OVERLAY DESIGN AND REFLECTION CRACKING ANALYSIS FOR RIGID PAVEMENTS. VOLUME 2--DESIGN PROCEDURES

This manual presents design procedures for flexible and rigid overlays of rigid pavements as well as a reflection cracking analysis procedure for flexible overlays. The design procedure includes an evaluation of the existing pavement based on nondestructive deflection testing, condition surveys, and materials sampling and testing. Based on this information the pavement is divided into separate design sections and each section is classified according to its condition of cracking into one of the three categories: (1) pavement with no cracking or Class 1 and 2 cracking, (2) pavement with Class 3 or 4 cracking, or (3) pavement that will be mechanically broken up. An analysis to determine the required overlay thickness is then made based on the category to which the existing pavement is assigned. The overlay analysis makes extensive use of elastic layered theory and selects the overlay thickness based on the concept of failure by fatigue cracking. For flexible overlays an analysis can be performed to determine if reflection cracking should be expected occur. The design procedure uses four computer programs for the pavement evaluation, overlay thickness design, and reflection cracking analysis. Input guides and illustrative problems for the use of these programs are presented in this report.