth of the moisture barrier, and lateral drainage condition on the rate of increase of pavement roughness. The program shows the conditions under which moisture barriers will be effective and other conditions in which moisture barriers will have little effect. Sites in wet and semi-arid climates, with medium cracked clay soils show the greatest benefit from using vertical moisture barriers. |
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| Item Description: | "Major Subject: Civil Engineering". Vita. |
| Physical Description: | xx, 196 leaves : illustrations ; 28 cm. Also available online. |
| Bibliography: | Includes bibliographical references. |