There are many types of concrete and it is important that you use the correct type (mix design) for your job.
What are you pouring?
The first question we will ask you is what are you pouring? We are not trying to be nosy. In order to help you choose the right kind of concrete for your project a few simple questions need to be answered.
Strength is one of the most important things.
Concrete’s strength is measured primarily in PSI (pounds per square inch). This is the compressive strength of the concrete. The amount of downward pressure the concrete can support when placed on a non moving substrate. The strength of concrete you need is determined by its use.
Freeze Thaw Protection.
Another important consideration is whether or not your concrete is going to be exposed to freeze thaw conditions after final placement.
In order to make concrete more durable when used in a location where it will be routinely exposed to freeze thaw conditions, an air-void system must be created. This air-void system allows water, which expands about nine times in volume when it freezes, to come out of the concrete without causing the “top to pop off”.
How to Protect Exterior Concrete in Cold Climates.
We protect “outside” concrete by increasing the air content of the concrete. We also must ensure that the air-void system is aligned to allow water to easily escape.
There are two types of air that can be found in concrete; entrapped and entrained Air.
Concrete always has some naturally occurring (entrapped) air in it. Entrapped air is measured as a percentage of the concrete’s total volume. Entrapped air is composed of random air “bubbles” and is usually between 1-3% of the concretes volume.
We need to introduce some additional entrained air into the concrete and ensure that the entrained air’s “voids” line up into continuous capillaries. These capillaries provide a path for the water to escape as it freezes.
Entrained air is introduced through the addition of an air entraining admixture. When using an air entraining admixture for protection in freeze thaw conditions we shoot for a total air volume of 4-7 percent. (Including naturally occurring entrapped air and chemically introduced entrained air).
Size of Aggregates.
Concrete in its simplest form is composed of sand, rock, cement and water.
Slabs footings and walls typically use 3/4 rock. Grout to fill the cells in concrete block some topping mixes and concrete going into Insulated Concrete Forms (ICFs) usually use 3/8 rock.
We will be happy to discuss with you what you will need for your application.