Things to Know About Concrete For Your Foundation
Many people building a DIY greenhouse will choose concrete for their foundation and need a little extra help understanding the best way to use this versatile material. Even though it can simply be mixed and poured into a form to build a basic foundation, there are several things you can do to ensure it provides the best support possible. By understanding a few things about concrete itself, you can be sure to get the most from your new foundation.
Concrete Has a Long and Colorful Past
Concrete has been used for building homes and other structures since at least the time of the Romans. Even though the composition of the material has gone through numerous changes over the years, much of it has stayed basically the same. In fact, the material the Romans used to build their roads and other structures was stronger and more durable than some of the modern formulations available today. They discovered a few tricks of their own to make the material easy to work with and by adding horsehair and animal blood to the formula they managed to help it dry harder. This extra material provided a small degree of flexibility in the concrete and allowed it to move slightly when bearing a heavy weight to avoid cracking.
Cement vs. Concrete
Many people confuse concrete with cement and even though the two materials are similar, they are used for different purposes. Cement is considered a construction material and consists of limestone, calcium, silicon, iron and aluminum. This mixture is heated to form hard chunks that are then ground down into the powder known as cement. When water is added to this powder, it starts a chemical reaction that binds the particles together very tightly as it dries. There is a wide variety of formulation for cement and the most commonly used type is called Portland cement. The advantage to this particular mixture is that unlike many of the other types, Portland cement doesn’t require a specific amount of water to be added for proper curing. This means that if you use too much water when mixing the cement it will set just fine. Other cement mixtures are very specific in their water content and too little or too much will affect their final hardness and durability.
Concrete is also used in construction and is made from a larger mixture of cement and a number of other aggregate materials like rocks and sand. It differs from cement in that it uses cement as a foundation, but also includes the other materials that are then tightly bound together with the cement in the mixture. This final product is a very stable material that is capable of supporting large amounts of weight for decades. Because of this, concrete is a very popular building material that is an excellent choice for the foundation of a greenhouse.
Drying Time Is Critical
The water used to mix the concrete starts the chemical process of hardening. How fast this water evaporates is very important to the long-term durability of the finished structure. If a greenhouse foundation made from concrete is allowed to dry too quickly it may crack more easily when under load supporting the greenhouse. It’s very important to always be aware of the curing times for the concrete you are using and keep it properly hydrated as it sets. Too much water is bad for the process as well and fresh concrete needs to be protected from rain for at least 12-24 hours to ensure a good outcome.
The last important component to a good concrete mixture is something called an admixture that will produce millions of tiny bubbles throughout the finished concrete. These bubbles are critical for the integrity of the material and will provide the voids needed for expansion and shrinking of the concrete once it sets. The perfect mix of air entraining admixtures in most greenhouse plans is roughly 8% of the total volume of the product. This will allow the finished concrete to create the voids it needs for temperature stability and greatly extend the life of your DIY greenhouse foundation.