Effectiveness of Controlling Pavement Roughness Due to Expansive Clays with Vertical Moisture Barriers

Details

• Creators:
  Jayatilaka, Ranasinghege ; Gay, Derek A ; Lytton, Robert L. ; Wray, W Kent
• Corporate Creators:
  Texas Transportation Institute. Texas A&M University
• Corporate Contributors:
  Texas Department of Transportation ; United States. Department of Transportation. Federal Highway Administration
• Subject/TRT Terms:
  Atterberg Limits Climate Expansive Clays Finite Element Method Grain Size (Geology) Laboratory Tests Measures Of Effectiveness Moisture Barriers Moisture Content Prevention Roughness Sampling Serviceability Soils Soil Suction Subgrade (Pavements)

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• Publication/ Report Number:
  FHWA/TX-92/1165-2F
• Resource Type:
  Tech Report
• Geographical Coverage:
  Texas ; United States
• Edition:
  Final Report
• Corporate Publisher:
  Texas. Department of Transportation
• Abstract:
  This report summarizes the results and conclusions of a five-year study of the effectiveness of vertical moisture barriers in controlling the roughness of pavements resting on expansive clay subgrades. During the study, vertical moisture barriers were installed at six sites in three of the seven climatic zones in Texas. Site maps are given for each site showing the location of the moisture barriers and the moisture sensors relative to the pavements along which they were placed. The moisture (suction) was monitored on both sides of the barrier for the remainder of the period of this study. In addition, the surface profiles of these pavements in each lane were measured every six months with the TxDOT 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 suction in each of the locations. The program was then used to perform a study of the effects of climatic zone (five cities across Texas were used), degree of cracking in the soil, depth of the root zone, depth of the moisture barrier (4 depths were tried), and lateral drainage condition (3 conditions were used) 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 cracked clay soils and shallow root zones, will show the greatest benefit from using vertical moisture barriers. Measured pavement roughness as indicated by the serviceability index, international roughness index, and bump height are compared with the same values predicted using the computer program and show that realistic trends can be predicted. Appendices show how to measure suction with filter paper and record all of the field measurements of suction and pavement roughness that have been made in this study.
• Format:
  PDF
• Funding:
  Study No. 2/11/8-88-1165
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:0fef0c258f8873a70cc7f44e98707320e80bfe8f527368d2b45cd2529395157830c77aa8ea72ba8278afebe5deafb16548f2cc040d19780f8eeae1f1e64445a2
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/84929/dot_84929_DS1.pdf
• File Type:
  [PDF - 5.12 MB ]