Why Do Concrete Driveways, Aprons & Floors Crack?

concrete-cracksWhy Does Concrete Crack!?

One of the most frustrating aspects of construction is finding cracks in projects requiring concrete. Concrete is known as an incredibly tough substance, so it seems like a completely safe bet to have it put down in your home or business. Sometimes just as the job is over and, as quickly as a couple of hours  after the concrete has been poured, cracks appear. It hasn’t even finished setting yet! What causes such a thing?

Factors in Concrete Cracks Occurring

There are many factors that can make a concrete floor crack during the setting process or later down the road. All of them are frustrating, but they are very preventable. All it takes is a little research and careful planning.

The first place for error lies in the foundation. This is also probably the most forgotten and most common reason for concrete floor cracks. It is necessary to compact the soil under the concrete so that it is smooth and, most importantly, solid. Otherwise, the concrete will try to fill in uneven spots that form from the shifting soil.

Another reason is that concrete has to cure at the right speed and temperature. If it is too hot when pouring the concrete or if it has sat too long after being mixed, it will begin to cure incorrectly. The moisture can’t evaporate the way it should or be able to fill the space the way it should to form a lasting structure.

It is also very important that the water in the mix evaporates evenly from the concrete as it sets. After compacting the soil, it is necessary to lay down gravel to make a space under the concrete for the water at the bottom of the concrete slab to evaporate at the same speed as the top. Uneven drying times cause cracks because there isn’t proper support for the top half of the concrete that is already beginning to dry.

Cracks Happen Because Concrete Contracts & Expands!

Floor slabs must always be reinforced with rebar or wire mesh. It is inevitable that concrete will “move”. It expands and contracts in cold and hot temperatures and reacts to pressures. The reinforcements ensure that the concrete moves as one big piece, limiting the ability for cracks to form.

Planning of the concrete slab should included properly spaced expansion joints. This means that before pouring the concrete, one must place a fibrous “wall” in proper places to break up the concrete slab. When the concrete expands and contracts as it is naturally inclined to do, it will have a place to expand to without hitting something so hard that either substance cracks under the pressure.

This all may sound complicated, but it only amounts to proper planning and proper mixing. With these ideas in mind, it is possible to do a little research and do the perfect job alone, or to make an informed choice of professional.