Resurfacing mortar for low-thickness imprinted pavements

As previously mentioned, a screed mortar is used when looking to make an imprinted concrete floor less than 10 centimeters. Whether it is due to aesthetic tastes and preferences or because there is not enough height to apply a thicker imprinted mortar.

It is important to underline that a screed mortar can be used both to renew and rehabilitate an existing pavement, as well as to execute a new one. In the case of an old concrete support, if for whatever reason it could not be applied the screed, it would be necessary to compact the ground and raise it to reach the desired height to then be able to apply the product.

In addition, the Topciment® Overlay is equally optimal for both outdoor and indoor spaces and perfectly withstands freeze-thaw cycles.

The system for making traditional imprinted concrete, that is, with an imprinted mortar or wearing layer, does not differ much from the application process of a screed mortar.

It is essential to clean and prime the support correctly.

Make expansion joints and the relevant cuts.

Apply the appropriate bonding bridge to the support.

Use a good release agent, stamp the pavement with the chosen mold and seal it with a high-performance varnish.

Important: Knead the screed mortar using a stirrer or concrete mixer and mix it with water and polymer, if it is not incorporated in the product. The Topciment® Overlay already includes the polymer, so you will only need to add water to the mix.

Depending on the formula of the screed mortar and the manufacturer's instructions, the mixes will be one or the other. As a general rule, the recommended proportion of water can range between 12% and 20% relative to the mortar. In the summer season, in those cities and countries where it is very hot, the amount of water needed can increase. In the Topciment® Overlay, the proportion is 5L of water per 25K of mortar.

Next, we are going to detail the most common problems that can occur, and in fact do occur, when applying a screed mortar. Mistakes to avoid at all costs to prevent greater setbacks over time.

1. Forget about the expansion joints

It may seem like a basic obviousness how to make expansion joints is not done with the accuracy that an imprinted pavement requires. A more common mistake than we would like and that causes the imprinted concrete to end up breaking due to unwanted cracks caused by pressures from temperature changes and/or seismic movements. Especially on those surfaces heavily trafficked by heavy vehicles.

2. Do not make perimeter joints

The perimeter joints represent the separation of the coating with respect to the structural elements of the pavement. Their main function is that the mobility of the coating is not compromised. Therefore, the perimeter joints should be placed at all the encounters of the imprinted concrete floor that is going to be made with the screed mortar. If not done, cracks will appear sooner or later in the pavement.

3. Not respecting the mixing ratio of the screed mortar

It has already been detailed previously the importance of strictly following the instructions of each manufacturer about the kneading and mixing of the screed mortar. If not, not only will the consistency of the product be disrupted, but also the drying times and, what is more important and serious, the mechanical resistances will decrease. With lower performance, lower quality and product guarantee.

4. Not taking into account the slope of the pavement

Special attention must be paid to the unevenness of the surface so that it does not exceed 15%. If it exceeds this figure, we will find more than palpable thickness differences in the slopes of the imprinted concrete floor. An inequality that would crack the pavement.

Like any product, the cost of it does not depend on a single element, but is subject to several factors that determine its value. The quality of the screed mortar, the labour and dimensions of the pavement to be renovated, as well as the thickness of the product itself are just some of them.

If we stick strictly to the product, and approximately, in Spain the price per m2 of the screed mortar can be around 15-30 euros.

Not only is it possible, but it is an excellent solution. The screed mortar promotes optimal heat transfer from the radiant floor to the room or area in which it is located. But not only that, but it also minimizes possible heat losses to the layers located below. An advantage to which must be added the lower energy expenditure and, therefore, the economic savings over time.

The only thing is that a start-up protocol for the underfloor heating must be carried out to avoid shrinkage cracks. Therefore, the screed mortar must be applied precisely on a radiant floor and the temperature must be gradually increased.