UFC 3-260-02

30 June 2001

(Equation 17-3). The design thickness hd of plain concrete is 457 millimeters (18.0 inches), and

the design thickness he is 488 millimeters (19.2 inches). The value of hE, the thickness of plain

concrete pavement equivalent to the existing thickness of reinforced concrete pavement,

determined from Figure 13-1 using the existing thickness of reinforced concrete pavement of

200 millimeters (8 inches) and S = 0.15 percent, is 241 millimeters (9.5 inches). Substituting

these values in the equation above,

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c. Reinforced Concrete Overlay. A reinforced concrete overlay may be used to strengthen

either an existing plain concrete or reinforced concrete pavement. Generally, the overlay will be

designed as a partially bonded overlay. The nonbonded overlay design will be used only when a

leveling course is required over the existing pavement. The reinforcement steel for reinforced

concrete overlays will be designed and placed in accordance with reinforced concrete slabs on

grade.

(1) Thickness determination. The required thickness of reinforced concrete overlay will be

determined using Figure 13-1 after the thickness of plain concrete overlay has been determined

using the appropriate overlay equation. Then, using the value for the thickness of plain concrete

overlay, either the thickness of reinforced concrete overlay can be selected and the required

percent steel determined, or the percent steel can be selected and the thickness of reinforced

concrete overlay determined from Figure 13-1. The minimum thickness of reinforced concrete

overlay will be 152 millimeters (6 inches).

(2) Jointing. Whenever possible, the longitudinal construction joints in the overlay should

match the longitudinal joints in the existing pavement. All longitudinal joints will be of the butt-

doweled type with dowel size and spacing designated in accordance with Chapter 12 using the

thickness of reinforced concrete overlay. It is not necessary for transverse joints in the overlay to

match joints in the existing pavement; however, when practical, the joints should be matched. The

maximum spacing of transverse contraction joints will be determined in accordance with

Figure 13-1, but it will not exceed 30 meters (100 feet) regardless of the thickness of the

pavement or the percent steel used. Joint sealing for reinforced concrete pavements will conform

to the requirements for plain concrete pavements.

(3) Example of reinforced concrete overlay design. An existing rigid pavement will be

strengthened to serve as a type B traffic area for a heavy-load pavement using a reinforced

concrete overlay. The pertinent physical properties of the existing plain concrete pavement are:

hE = 250 millimeters (10 inches), R = 4.48 MPa (650 psi), and k = 54 MN/m3 (200 pci). The

design (90-day) flexural strength of the overlay is 5.17 MPa (750 psi).

17-8

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