DESIGN ASPECTS OF UNREINFORCED CONCRETE PAVEMENTS

This paper discusses several factors that need to be considered when designing and constructing concrete pavements. These pavements are sensitive to: (1) daily and seasonal variations of temperature; and (2) the axle loads of heavy vehicles likely to use the pavements during their design life. Brief consideration is given to: (1) the factors causing fatigue stress and cracking in concrete pavements; (2) joints in concrete pavements; (3) the mechanism of load transfer at joints; (4) the design of tie bars; (5) steel bars at joints; and (6) methods for the casting of concrete pavements. The author concludes that: (1) actual values of temperature and axle load should be used; (2) the position of the axle load on the pavement influences the stresses generated on the slab; (3) an axle on or near a longitudinal edge generates higher stresses, so that it causes more fatigue damage in the slab; and (4) it is not valid to superimpose independently calculated stresses due to temperature and wheel load. It is recommended that an axle survey should be performed before the pavement is built. The lateral distribution of vehicles across the road width should also be studied before attempting to design the pavement.