The following basic principles must be observed in developing a correct jointing detail:
1. Never taper concrete down to less than 2 ft (610 mm) in width.
2. Depending upon the amount of transverse reinforcing steel, be careful of the number of lanes that are tied together. In JPCP, tying more than three 12-ft (3.7-m) lanes together may result in uncontrolled longitudinal cracking.
3. Always design the secondary (intersecting) route as independent in movement from the primary route. Thus, as the primary route expands and contracts, no unnecessary forces will be created in the secondary route.
4. Provide for expansion wherever payment is interrupted in its longitudinal direction.
5. Terminate joints at 90° to any intersecting joints, obstructions, or edges of pavement.
6. Where possible, lay out lane widths of the same dimension. This permits the contractor to pave all the lanes without changing the paving machine setup dimensions.
7. Unless unavoidable, all joints should be in a straight line. Curved joints are difficult to saw and generally require additional forming.
8. For plain (nonreinforced) concrete pavement, the slab length/slab width ratio should not exceed 2:1.
Intersection details should always be included in construction plans. A proper jointing layout ensures that cracking occurs at locations where load transfer exists (contraction joints) and away from wheel paths (longitudinal joints). The jointing detail should be a separate detail in the plan to eliminate confusion and allow field personnel to easily lay out the intersection without construction delay. Figures 3.4 and 3.5 show jointing layouts that have been used for typical intersections.
