FAQ’s for Concrete Projects:
Listed below are the most frequently asked questions by customers about concrete and things you should know before you commit to a newly poured concrete project.
What is cement and concrete? Cement and concrete often are used interchangeably however cement is actually an ingredient of concrete. Concrete is basically a mixture of sand and gravel or crushed stone and a paste of water and portland cement. Cement comprises from 10 to 15 percent of the concrete mix, by volume. Through a process called hydration, the cement and water harden and binds it all into a rocklike mass. This hardening process continues for years meaning that concrete gets stronger as it gets older.
How long should I wait to walk/drive on newly poured concrete?
Depending on the temperature you can use your new concrete driveway 7 to 10 days after the concrete has been poured. 7 days during the hotter months of the summer and 10 days during the milder temperatures of the spring and fall.
Should you have any heavy traffic such as a dump truck or semi-tractor trailer you should wait a full 14 days.
You should not walk on the newly poured concrete for 24-48 hours.
What does it mean to “cure” concrete? Curing is one of the most important steps in concrete construction, because proper curing greatly increases concrete strength and durability. Concrete hardens as a result of hydration: the chemical reaction between cement and water. However, hydration occurs only if water is available and if the concrete’s temperature stays within a suitable range. During the curing period-from 5 to 7 days after placement for conventional concrete-the concrete surface needs to be kept moist to permit the hydration process. New concrete can be wet with soaking hoses, sprinklers or covered with wet burlap, or can be coated with commercially available curing compounds, which seal in moisture.
How long does it take for concrete to cure? The concrete will take a full 28 days to cure on it’s own and fully dry.
What are the joints in concrete? These are known as control joints and give your concrete a place of least resistance to cracking. Should cracking occur, it should crack along the joint first and hopefully not in random places. They are placed every 10 feet and are either ridged or cut into your cement.
How long do I wait until I seal the new concrete?
You should seal your new concrete within the year it is poured to protect it. The sealant included in the pour is part of the concrete mixture and will only protect the concrete through the 28 day curing process. Sealant can be applied 45 days after the concrete is poured.
For a new stamped/decorative concrete, this will be sealed 14 days after poured.
How do I protect my new concrete?
Apply sealant and have a regular care and maintenance program.
Properly fill around the concrete with soil and or gravel, leaving edges exposed will not protect it from weather and allows moisture to run under the concrete. Planting grass also helps for proper drainage. Exposed edges will also be weak and filling with soil will help to support and avoid cracking and chipping from traffic close to the edge.
Apply sand in icy weather and avoid salt
Will my concrete crack? Unfortunately, cracking is pretty common in concrete, especially during the first 30 days, while it’s curing or setting up. If a contractor does it right and the conditions are ideal, the cracks can be virtually unnoticeable from plain view, except the homeowner’s prudent eye.
There are a number of reasons why concrete cracks. The most common is because concrete shrinks as the excess water evaporates and it hardens. Concrete can also crack if it dries too quickly.
Weather conditions — extreme temperatures, rapid temperature changes or conditions that are too wet or too dry — also play a major factor in how well concrete cures.
Why does concrete pop or flake? Popouts are common in exterior concrete in climates that are subject to freezing and thawing in moisture rich environments resulting expansion. Even if aggregate meets all standard requirements, popouts can occur. In almost all cases, popouts do not structurally impact the concrete. However, if popout have occurred, sealant is even more important, as these areas will allow for absorption of water and chemicals that can cause continued damage.
My concrete appears discolored between sections, will this go away?
If your project was poured with separate batches of concrete, you will notice that there is a color variation between the sections. Separate batches may have to be used if the project is large enough that it requires two trucks to pour or if the project has to be split into separate days due to weather or issues that arise. No two batches of concrete will be the exact same color on initial drying. After 45 days, you should see the color between sections begin to match up as it is bleached out and fully cures/dries.
What is Fiber Mesh? This is a concrete additive that is mixed in with the cement at the ready mix plant. If you could look at a cross section of Fibermesh fibrous concrete, you would see millions of polypropylene Fibermesh fibers uniformly distributed in all directions throughout the concrete mix. These fibers provide top-to- bottom, side-to-side uniform reinforcement and are a cost-effective and superior alternative to rebar or wire mesh reinforcement.
As a standard practice, we pour all projects with 4000PSI Fibermesh reinforced concrete, which we feel is the absolute best form of reinforcement available today.
How thick should my concrete be poured? Thickness is the major factor (even more than the strength of the concrete) in determining a structural capacity. Concrete is to be poured at a minimum thickness of 4 inches. Increasing the thickness from 4 inches to 5 inches will add approximately 20% to your concrete cost, but will also boost the load-carrying capacity nearly 50%. Depending on the traffic you will have or the weight you intend for the concrete area to be able to withstand you may want to increase to 6” or 8”
How do you remove stains from concrete? Common dry methods include sandblasting, flame cleaning and shotblasting, grinding, scabbing, planing and scouring. Steel-wire brushes should be used with care because they can leave metal particles on the surface that later may rust and stain the concrete. Wet methods involve the application of water or specific chemicals according to the nature of the stain. The chemical treatment either dissolves the staining substance so it can be blotted up from the surface of the concrete or bleaches the staining substance so it will not show.