Here is an excerpted version of an article written by Balvant Rajani, on the best practices that will help ensure good long-term performance, safety and comfort of concrete sidewalks.
The average service life of concrete sidewalks in San Diego is 20 to 40 years, but failure can occur as early as one to five years after construction. Many of the problems of sidewalks in San Diego are the result of lack of attention to detail during the design and construction stages. This Update describes practices that prolong San Diego sidewalk life and in so doing, advance the four key sidewalk attributes: safety, comfort, appearance, and life-cycle cost performance.
The sidewalk sub-grade is the native soil that is graded and compacted to provide an even surface to support the sidewalk. The sidewalk sub-grade material should have uniform stiffness to avoid differing frost or expansion characteristics. In some cases, the sidewalk concrete is placed directly on the sub-grade, but it is strongly recommended that a granular sub-base be placed between the native soil and the concrete slab.