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Are you planning on new concrete surfaces, but don’t know which exposed aggregate concrete would make the best one? Or maybe you’re just looking for more information on the topic?
No matter what the reason is, I’ve gathered 4 common ways to make exposed aggregate surface on the concrete. You can compare these ways and make a decision on what would fit your way of working the best or which one is the best fit for you.
For a unique and special touch, consider transforming your concrete with techniques to create exposed aggregate concrete. There are four techniques that you can use to create the exposed aggregate look for your DIY project for example.
Each of them works well in specific instances, but all result in a beautifully exposed aggregate finished product. There are 2 instances actually, either the concrete is old and has cured ages ago or it is in the process of making. I’ll cover both of these with two examples to pick from.
Read on to find out more about which technique for creating the exposed aggregate is right for you.
Brushing and washing
The brushing and washing technique is perhaps the simplest way to get the aggregate in concrete to show. It is best used in smaller applications instead of large projects. It can be done without any dangerous chemicals or special tools.
Essentially, this technique of exposing the aggregate stones in your concrete is nothing more than spraying or sweeping the cement paste off from the aggregate that lies under the paste. Use a stiff broom or a steady stream of pressurized water to gently remove the cement paste without harming the aggregate.
The reason I say this is better for smaller projects is that washing big areas of concrete that are curing with water is usually a bad idea. It will mix the water/cement ratio on the concrete resulting in not so optimal strength. This is why I prefer the next method over this.
Also, this technique must be used at the proper time (i.e. when the cement paste is still soft but the aggregate is solidified and will not get dislodged from the strain) so it can be hard for beginners. I’d advise getting a little bit of experience before doing something like a whole driveway, few self-made concrete pads could be a good start.
Surface retarder
Another way you can achieve the goal is by using an exposed aggregate concrete retarder on the surface of the concrete. This chemical is designed to keep the cement paste from setting so fast, giving workers a longer period in which they can scrub off the cement paste to expose the aggregate rocks.
This spray is applied directly after the concrete has been laid, allowing the concrete layers to hold off on the exposing process for about twenty-four hours. Using this chemical allows larger jobs to be done over a much longer period of time than would usually be allowed without the retardant.
For this reason, it’s much better for beginners. Well, I’ve worked with concrete for years and I’d use it as well. The extra time with curing concrete is always a blessing when we don’t want it to get hard too fast. It will help everyone with getting better results. So I’d advise going with this if you’re considering exposed aggregates.
Sandblasting/washing
The last method of creating exposed aggregate concrete is to use a sandblaster to erode the cement paste away from the rock. The good side of this method of doing it like this is that it can be applied to old concrete. By old I mean on concrete that was laid years ago.
The major disadvantage of this method, however, is that the blasting process can chip and wear down the aggregate rock, sometimes even fracturing the individual pebbles. Also if you do it with dry sand you will need some protective gear for your eyes and lungs. With water, it’s good to have protection as well as the sand and loose concrete can cause real harm as it’s blasting on high pressure.
This leads to a bit more worn appearance, and the aggregate is not nearly as shiny as it could be using one of the other methods. If you are looking for the best method to preserve the color and beauty of the individual pebbles, this method should be avoided.
Acid washing
I put the acid washing to the last spot as it is a little bit harder to do than sandblasting/washing to old concrete. There are also more limitations as it is harder to do walls than it is doing floors and the workers also need some more protection.
In a way it is gentler way to expose the aggregates than working with sand, but on the other hand it is harder to control where it goes like with the exposed aggregate concrete wall case.
The process is most of the time watering the concrete, applying the acid with spray or another method. Then you need to wait for some time, depending on how strong the acid is. Then it’s washed and neutralized and washed a few times more.
Proces is repeated to get the results you want. The thing is that it can also damage the concrete so it should be carefully done.
Conclusion
The four basic techniques to creating a “pebbled” look in your concrete floor, patio, or walkway give anyone a variety of methods to choose from. There are few differences in the texture, but a lot of it is also about how you like to work.
While it is the easiest, the brush and spray method is also the method that gives the worker the least amount of time. To remedy this, you might consider using a surface retardant to slow down the concrete’s setting process.
However, if your concrete is old and simply needs a new face, the blasting method might be the best option for you as the acid can be difficult to work with. These four methods have all been known to produce good results and can change your concrete from a dull floor to a beautiful and natural piece of art.
What is common for all these methods of working is that you need to take few steps in protecting the surroundings. Acid washing can be bad for the green life, sandblasting will produce lots of sand and concrete dust, and washing fresh concrete will create some dirt as well.
