What is a drywall control joint

During concrete curing, why do people cover it with plastic?

Rapid moisture loss is your enemy

What causes cracks in new concrete? And how do you prevent these cracks? Healing concrete properly while it is fresh can save a lot of hassle later. And the good news is that just covering them with plastic wrap is just huge.

The trick to properly harden concrete

You have probably seen people covering freshly made concrete work with plastic as it cures. Why do you care?

So that no dirt hits the concrete during the curing time? While it's true that covering the hardening concrete with plastic is cleaner, there is a more fundamental purpose:

Remember, you are mixing water into concrete to activate the cement binder in it. When the mixture dries it will harden. But drying or "curing" should be done gradually, otherwise cracks may appear. To prevent cracking, plastic is placed over the hardening concrete to trap the water in it and ensure gradual hardening. As an additional step, you can regularly mist the concrete with a spray bottle to prevent it from drying out too quickly. For an example of a specific project that you would need to cover with plastic, see Creating a Concrete Deck.

Related information on masonry and curing

If you are a handyman who is new to topics like concrete and mortar curing, there are many terms out there that can be confusing.

Let's take a look at a few, with the aim of clearing up any confusion before embarking on your hardscape project. It is better to take a little time to familiarize yourself with this topic than to make big mistakes - maybe even irreversible ones - later when you are working with concrete, mortar, etc.

(These substances can be very unforgiving):

  1. "Masonry": Masonry is built through the use of units of various natural or man-made mineral products such as stone, brick, mortar or concrete. The term masonry can be applied to the vehicle itself or to the finished product.
  2. "Concrete": Concrete is a masonry product made from cement, sand and gravel or other coarse aggregates. When water is mixed with concrete, it activates the cement component, which is the element responsible for bonding the mixture into a solid object. Concrete is often used in hardscape constructions. For example, concrete can be used to form the floor of a patio or concrete foundations can be used to support a wooden patio.
  3. "Mortar": Mortar is a masonry product made from cement and sand. When water is mixed with mortar, its binding element, cement, is activated. You need to distinguish the mortar from the "concrete" which acts in a similar way but contains a coarse aggregate held together by the cement. Concrete can stand on its own, while mortar is typically used to hold brick, stone, or similar materials together. For example, to build a hardscape feature like a brick patio or mortar wall around an artificial pond, mortar would be used to hold the bricks or stones together.
  1. "Drywall": In relation to stone walls, "drywall" is a construction in which the stones are not held together by mortar. The drywall construction requires greater precision in the stacking of stones than with a masonry construction, since the wall remains intact through the correct arrangement alone. The equivalent term for installing paving stones to build a patio or walkway is "dry-laid". Also note that the term "dry wall" used in connection with indoor construction refers to something completely different: namely, the type of board sometimes referred to as "plasterboard".

More about hardening concrete - and mortar - right

That's right: even if mortar is another concrete masonry product, it should also harden properly. And again, improving your chances of curing properly is as simple as covering your just-completed project (like a brick patio held together with mortar) with plastic wrap.

Optionally (to further improve your chances of your mortar setting properly), pick up the plastic occasionally and lightly dampen the mortar with water from a spray bottle. How much time does the mortar take to fully heal? Generally it takes about two days, but that depends on the weather conditions.

But back to the question of the correct curing of concrete. How long it takes concrete to cure completely? There is a technical answer and a practical answer. The technical answer is 28 days. But Aurora Paving points out, "For practical reasons, we recommend that car traffic usually end up on concrete slabs after three days and truck traffic after seven days."

There is one more step to concrete healing. Have you ever heard of a "control joint"?

Control joints are grooves that are made in a concrete surface to "control" cracks. Essentially, this groove is an intentional, controlled crack that is inserted to prevent the concrete from cracking itself in an uncontrolled manner. By making control joints in the material before it hardens, any stress the concrete is subsequently exposed to will not create the random cracks that create a landscape eyesore.

Using a trowel or jointer, cut a uniform control joint that is aesthetically pleasing. Control joints can also be cut into existing concrete surfaces using a saw with a masonry blade.