To ensure the concrete pavements we are building now will continue to serve the needs of the traveling public well into the future, it is essential to take into account all design and construction aspects that may impact the performance and durability of the pavement.
Joint design is extremely important, but sometimes not given its due importance in an overall pavement design. A proper jointing system for concrete streets ensures that the structural capacity and ride quality of the pavement is maintained at the highest level of performance at the lowest possible cost.
A proper jointing system will control cracking; divide the pavement into practical geometric increments for construction; accommodate slab movements; and provide sufficient load transfer. Concrete pavement joint design has evolved from a tremendous body of theoretical studies, laboratory tests, experimental pavements and performance evaluations of in-service pavements. Understanding project-specific considerations such as traffic and environmental considerations is of paramount importance in design of slab dimensions and jointing details.
The primary purpose of joints in a concrete pavement is to control the location of transverse and longitudinal cracking, which results from stresses caused by normal drying shrinkage, temperature and moisture differentials, and applied traffic loadings. If the stresses are not relieved, uncontrolled cracking will occur.
Designers also must consider climatic and environmental conditions; slab thickness; load transfer; shoulder, curb and gutter construction; and traffic. It's important to note that late or improper joint formation may cause cracks to occur at locations other than those intended.
For more on the story, read the January issue of ROADS & BRIDGES magazine.
