¿Are sawed contraction joints needed for roller-compacted concrete pavements?

Sawed contraction joints for controlling random cracking are not required in RCC pavements due to the fact that RCC has lower water and cement contents than conventional concrete, and thus shrinkage is reduced. Random shrinkage cracks typically occur at 20- to 60-ft intervals, depending on the RCC properties and pavement thickness.

The primary reason for sawing joints in RCC pavements is to reduce or prevent random cracking. On certain projects where efficiency of aggregate interlock or increased load transfer at the joints is critical, joints are sawed to minimize crack openings through reduced saw joint spacing, compared to longer spacing of random cracks. Widely spaced random cracks can have wider then desired crack width. The improved aggregate interlock increases load transfer across the joint. Furthermore, reducing random cracking is sometimes desired for aesthetic reasons.

When used, transverse sawed joints are typically spaced at intervals of 15 to 20 ft for pavements less than 8 in. thick, and 3 to 4 times (in ft) the pavement thickness (in in.) for pavements 8 in. thick or greater.

Cutting joint with early-entry saw

Because the longitudinal loading of RCC pavements is different than the transverse loading and causes more of a hinge action, the spacing of longitudinal joints is typically smaller than the spacing of transverse joints. For large paved surfaces, such as industrial sites, a square jointing pattern is preferred. The spacing is normally 15 to 20 ft for pavements less than 8 in. and 2.5 times the pavement thickness (in ft) for pavements 8 in thick or greater.

As with conventional concrete, the timing of saw cuts is based on the prevention of raveling and random cracking. Sawing should begin as soon as the concrete is hard enough to withstand spalling damage caused by sawing operations. For increased load transfer through aggregate interlock, the depth of the saw cuts should not exceed 1/4 of the pavement depth. Thin early-entry saws are being used more frequently because of the speed and convenience they offer. Sawing can begin within one to four hours after final compaction. The sawcut depth for early-entry sawing ranges from 1 to 1.25 in. regardless of the pavement thickness.