Highway Engineering

HD 26/01 updated the design for jointed rigid pavements originally detailed

in RR87. The design thicknesses for different traffic loadings are detailed in

Fig. 8.14. The values derived assume the presence of a 1 m edge strip or tied

shoulder adjacent to the most heavily trafficked lane. If this assumption cannot

be made and the highway does not have a 1 m tied shoulder, a thicker slab will

be required and the value derived from Fig. 8.14 must be increased by the

amount given in Fig. 8.15.

Within a jointed reinforced concrete pavement, the quantity of reinforcement

directly determines the joint spacing. If the slab is unreinforced and less than

230 mm thick, contraction joints should occur every 5 m. If the unreinforced slab

is above 230 mm, these spacings reduce to 4 m.

If the jointed slab is reinforced, the maximum transverse joint spacing shall

generally be 25 m. If limestone coarse aggregate is used throughout the slab,

transverse joint spacing may be increased by one-fifth (HD 26/01).

It should be noted that, within the UK, rigid concrete construction is not gen-

erally recommended on trunk roads as it would require asphalt surfacing which,

in the case of a jointed concrete pavement, has been observed to result in crack-

ing and the need for subsequent maintenance. There are instances, however,

246 Highway Engineering

Slab thickness without tied

shoulder (mm)

Cumulative traffic (msa)

0.1 1 10 100

50

150

0

100

200

250

300

Slab thickness with tied

shoulder (mm)

300

250

200

150

R = 0 mm^2 /m

R = 636 mm^2 /m

Figure 8.13Design thicknesses for jointed concrete pavement (M=680 MPa). (Crown copyright
1987)