When concrete sidewalks are built, they are perfectly finished and look smooth. But in course of time, the flaws and frailties rear their ugly head and they start cracking or become undulating. Life of a concrete sidewalk depends on the weather, soil and care put to it. Fluctuating temperatures take a toll on the longevity of the sidewalks. Sometimes the soil plays the devil when it shifts gradually due to accumulation of water causing the slab to sink.