How to Prevent Cracks in Concrete Surface

Compiling the information from the Troubleshooting newsletter of the American Society of Concrete Contractors, here we present some of the best tips and tricks to prevent cracks in your concrete floor surface.

However, first it is essential to know ‘why concrete cracks’.

When installed perfectly, concrete is the most long lasting and durable foundation you can use for your home, warehouse, office and any other construction. In fact, there exist concrete floors in Midland country that are more than 50 years old and are still in good condition.

But it is vital that contractors follow proper guidelines during concrete placement. Below are the five main reasons that cause cracks in concrete:

  • Surplus amount of water in the mix
  • Fast drying of the concrete
  • Wrong strength selection of concrete
  • Absence of control joints
  • Concrete poured on frozen ground

Here are some proven tips to prevent cracks in concrete floors:

Properly compacted subgrade

Preparing a perfect base for a concrete slab is vital to ensure its good performance. Any excavation under the slab should be received back to grade in properly compacted lifts. If these excavations are not working upon while backfilling, this unclutched soil will settle gradually leaving the surface area without base. Either you on your own should learn how to compact soil before pouring the concrete mix or hire a contractor who knows his job well.

Change the concrete mix

Low water to cement ratio is one of the main reasons behind the poor quality of concrete slab. Maximum.50 water to cement ratio is recommended for concrete floor more exposed to the freezing air, moisture and deicing chemicals. And keep water to cement ratio .45 at maximum when concrete is exposed to severe sulfate conditions.

The penetrability of water rises exponentially when water to cement ratio in concrete is more than .50. The lesser is the permeability of water, the higher is the durability of concrete. Strength increases with lower water to cement ratios.

Build in joints

Concrete isn’t a pliable material, meaning it can’t stretch or bend without breaking; it is both a victory trait and a losing trait of concrete. Its unmatched hardness and great compressive strength are two main reasons why concrete is the first consideration in the construction business. But concrete does shrink, expand and move – different surface areas move in different directions. And this is when the installation of joints comes in the picture.

With joint installation, you can control where the cracks can occur. When the stress over the concrete slab exceeds its capability to hold itself together, it will start shrinking at a rate of around 1/8 inch per 20 feet. And while the concrete shrinks, it will start cracking randomly. But you can control this random cracking by pre-determining the location of joints.

Cure the Concrete

Once the concrete is placed, it increases in strength quite rapidly for 3-7 days of time span. Concrete floors that are moist or water cured for 7 days are 50% stronger than uncured concrete floors. All the anticipated properties of concrete floors can be enhanced with right curing method.

High strength, long lasting and crack resistant concrete floor doesn’t happen accidentally. The mixture needs to be ordered, installed, finished and cured with utmost care. Make use of concrete floor polishing equipment to give final touch to the concrete surface and make your floor look visually appealing. Many contractors offer polished concrete management services. Hiring their service at a regular interval, your polished concrete floor will always remain young and beautiful!


[June 26, 2013]