Concrete remains one of the cheapest and most durable products on the market. Learn the stages and be ready to take on the perfect patio or sidewalk project.
To get started let's know what concrete is!
Concrete has been around for hundreds of years and is primarily the combination of Portland cement, stone, sand and water.
Extreme environments may require additional chemicals to control the setting properties, these chemicals are commonly called admixtures. Admixtures also assist with workability, durability and setting time. Admixtures are typically for the professional
When the materials are mixed together, specifically water, a chemical reaction occurs called hydration which binds all the materials and forms concrete.
Types of concrete finishes
Commonly referred to as textured or imprinted, stamped concrete is designed to look like Brick, flagstone, wood or tile.
A rubber mat is used in various sizes and shapes to create the texture and dye to give colour. Quality stamped concrete is an art that requires the right equipment and experience to produce a good look.
A process where a stencil is pressed into the fresh concrete forming the joints to create the illusion of tile, cobblestone or various other patterns. Color is added to enhance the illusion. Stenciled concrete can be a do-it-yourself project as patterns are only limited to your creativity. The difference between Stamped concrete and stenciled concrete is that stamped has a unique texture throughout while stenciled typically relies on the joint pattern to create the illusion.
Float and Trowel Finishes
The trowel tools are used to create a unique pattern of swirls, arcs and textures.
A total utilitarian finish, it is what we all imagine when someone mentions a patio, driveway or sidewalk. Broom finishes are easy and offer a non-slip surface.
Rock Salt finishes
Broadcasting fine water softener salt crystals onto fresh concrete, after setting the salt is washed off leaving a pattern of small holes.
Product can be ordered using a specialty stone as the aggregate or specialty stone can be broadcasted over fresh concrete. The broadcasted stone is trowelled into the concrete. When the concrete has set up the top surface (Portland slurry) is washed away exposing the aggregate.
What to understand when ordering concrete
Steps in the process
Set forms- Forms basically keep the concrete where you want it to be. Forms can be sheets of plywood, cardboard tubes or dimensional lumber. All forms need to be able to withstand substantial pressure from placement. Make sure they are level and square as removing is more work than putting it in!
Convince friends- Everyone wants to help and gain the experience at another person’s home. Friends are notorious from cancelling at the last moment, make sure it is clear than you need them to arrive on time.
Order concrete Generally ready mix companies have two concerns;
1. That you get the right mix for the application. Talking to the dispatcher is always the best approach, they will be able to advise you based on the application the mix that you need.
a. Strength- The ready mix company will walk you through this however you may hear terms like MPa or psi. These are simply the strength of concrete you require whereby MPa is metric and psi is imperial. Typically exterior slabs require 32 MPa 5-7% air and aggregates able to withstand freeze thaw.
b. Slump- This term refers to how loose the product is or how easy it flows. The lower the slump the more stiff it is. The ready mix dispatcher will send the right slump for the project and the truck operators are professionals and more than willing to assist by adding water to increase the slump.
2. That your site is ready and you have the people so they can get on their way quickly. Ready Mix companies have a schedule to keep and managing time on site is critical to that schedule. All to often operators arrive on time to find the site not ready.
a. Have all your forms set the night before pour day, there will always be some last minute adjustments.
b. Make sure your helping hands arrive on time and that all equipment is ready.
Place concrete- Concrete can be placed using wheel barrows, pump trucks, line trucks or conveyors. The most important thing is access for the truck and an understanding what is required to get the concrete in the forms. Consider ramps and shoots based on the site application.
Screed concrete- This is the process of forcing the product into the forms level. On a slab you may use a large piece of wood and pull liquid concrete into the form. The goal is to fill all crevices with concrete level to the top of the forms. Make sure you tap all the forms to limit any honey combing.
Float- The act of further consolidating and forcing liquid to the top.
Control joints- Control joints placed 4-5’ apart on a slab help to predict where the crack will occur.
As with all projects start small and as confidence and skill grow so will your tolerance for risk. Another great way to reduce risk is to hire a professional consultant that will be there to guide, while your friends provide the labor. Some of these consultants even have stamps to rent.