Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
1  Joints in concrete pavements are intended to provide freedom of slab movement induced by volumetric changes due to drying shrinkage, temperature changes, and moisture differences that develop within the slab. A key purpose for sealing rigid pavement joints should be to prevent or limit the intrusion of an incompressible material and to reduce the amount of water infiltrating the pavement structure (which can result in subbase erosion), loss of support, and other water-related distress. The presence of moisture in a pavement structure contributes to a variety of governing distress types that eventually lead to deterioration of a pavement structure and decreased service life. Recently, the effectiveness of sealants to protect jointed concrete pavement against water-related diffi- culties has been of great interest. Portland cement concrete (PCC) pavement joint sealing material technology has evolved in recent decades. Some progress in the configuration, design, preparation of sealants, and, in particular, the design and inspection methods of narrow joint widths appears to contradict established recommendations. Although the practice of joint sealing has long been established, the effect of current joint sealant practice has not been well documented. Therefore, it is necessary to establish a standardized approach to joint sealant evaluation as well as to investigate the practice of joint sealant in PCC pavement design. Information for this report was collected through a literature review, a survey of state departments of transportation, and follow-up discussions with selected agencies for the development of case examples documenting practices. The questionnaire was organized to reflect joint sealant practices and provide insight into selected joint sealant factors (including or excluding joint sealants, joint types, sizes, shapes, and so forth). Questions related to joint installation and timing were also included because the nature of joint preparation can have a significant effect on performance. Questions about joint sealant performance and related types of distress were formulated to examine the correlation between joint well designs and joint sealant performance. Further questions were also included regarding sealant main- tenance and alternatives to the use of joint sealants. The questionnaire had 42 responses (84 percent) out of 50 states. Findings from the survey results and case examples include the following: ⢠Many agencies accept the need for joint sealing and the long-term benefits in promoting quality joint sealant practice. ⢠There appears to be a benefit to documenting or monitoring measures to track the impact of sealant conditions on pavement performance. S U M M A R Y Portland Cement Concrete Pavement Joint Sealant Practices and Performance
2 Portland Cement Concrete Pavement Joint Sealant Practices and Performance ⢠Not all agencies follow established practices regarding sealant shape factor, possibly risking premature bond failure. ⢠There appears to be a need for tools or control protocols to facilitate agency inspection of cleaning and joint preparation operations. ⢠There also appears to be a need for aids and criteria for assessing the benefits of joint sealing, selecting joint sealant, or determining when to carry out resealing operations.
