Why have cracks formed across the center of each curved portion of our exposed aggregate sidewalks? Joints were provided every three feet in the straight portions and every six feet in the curved portions.
Six-foot intervals are frequent enough to more than accommodate all shrinkage cracking. They may not be frequent enough to prevent cracking caused by bending, however. The subbases on which sidewalks are placed are often incompletely compacted, especially where the soil has been disturbed during building construction. Eventually uneven settlement leaves the walk without uniform support and it cracks. Good compaction and more frequent joints are preventive measures.