We get all sorts of calls for advice on sculpting and casting concrete: "How can I make my concrete smoother?" is a common question; "What should I use to hold the form together?" is another; and sometimes someone will ask, "How can I make my stepped waterfall look more realistic?".
Concrete, being so inexpensive and easily manipulated for sculpting purposes, has become an increasingly popular medium in home landscaping.
Whatever the inquiry might be, there is usually one thing that stands out -- "How do I roughen up the surface of my concrete?" If you're looking to add texture to your new concrete sculpture, here is how you can roughen up the surface of a newly poured slab.
If you have any cracks or damaged areas, use a concrete grinder to remove them. You can also do this with sandpaper if the damage is not too severe. If large chunks are missing from your slab, now might be a good time to think about patching those holes.
Step 3: Concrete Surface Preparation
The first step you should do is concrete surface preparation. It is important to get the ground ready before you begin to sculpt it, but of course, do know the type of surface profile you want on your concrete surface before you start.
Concrete surfaces must be prepared for two reasons: first, because they are not naturally very absorbent, and second, adding color or texture material is easier when the surface has been roughened up a little bit.
Additives can be made from sand cement, latex paint, or paper pulp. There are many different additives you can use to roughen concrete surfaces, depending upon your needs and preferences.
You will probably want to apply an additive, especially if the poured surface is left smooth after curing for a few days following mixing. If no additive is used, it may be necessary to scratch up the surface with sandpaper or a steel brush before adding color and texture.
Surface preparation begins with shot blasting. Shot blasting is a process that uses steel shot and air pressure to roughen up surfaces that you want to be textured or colored, such as driveways, sidewalks, garage floors, patios, and other poured concrete areas.
Shotblasting can be done either before or after the pour depending upon your needs and preferences: if you already have the concrete poured, then you would need to blast it before adding color or texture; if your pour is still in progress, then blasting can be done at any time after the forms are removed.
Shotblasting removes small aggregate pieces and leaves behind a non-directional pattern that blends well with both flat areas (such as patios and driveways) and areas with a natural slope (such as walkways or hills).
One of the easiest ways to roughen up a smooth surface is with a point or a needle tool. There are different types available, but you don't have to spend much money on them. A simple "G," "H," or "I" hand rake will do a nice job as it helps you etch well without acid etching and won't break the bank, unlike acid etching. These mechanical methods are great because they would allow you to roughen concrete with a sandpaper-like finish.
These tools allow you to texture concrete in an artistic way that conveys movement and randomness without being too precise, which might spoil the effect. It's easy to go overboard with these because they're so effective. Think of the end result as looking like smoothly raked gravel after rain rather than sand between your toes.
Concrete can be textured before or after it has been set, depending on how hard you want it to be. The tools above are used in concrete while still in a malleable state and can take some abuse. If you want a roughened surface that is harder to touch, texturing should occur after the concrete has cured.
Another way to surface prep or roughen up concrete is through water jetting. Water jet cutting uses a high-pressure stream of water that cuts into the surface with no dust or vibration, allowing for clean and precise engraving on any material, including concrete, stone, metal, glass, etc.
Water Jet Cutting is fast becoming an industry favorite because it is cost-effective and clean. This method of texturing a concrete surface is often used in restoration work where old or damaged surfaces must be restored to their original state without tearing up the entire area, which would include landscaping and asphalt.
The main reason for using water jet cutting on a smooth pour is to create an intricate design or pattern. Water jet cutting is great for artistic effects because the precision of the cut allows you to customize your textured concrete.
Grinding is another way to roughen a concrete surface by removing it completely. The grinder has a diamond-tipped head attached to a steel shaft. It spins at high speed, allowing the user to grind down surfaces without having them come in contact with anything other than air - thus preventing dust from being kicked up into the atmosphere while working.
Grinding is a great method for prepping concrete that has been shot blasted or needle scaled because it removes the roughness and provides an even surface to work on. The grinder head allows you to apply more pressure than what's possible with hand tools such as rakes and picks, so be careful when using this tool because too much pressure can cause damage to the concrete.
Concrete grinding is a great way for contractors and professionals to smooth out surfaces, making them ready for staining or sealing. The downside to the grinder is that it leaves a very rough finish after you complete your work and requires extra attention in regard to sanding, which is time-consuming and difficult to do by hand.
Sandblasting uses air pressure and fine particles of abrasive (such as aluminum oxide or silica carbide) that are propelled onto the surface at speeds over 600 miles per hour, removing anything in their path with ease.
Sandblasting can be used on any type of material and works well on concrete, which is why it's a preferred method for concrete surface prep. Sandblasting can be used to remove old paint from brick or metal structures in preparation for repainting them and remove rust spots from various metals such as steel beams and aluminum siding.
Abrasive blasting is most often done with a special type of nozzle called an abrasive blast head. The head is attached to the hose and contains small holes or openings through which air passes under high pressure.
The process begins by blowing (or forcing) air out through these holes at very high speeds, carrying with it tiny pieces of sand that act like microscopic jackhammers, breaking down the surface material. The resultant dust is then sucked up by a vacuum system or filtered out with an air filter.
Abrasive blasting can be used to clean off old paint from rust on metal beams and structures and remove imperfections from brickwork in preparation for repainting it.
Acid etching is a process that uses an acid solution to remove the top layer of concrete (typically about 0.125 inches). Acid etching is often used for decorative purposes and can be applied to concrete that has already been roughened by needle scaling or shot blasting.
Acid etching works faster than other methods such as water jet cutting, grinding, sanding, etc., but it also requires the use of protective gear like gloves and goggles because it's a caustic acid.
Step 4: Allow 24 hours before applying paint or other finishing products so that it dries completel4
Once you have roughened your concrete surface and achieved the perfect concrete surface profile, it's time to apply the sealant. However, be sure to allow 24 hours for your surface to completely dry before applying paint or other finishing products because it could affect the consistency of the finish you are about to apply. There are many different types of sealants on the market that vary in cost and durability, so experiment with various sealants to see which one will work best on your concrete surface.
Step 5: Repeat these steps as many times as necessary until you achieve the desired concrete surface profile
Repeat this process several more times if necessary to achieve a deep profile that will hold onto whatever coating product you choose to use on top - thus protecting against harsh weather conditions and giving them a clean look without peeling off over time.
If you are trying to achieve a specific surface profile, make sure that you do not go over it too many times, or else the concrete will be damaged and may even collapse. If this happens, your only option is to start again from scratch.
There you have it, seven different ways to roughen a concrete surface.
In conclusion, there are several methods that you can use to prepare your concrete surfaces for sealing and painting depending on the tools that you have access to, as well as time constraints such as the availability of sandblasters or acid etching services in your area. So experiment with various techniques until you find one that works for your taste.