Stone paving stones are one of the most beautiful materials used for paving. It is quite true that they have European elegance and reliability that are difficult to compare.
Paving stone is supplied in several types of materials, including granite, porphyry and even concrete. They can be laid on a sandy foundation if they are at least 60 mm thick and are covered with gravel, sand, resin or mortar. For best results, although they should be glued to a concrete slab, this procedure is discussed in this article.
Paving stones can be purchased either as separate stones, or already glued to the mesh substrate. The mesh provides a faster lining, although they are not always accurate and, if they are glued to a steep concrete surface, the mesh prevents good adhesive contact between stone and concrete and is not recommended for traffic. On level surfaces there are no problems with using mats.
As soon as the stones stick together, the grout can begin the next day. A grout may be a simple sand-cement mix with addition of oxide for painting, if necessary, or a pre-mixed colored solution. The pre-mixed solution is more expensive, but less labor intensive and more consistent in color and hardness.
Problem:
Traditionally, the solution is dissolved in 10 mm gaps using a squeegee or by hand and cleaned with a sponge and water when the solution is partially cured. Over a large area, such as an access road, this is a very slow and tedious process. Granite cobblestones have a rough surface that is difficult to wipe and easily absorbs cement that can leave stains. Subsequently, they can be cleaned with hydrochloric acid, but this requires considerable time and danger of staining the solution.
Alternatively, the stone can be sealed before grouting with high-quality penetrating stone sealant. This will prevent staining. However, since the cobblestone must be clean and dry before sealing, it is not always practical to do a lot of work.
Decision:
Faced with these problems, I was convinced that if I could use an extrusion method, such as a large grouting gun, to make the grout fill the gaps, I could significantly reduce the time on this part of the project.
Some studies have found a very simple device consisting of a PVC cylinder with a replaceable stainless steel nozzle and a manual plunger. Pointmaster was designed primarily to indicate old brick work, but it turned out to be a magic tool for grouting cobblestones.
Using a premixed solution, fill the cylinder. Being careful not to spill them, put the nozzle into the gap and slowly squeeze the grout. To get a smooth flow, some practice (and a strong back) is required.
If you fill the gaps to the top, then let the solution be prepared for about 3 hours. It can be smoothed as low as you want the stone to stand higher. For smoothing, I use bolts of various sizes or even sticks. This is a simple and fairly satisfactory process and gives excellent results.
Advice:
1. Do not try to smooth the solution too early or it will be slow and dirty. Either you have to leave it until the next day, or it will be very difficult to work. What works best is if you wipe in the morning, leave it to set and smooth at the end of the day.
2. While they are noisy and annoying, a sheet blower is the best thing to clear gaps in the stone before mashing and remove debris when the solution is smoothed.
Happy grouting!
