If you have a concrete garage floor, driveway, sidewalk or patio that is starting to show its age, resurfacing may be just the way to bring back a youthful appearance. It's a project that just about anyone can tackle, and it's a whole lot more affordable than replacing the concrete. Answers to some of the most important questions you may have about concrete resurfacing follow.
What Is Concrete Resurfacer?
Well, for one thing, concrete resurfacer is a lot more expensive than plain concrete. In my area, a 60-pound bag of concrete mix costs $2, while a 40-pound bag of resurfacer runs about $20. Big difference, which might make you want to think about taking the "budget" route by simply mixing up a bag of concrete mix or mortar mix and applying a thin layer.
Don't even think about it! It won't work. Regular concrete does not contain any kind of bonding agent. If it is applied to old, cured concrete, it will not form much of a bond. As a result, the added layer will start crumbling sooner rather than later.
Concrete resurfacer, on the other hand, contains special bonding agents that overcome that limitation. That's why it costs so much more, and why it is so smart to pay that extra amount. I think the real way to compare costs is not to look at the relative expense of bags of each product, but rather to compare the cost of resurfacing a slab versus breaking it up, removing it and pouring a new slab. From that vantage point, resurfacing starts to look like a bargain.
The two main products in the field are Sakrete Flo-Coat Concrete Resurfacer and Quikrete Concrete Resurfacer. They are comparable products, and you should be able to find one or the other at your local building supply or home improvement store. Both come in 40-pound bags, and you are likely to need quite a few of them.
The specifications on the two brands of resurfacer are virtually identical. When mixed to the flowing consistency needed for squeegee application, they offer a compressive strength of 4,500 psi. That's actually a bit stronger than a regular concrete mix.
Resurfacers are self-leveling, meaning that they don't need to be worked extensively to create a level surface. They pour and spread easily, and your only real job is just to ensure that the resurfacer has been spread around the entire surface. You don't have to worry about trowelling to a level surface, which is necessary with new concrete.
Concrete resurfacers are only available in one color - plain ole gray. But they can be tinted with colorants made specifically for concrete products. One thing to consider if you plan to resurface only part of a larger slab is that it is hard to match colors. New concrete looks new, and old concrete looks old. If you really want to make the surface look new again, it's best to plan on resurfacing all of it.
How Much Resurfacer Should I Buy?
It's hard to estimate the amount of resurfacer you will need, as much of the estimate depends on the final depth of the product. The manufacturers claim that one bag poured to a consistent depth of 1/4 inch, will cover 17 square feet. When poured and finished with a squeegee or trowel to an absolute minimum thickness (1/16 inch), you may cover as much as 90 square feet. Most applications will likely be somewhere in the middle of that range.
But that uncertainty isn't as much of a problem as it may seem. You don't have to resurface your entire slab at one time. Most concrete slabs have control joints and/or expansion joints in them, which need to be covered with duct tape to keep resurfacer out. So, just plan on working between the control joints, buying resurfacer as you go along.
What Tools Do I Need?
You may need to buy a few, relatively inexpensive tools to resurface concrete. Here is the full list of tools you will need:
- Pressure washer (preferably 3,500 psi), which you should be able to rent
- 5-gallon bucket (an emptied joint compound bucket will do, or you can buy comparable buckets for just a few dollars each); you will need one bucket for mixing resurfacer and another bucket to hold clean water
- 1/2-inch electric drill with a paddle mixer
- Long-handled broom
- Long-handled squeegee
- Duct tape or thin weather-stripping for temporarily filling control joints
- Concrete edging tool (optional) for finishing edges
What If the Concrete Is Damaged?
Concrete resurfacer will make the slab look a lot better, but it won't fix any underlying problems. Minor cracks can be patched. Oil, grease and paint stains can affect the durability of concrete resurfacer, so you will want to remove them.
What's the Best Weather for Resurfacing?
Concrete resurfacer should not be applied in cold weather. Make sure that the current temperature is at least 50 degrees Celsius, and that the temperature will stay above 40 degrees Celsius for at least the next 24 hours. Also, work when the area is most shaded, or at least when the sun's glare is at a minimum. Finally, make sure there is no rain in the forecast for at least 8 hours after application.