Impact of Design Features on Pavement Response and Performance in Rehabilitated Flexible and Rigid Pavements

Appendix D. Practical Guide: Factors Affecting Performance of Rehabilitated Rigid Pavements

Introduction

This appendix summarizes the research results of the SPS-6 experiment to help engineers select the best rehabilitation alternatives for rigid pavements. The selection is based on alternatives evaluated in the SPS-6 experiment and from a performance perspective as a function of specific site conditions and distresses in the existing pavement.

The selection is made based on the best alternative in each group. Despite the practicality of the information, the tables in this section should be used with caution, particularly when the sources of distresses are associated with construction, new techniques, or other unusual circumstances not reflected in the SPS-6 experiment.

The design factors and site characteristics investigated in the SPS-6 experiment were as follows:

• Site conditions: Climate (wet versus dry and freeze versus no-freeze) and pavement condition (fair versus poor).
• Design features: Surface PCC restoration (minimum, maximum, saw and seal, crack/break, and seat) and overlaid (4 and 8 inches (102 and 203 mm)) versus not overlaid.

Selection Process

This section summarizes the rehabilitation alternatives that are most likely to provide best performances under a given set of conditions. Within each group, the impact of design features is characterized by ranking the rehabilitation strategies from the best to the worst. Each distress is evaluated independently. Only rankings with statistical significance are provided in the tables. If there is no ranking associated with one particular distress, no statistical difference in performance was found, which indicates that none of the design features evaluated had differential impact on performance.

The tables can be used as a guide to determine which rehabilitation design alternatives will perform better among the options evaluated in this study. This selection process is only applicable to JPCP sections. The study described in the main volume of this report suggests that all rehabilitation strategies applied to JRCP sections were equivalent in performance when the sections were grouped by site conditions. The number of JRCP sections available was small and significantly limited the results from a statistical analysis standpoint.

An example is described for JPCP and summarized in table 128. To create this table, information was taken from table 129 through table 134 to evaluate which of the design features evaluated in this study would provide better performance as measured by the level of distresses listed in the tables. The selection is made based on the best alternative for each group.

Selection Process Example

An engineer will select a rehabilitation alternative for the following conditions:

• The existing pavement is in fair condition, and cracking is the major distress type followed by a medium level of roughness that should be mitigated.
• The section is located in a no-freeze zone and in wet conditions.

The selection process involves gathering the information from each table containing the ranking of alternatives for each specific condition. Using the information in the example, the best alternatives for wet conditions were taken from table 130. The same process was performed for each of the site conditions. As result, the combination of design features presented in table 128 should provide the best alternatives to address existing distresses and have satisfactory performance over the design life of the rehabilitated pavement. Based on the information in the table, the choice should be crack/break and seat with an 8-inch (203-mm) HMA surface layer because the best alternatives for cracking will not mitigate roughness. In addition, crack/break and seat is the second best alternative for total cracking.

Table 128. Selection of design features to improve performance of rehabilitated rigid pavements (JPCP).

1 inch = 25.4 mm

Table 129. Summary of performance for all JPCP SPS-6 sections.

1 inch = 25.4 mm
¹Indicates that based on the distress survey data for cracking, the alternatives without overlays were found to perform better; however, the user should apply these results with caution. It is difficult to differentiate fatigue cracking from reflective cracking, and it seems that reflective cracking is measured as fatigue, longitudinal, or transverse cracking. In this situation, for overlaid pavement, reflective cracking from JPCP joints may have been measured as one of the categories of cracking (fatigue, transverse, or longitudinal). For nonoverlaid pavements, the joints are not measured as cracking, causing the differences in performance identified in the statistical analysis.

Table 130. Summary of performance for JPCP SPS-6 sections in wet zones.

1 inch = 25.4 mm
¹Indicates that based on the distress survey data for cracking, the alternatives without overlays were found to perform better; however, the user should apply these results with caution. It is difficult to differentiate fatigue cracking from reflective cracking, and it seems that reflective cracking is measured as fatigue, longitudinal, or transverse cracking. In this situation, for overlaid pavement, reflective cracking from JPCP joints may have been measured as one of the categories of cracking (fatigue, transverse, or longitudinal). For nonoverlaid pavements, the joints are not measured as cracking, causing the differences in performance identified in the statistical analysis.

Table 131. Summary of performance for JPCP SPS-6 sections in dry zones.

1 inch = 25.4 mm
Note: Blank cells indicate that no statitstical difference in performance was found.

The performance of all rehabilitation strategies for JPCP SPS-6 sections in freeze zones were equivalent.

Table 132. Summary of performance for JPCP SPS-6 sections in no-freeze zones.

1 inch = 25.4mm
¹Indicates that based on the distress survey data for cracking, the alternatives without overlays were found to perform better; however, the user should apply these results with caution. It is difficult to differentiate fatigue cracking from reflective cracking, and it seems that reflective cracking is measured as fatigue, longitudinal, or transverse cracking. In this situation, for overlaid pavement, reflective cracking from JPCP joints may have been measured as one of the categories of cracking (fatigue, transverse, or longitudinal). For nonoverlaid pavements, the joints are not measured as cracking, causing the differences in performance identified in the statistical analysis.

Table 133. Summary of performance for JPCP SPS-6 sections in fair surface condition prior to rehabilitation.

1 inch = 25.4 mm
¹Indicates that based on the distress survey data for cracking, the alternatives without overlays were found to perform better; however, the user should apply these results with caution. It is difficult to differentiate fatigue cracking from reflective cracking, and it seems that reflective cracking is measured as fatigue, longitudinal, or transverse cracking. In this situation, for overlaid pavement, reflective cracking from JPCP joints may have been measured as one of the categories of cracking (fatigue, transverse, or longitudinal). For nonoverlaid pavements, the joints are not measured as cracking, causing the differences in performance identified in the statistical analysis.

Table 134. Summary of performance for JPCP SPS-6 sections in poor surface condition prior to rehabilitation.

1 inch = 25.4 mm
Note: Blank cells indicate that no significant difference in performance was found.