New Court Construction

The preparation of building a Sport Court is involves creating a proper foundation and for the post-tension concrete slab of the court. The “foundation” of the court’s slab is made up of three main components, the subgrade, subbase, and vapor barrier. The subgrade is the “earth” or area where the court will be built on. It is the existing soil/land where the area will sit. This area is first “graded” to level give the future concrete slab  a proper slope, starting with the subgrade itself.

After the subgrade has been measured, leveled, and graded, the subbase is added. The subbase is a foundational base of support for the concrete slab that goes on top of the subgrade. The existing subgrade soil may be to weak, rocky, unstable, and maybe just not a proper foundation to support a concrete slab. This is where a different, proper subbase can be used to support the slab. For example, if the subgrade contains a lot substantially large rocks that do not allow for proper ground compaction or the slab will be used for the support of heavy loads, then it is necessary to use a subbase that is stronger then regular earth to support the load. Generally, the proper subbase material for a general purpose concrete slab is Aggregate Base Course (Commonly known as ABC). The subgrade should be compacted is possible and applicable. The subbase must be compacted.

The last foundational component necessary for the construction of a post-tension sport court concrete slab is a vapor barrier. A vapor barrier is a type of layer that goes between the subbase and concrete slab. Its purpose is to prevent vapor from the subgrade and subbase to travel up to the concrete slab. This is vital for sport courts because moisture that comes from the bottom of the slab, up and through the surface of the slab can cause the paint surface of the slab to “peel” and become unadhered from the court’s surface. The typical vapor barrier used for a concrete slab is a 10 mils polyethylene tarp. The tarp goes over the compacted subbase and should cover the entire subbase area.

The next step in the court construction process is the forming of the court itself. Before the concrete is poured, it needs a mold where it can be held together when it is in it’s fluid form. This concrete molding process is called forming. Special wood boards are used to build the container where the concrete will be poured in. The court is measured and precisely squared to create an accurate shape of the dimensions of the court being built. The wooden forms/boards are then framed around the full perimeter of the court’s measurements. The court is now ready to be poured.

After forms have been set, the court area is ready to have the post-tension cables installed. Post-tension cables are a form of concrete reinforcement. Decades ago post-tension reinforcement systems for concrete were on the high-end of the pricing scale, but during the last two decades, post-tension cable concrete reinforcement systems have became fairly affordable. Post-tension cable reinforcement systems are a huge advancement in structural steel reinforcement material for concrete reinforcement. Unlike rebar which is a sedentary steel bar that is used to fight tension forces against concrete by holding the concrete together through  a “grip” force, post-tension cables hold concrete together through live potential kinetic energy forces.

The way post tension cables work is that they are installed inside the slab area after the court has been formed an dis ready to be poured. The court is then poured with the post-tension cables about halfway between the bottom and top of the slabs bottom and top surface. After the concrete has cured for about one to two weeks, the post tension cables are pulled and tightened from one end of the court to “squeeze” the concrete slab together. Every single post-tension cable installed in the court is tensioned. If there is ever a concrete crack that occurs within  concrete slab, the tensioned cables pull the court inwards towards its center, making the crack more or less disappear and never allowing it to grow.

Back to the post-tension cable installation, the cables are installed in a grid-like pattern from north-to-south and east-to-west sides of the court respectively.

The concrete pour is the placement of the fluid concrete inside the formed slab area. Before the concrete trucks and concrete pump truck arrive, the forms are sprayed with forming oil on the inside face of the forms so that the forms do not stick to the surface of the wood forms when the concrete has cured enough to remove the concrete forms. It is similar to adding Pam cooking spray to a pan so that the food will not stick to the surface of the pan. The first big machinery/truck to arrive for the concrete truck is the concrete pump truck. This truck connects to the concrete mixer trucks, takes in the concrete from the concrete mixer trucks, and pumps the concrete all the way to the court through a hose that can be manually or remote controlled to move around in the inside area of the court to pour the concrete.

The concrete mixer trucks are the next trucks to arrive which as sated above, hook up to the concrete pump trucks and begin to feed into the concrete pump truck. The concrete is then poured in the court, and all the foremen and concrete workers begin pouring, leveling, screeding, and bull floating the concrete as it is poured.

Once the concrete is poured, the concrete finishing process becomes the main focus.

The concrete finishing process assures that the concrete is properly leveled and has the proper texture for the sport court resurfacing tasks. The concrete is finished multiple times with different tools and equipment as the texture and curation process of the concrete changes and advances. After court has been properly finished,  given a proper surface texture, and cured out enough to hold the load of a person, the court is covered with another polyethylene tarp to allow for a proper hydration process within the concrete. They hydration process of concrete is what commonly known as “curing”. However, hydration of concrete is the proper name for the chemical reaction that concrete undergoes as its chemical properties use water to harden the concrete material. Industry standard for concrete to cure has been 28 days for many years and continues to be the industry standard for a “maximum” concrete strengthening time duration. However, with new advancements in concrete mixtures, this concrete “strengthening” (also known as curation, hydration) happens a lot faster.  The polyethylene tarp allows the concrete to go through the hydration process more efficiently because it keeps the water and moisture in the concrete within the slab without letting it quickly escape and evaporate. It is important for the concrete slab to keep its own moisture with the help of a vapor barrier on top of the finished concrete slab for the first 3 to 28 days so that quick moisture loss does not occur, and the hydration process of the concrete can be supplied proper water moisture contents.

After about 2-3 days after the concrete has been poured, the post-tension cables are given a slight pull to tension them. The pre-stress is a minor concrete compression force in case there is any early cracking that occurs during the hydration/curing process, to not allow such cracks to grow any bigger and stop them as soon as they begin.

The concrete forms can be removed after 7-10 days of the day when the court was poured. After the concrete forms are removed, if it has been enough time for the concrete surface cover to support the hydration process of the concrete slab, then the concrete surface cover can also be removed. 

The final post-tension cable pull/stress/tension is performed after about 7-10 days after the court has been poured. By this time the concrete forms must have already been removed to allow for the final post-tension cable stress. The concrete slab is now fully tensioned with many post-tension cables, each tensioned at 2500 PSI, all fighting tension forces that can be affecting the concrete slab. Any crack that comes up on the court is most of the times reduced to a hairline crack throughout the lifetime of the slab thanks to the live compressive forces of the post-tension cables.