What are the Causes of Transverse Cracks in Rigid Pavements?

Cracks in Rigid Pavement

What are the Causes of Transverse Cracks in Rigid Pavements?

Concrete pavements are classified into three types:

1-Jointed Plain Concrete Pavement (JPCP)

This pavement is made of panels and has no reinforcement, the concrete bears all of the stresses. As a result, the thickness of the concrete and the length of the panels are crucial in this form of pavement.

2-Jointed Reinforced Concrete Pavement (JRCP)

This pavement is made up of panels, and reinforcement is provided in both the longitudinal and transverse directions to withstand high loads. Both reinforcement and panel length, as well as transverse dowel joints, are critical in this form of pavement.

3-Continuously Reinforced Concrete Pavement (CRCP)

This style of pavement has no joints, as the name implies. It is a single continuous slab with longitudinal and transverse reinforcement. Reinforcement is crucial with this type of pavement.

Concrete slabs will always crack, but if the slab is carefully designed and built, the cracks will be minimal and tight, causing no difficulties. To avoid bonding of the slab with the subgrade, which would result in cracks, slabs should be laid atop a cushion of sand or heavy gauge polythene sheet to enable unrestricted thermal expansion and contraction. However, transverse cracks can form in any type of slab for the following reasons:

                                               

1-Jointed Plain Concrete Pavement (JPCP)

The panel is far too long. As the slab has no reinforcement in this situation, it will crack. The length of a slab panel should be kept within the range of loads it can withstand without cracking in order to prevent transverse cracks. Generally speaking, panel length shouldn't exceed 15 feet. Another factor could be insufficient transverse joint width, which prevents the slab from expanding freely in hot weather.

2-Jointed Reinforced Concrete Pavement (JRCP)

Transverse cracks will form in this kind of slab if the reinforcing is insufficient, or the panel length is excessive. The maximum panel length for these sorts of slabs should be 40 feet, and there should be enough steel reinforcing to keep the cracks small and tightly spaced. Similar to JPCP, if the joint width is inadequate or the transverse joint dowels cannot freely slide in the casing, JRCP will similarly break in the transverse direction. If cracks appear in the middle third of the panel in either the JPCP or the JRCP, the panel length is either too long or, in the case of the JRCP, the reinforcement is insufficient. However, if cracking appears close to the transverse joints, the slab may not be allowed to expand freely close to the joints or the joint width may be insufficient.

3-Continuously Reinforced Concrete Pavement (CRCP)

Reinforcement is used in these pavements to keep the cracks tight and properly spaced. These pavements have the most reinforcing. If the reinforcing is insufficient, large transverse cracks with consistent spacing will occur, and the slab will begin to behave like JRCP. Furthermore, if construction/expansion joints are not provided where there is a significant change in geometry, large transverse cracks will form (e.g., at change in sections or at intersections).

Rigid pavements are vulnerable to several forms of failures because of heavy moving loads and slab shape, so engineers must carefully manage the design and construction phases.