A guide of things to consider before installing concrete. It is safe to say that very few exterior concrete installations happen under what would be defined as absolutely ideal conditions. Considerations would include :
- Relative Humidity
- Wind Speed
- Curing Conditions
- Sub-Base Condition
- Access Condition
- Adequate Skilled Labor
- Availability of Concrete
Things to consider before you start
It would be wonderful to have perfect weather on installation day, followed by at least 7 days of optimal curing conditions, but rarely will everything be perfect. A couple of additional things to put into place include:
- A very tight, well-compacted base with no spongy soft spots is a definite advantage.
- Good access for the ready-mix truck or concrete buggy will certainly contribute to a timely placement.
- Plenty of highly skilled finishers sure makes it easier to produce a high-quality job. You’ve got to love it when your A-Team shows up.
Once the Concrete is Ready
The ready-mix dispatcher said he can get concrete out to you anytime you need it and they are only five minutes from your job site,…perfect!
Now, back to the real world. Concrete contractors don’t wait for ideal conditions. There are far too many considerations including scheduling constraints placed there by other owners, builders, inspectors, and underground utility locators, just to name a few.
But, for informational purposes, we can cover some basics to installing concrete here that might be helpful for anyone outside of the concrete profession.
Hot, dry, windy conditions should be avoided. Rapid moisture evaporation at the surface leads to low strength and reduced durability.
Understanding How Hydration Affects Concrete
Going in the other direction, cold weather can lead to slow strength gains and disruptions to the chemical process known as hydration. You can’t fully restore this process once it has been disrupted or halted. This will result in lower strength concrete that will lack important durability characteristics.
The hydration process of concrete involves the chemical process initiated the instant that water comes into contact with the cement particles in the mix. Hydration is dependent on two factors, available moisture and the internal temperature of the concrete.
During hydration, the cement particles combine with moisture to create a paste. This paste soon becomes a gel and it begins to take the form of crystals that reach out in all directions.
This gel will encapsulate sand particles and attach to larger aggregates. It becomes the binder, the glue holding all components together into what appears to be a solid mass.
This gel hardens and the concrete begins to take a set. Hydration continues on for hours, and then days as strength is gained. Eventually hydration slows, but can continue, to a small degree, for months or even years.
Most slabs on the ground such as sidewalks, driveways, and floors will attain about 70 percent of their intended design strength in 7 days. Full design strength is reached at or around the arbitrary 28-day mark used by the industry as a benchmark.
For adequate hydration, we need proper curing conditions. Most critical is that first 7 days when we are shooting for 70 percent of design strength.
Optimal curing conditions require an internal temperature of at least 50 degrees Fahrenheit. Curing also requires an internal humidity of at least 80 percent. These levels of temperature and humidity are critical throughout the entire 7-day process.
Freshly placed concrete should not be exposed to temperatures below 32 degrees during the first 30 days. Thermal blankets may be used to protect it.
Installing Concrete After the Spring Thaw
Most of the exterior concrete in Michigan is installed after the spring thaws when the ground begins to dry out and firm up, usually around April 1st. The season continues until about the end of October when most contractors are trying to finish up before colder weather sets in.
There are a wide range of products designed specifically for the challenges presented by adverse weather conditions.
By taking the appropriate precautions in conjunction with the use of these products, many weather-related challenges can be successfully navigated while producing a high performance concrete installation.
Let us show you how high-quality concrete can be constructed and maintained to give you the performance characteristics necessary for long-term durability. The kind of durability that makes a difference. The level of durability that can pass the test of time while exposed to the most severe service conditions that a Michigan winter can produce.
Ready to Get Started?
Please call today to talk about future projects or existing concrete protection or strength enhancement. Precision Concrete is happy to provide a free estimate for your concrete project.