External cobblestone paving

The cobblestone paving

The external paving in porphyry cobbles, if performed according to the good rule of the art, it does not require an expensive maintenance and it has a good durability, by virtue of the excellent physical-mechanical characteristics of porphyry and of the materials used to seal the joints between the various elements.

The versatility of the floor in cobblestones, moreover, allows to have a wide availability of laying patterns, able to satisfy any requirement.

Possible defects of the paving in porphyry

Often, however, this flooring with the passing of time can show defects visible also to the naked eye, such as the crumbling away of the joints between the individual cubes, which sometimes involves the lifting of the same, or the formation of depressions on the surface, which is no longer planar going to alter all sloping, leading other problems related to stormwater runoff.

What to pay attention to? The phases of the porphyry laying

The laying of the cubes and the correct implementation of the various layers are key factors that ensure the quality and durability of the flooring that you are going to achieve.

This can be simply divided into four phases:

1- The formation of the substrate, which is one of the cornerstones of the installation.
The substrate is the most durable part on which then will rest the paving and on what will be loaded all the concentrated loads and not, so it must remain unchanged over time preserving its physical and mechanical properties.

Once the background was made using ballast made of stone blocks, or with dry mixed soils that then were going to form a layer to be leveled in order to give a proper slope for drainage of rainwater.

Today, however, the substrate is performed by providing a concrete screed consisting of a mixture of sand, gravel, water and cement, with the standard dosage for about 2 q.li mc. This will have a thickness of 10-15 cm with the buried welded sheets of 6 x 20 mm.

The substrate thus produced is always advisable as highly suitable for the realization of all the floors in natural stone.
Obviously it is important to avoid creating problems to the flooring, to provide the proper slope of the surface water with a minimum slope of 1.5 cm per linear meter (> 1.5%), with the establishment of appropriate collection points and water disposal.

It is mportant to point out that a background is executed to perfection is almost always the main cause of localized fractures that inevitably will report on the finished flooring.

To avoid this problem should be avoided as much as possible subsequent shots in the jet and to respect the period of aging and settling of the same, 30 days before proceeding with the construction of the paving.

2- The bedding; speaking of external paving, the best system is the one that involves the use of crushed sand, the diameter of which can vary from 0-6 mm, clean and free of ferrous parts. The sand used for the bedding layer is mixed with dry cement to avoid slopes.

3- Cleaning and leveling are performed after the laying.
With the help of special brushes, you will have to clean the surface of the pavement and all the spaces left between one element and the other, filled with mixture of sand and cement.
Subsequently, with the aid of hammers, you will compress the individual pieces in the bedding until their final location.

The leveling is performed at least in two stages to be carried out along two mutually orthogonal directions.
Before you perform it you will have to cover the entire surface with a layer of water so as to make the bedding layer more walkable and facilitating the settlement of the final paving.

4- Sealing is the last phase of the work; This is performed by spreading on the paving, after the beating, a layer of fine sand with a diameter varying from 0 to 4 mm, trying to fill all the interstices through the use of special brushes.

Then proceed with the drafting of the slurry obtained by mixing sand, water and cement.

This mixture, once lying on the floor, must compacted every joint between the individual elements of porphyry, and to make sure that this operation is carried out to perfection, use is made of rubber brushes.

When you realize that the gripping phase is starting the operator will start cleaning the floor, with a jet of water that will remove the grout in excess.