Cement is ideal for larger tasks, whilst concrete is ideal for smaller operations. Concrete, one of the toughest and most durable materials known to man, is used to construct schools, bridges, sidewalks, and countless other structures. It's easy to mix - just add water! - and it hardens into a strong, smooth surface. Concrete must be mixed properly before use; otherwise, it will not set up properly and will become useless for its intended purpose. Mixing conrete requires knowledge of chemistry as well as experience. The three main ingredients in concrete are sand, gravel, and cement. These components should be mixed in proportions that will provide sufficient strength when hardened. Cement serves two purposes in concrete: It helps bind the material together and it provides substance for its odor, color, and flexibility. As far as durability is concerned, concrete remains one of the most durable building materials available. It can withstand heat from the sun and extreme temperatures from cold to hot. It does not break down over time like wood does. However, this advantage comes with a cost - concrete surfaces tend to look dull and worn out after years of use. This is because it is difficult to paint or stain concrete. The best way to make it look new again is with a concrete resurfacing project. The interior of a concrete building will also show signs of wear and tear over time due to movement of foot traffic.