THE MYTH OF SAW-CUT JOINTS IN CONCRETE SLABS AND WALLS

This paper is concerned with the world-wide practice of providing shallow saw-cut joints or v-grooves at regular spacing, for structural purposes, in concrete walkway slabs, slabs-on-grade, and parapet walls. The primary purpose of this paper is to raise awareness among engineers that the practice is a myth and has no structural advantages, and for the engineers to think of a better and more positive/reliable approach to concrete crack control. The other purpose is to make aware the need for engineers to think and observe actual behavior of existing structures, and use that observation to improve future design, and not repeat unsound or useless practices. Elimination of useless saw-cut joints in future construction would save the whole world billions of dollars. The author demonstrates that the saw cuts have no structural impact by showing the pictures taken in New York of typical cracks seen on walkway slabs and parapet walls, and on garage floor slabs that were built with saw-cut joints. Note that this type of actual field observation is more representative than the crack observation on small concrete models tested in any engineering laboratories. For comparison, the author shows the examples of crack-free, maintenance-free garage floor slabs and parapet walls without any saw cuts that have been in service in Thailand for the past 30 years.