Concrete is a mixture of cement, water, fine and coarse aggregates which hardens over time. Because of its porous nature, it easily absorbs liquids such as ink, water, or paint. These liquids can deeply penetrate the concrete surface, making it hard to clean it out of the concrete. However, if liquid such as paint pours into the concrete, it can be removed by scrubbing the surface with a hard-bristled brush and detergent and rinse it with water thoroughly. But if the paint has already dried from the concrete, removing it can be challenging and consuming yet it can still be done by following the step by step process below: 

1. Do an initial cleaning routine to prepare your concrete surface for a more thorough stain removal process

You can use a vacuum or broom to get rid of the surface dust or debris. If needed, you can scrape away any loose paint using a brush or scraper. You can also use a detergent solution or diluted trisodium phosphate (TSP) to thoroughly clean the surface while scrubbing it with a brush. Allow it to dry. 

2. Prepare your absorbent paint stripper materials

You will need a reliable paint stripper, like a product with methylene chloride, any absorbent material like clay, or if the clay is not available, you can use a cat litter and crush it into a powder. You will also need a scouring powder and a hard bristle brush. Paint stripper comes in different brands and capacity. If you’re dealing with severely dried paint, you may opt for an oil-based instead of a water-based paint stripper. 

3. Combine the paint stripper with the absorbent material

Make a paste that commensurates the thickness of your paint stripper using your absorbent materials like clay or cat litter powder. This absorbent material should be adhesive enough to stick to the dried paint and take it off the concrete. Lastly, you can scrape off the dried paint using a scraper or a hard brush. 

4. Apply the mixture of absorbent material and paint stripper

Make sure to apply it to the spot where the dried paint is found. Let it sit for around 20-30 minutes to allow it to seep in and work. Depending on the severity of the paint stain, you may leave it for a few minutes to several hours. In some cases, leaving it for a few minutes will do the trick. During this process, you can add more paint thinner to the applied mixture to keep the solution active. 

5. Remove the mixture by scraping it off

Scrap the mixture off using a hard plastic scraper. Just keep on scrapping until everything falls off. The paint thinner did most of the work here by making the dried paint easy to scrap. You can apply the second batch of the paint stripper mixture if you see any remaining paint on the concrete. Repeat the process until the concrete is completely clean. 

6. Do your final cleaning by scrubbing the spot where you removed the paint

Remove any remaining paint particles or traces by scrubbing the area using a stiff brush, scouring powder, and rinsing water. Once everything is clean, rinse it thoroughly with water. Keep repeating this process until the surface is impeccable. 

You can follow the step by step process above if you’re dealing with small to medium dried paint spots on your concrete. However, large spots like a paint spill on your backyard or garage floor need some changes with the entire process. You can follow the same basic steps above with one exception – the layer of paint stripper must be replaced by a paste from the stripper and super absorbent material like a ground clay powder or a powdered cat litter. 

On the other hand, if you prefer to skip using any chemical, and go for more eco-friendly options, you may do that, but keep in mind that this could be more labor-intensive than using chemical removers. But if you have children at home, or you’re simply health-conscious and prefer to stay away from the harmful effects of chemicals, then these are the best options for you. 

1. Soy gel is a non-toxic, biodegradable paint stripper that is made up of American-grown soybeans that can effectively remove paint from surfaces like concretes. It does not contain methylene chloride as most paint strippers and thinners do. 
2. Soda blaster is similar to a sandblaster. But instead of sand, it shoots out sodium bicarbonate (baking soda). You can find some of the soda blasters for rent, or you can just buy a bulk of it in your local store.