Technical Report

1. Preface

Today, natural stone paving gains more and more importance.

It is our aim to bring the art of paving back to people's minds and to introduce a larger audience of laymen and professionals to the subject.

The front yard is any visitor's first impression and it says a lot about the whole estate. The driveway leading up to the house sets the tone and raises expectations about the interior, telling a lot about the lives of its inhabitants.
More often than not, however, both the designing and the actual building process starts inside the house – consequently, the exterior elements are sadly neglected.

This becomes very obvious in newly built communities or luxuriously reconstructed city quarters. The effort and time dedicated to the façades is diminished by a «detail» such as the path or driveway leading up to the building. A peek over the fence of turn-of-the-century residential buildings, a walk through the city centres of Vienna , Paris , London or Rome shows: in the early days things used to be different.

Why is it that these former standards are rarely ever reached, even with today's financial means and technical know-how? Without question, material and execution play a decisive role besides the design. After the post-war euphoria for «new materials of our times», natural stone paving experienced a revival in the 80ies and was reapplied in many pedestrian zones and squares. However, the times when entire natural stone pavements were covered with asphalt, are not long past.

Natural stone paving does not only look very pleasing but offers some clear practical advantages. For example, with a suitable foundation, it can be used even by very heavy vehicles. Since mechanical forces have increased massively due to high traffic load and climatic changes, the foundation must be built to suit the expected loads and strains.

The construction, the stone and the pointing material all contribute to a natural stone paving which meets today's requirements.

The values of natural stone paving are being recognised again.

2. Foundation

The sub course should always be constructed with materials of soaking quality

  • Temperature changes cause tensions on the surface of natural stone paving and tiling, which leads to condensation in the foundation.
  • If the natural stone paving or tiling is laid using cement pointing mortar, humidity cannot pass through the surface.
  • As soon as the surface heats up, humidity cannot diffuse quickly enough, which leads to pressure due to vapour diffusion.
  • If the natural stone paving or tiling is set into mortar or concrete, the situation gets even worse.
  • Non-compacted mortar or concrete is highly absorbent and will therefore absorb a lot of water.
  • If there is vapour diffusion, lime is transported along with the water.
  • These lime residues diminish the adherence between the natural stone and the setting material.
  • To assure maximum quality, natural stone pavements and tiles should not be set into absorbent bedding materials.
  • If the pavement is subject to little pressure the best choice are stone chippings of 3-6 mm or round gravel of 4-8 mm.
  • For heavy pressure areas, such as streets, forecourts, bus-stops etc, we set our natural stone pavement and tiles into permeable concrete PC 200 with stone chippings of 3-6 mm.
  • With these setting materials, no humidity is produced due to capillary effects, which reduces vapour diffusion to a minimum.

3. «Procedure for pointing paving-stone surfaces»

The procedure is based on three important factors

  • The raw material for the pointing mortar SAMCO 88® is 100% natural
  • The key to a high-quality pointing mortar is the right grading. Surface structure and specific gravity of the granular material are highly important. An optimal grading favours the formation of natural pores inside the joints.
  • 85% of the granular material is ground and round with a diameter of 0.2 – 4 mm; the remaining 15% consist of crushed feldspar to provide the necessary hardness.
  • Since pointing mortar is processed with a very high water – cement factor, it is important that (as with SAMCO 88®) the main part of the granular material is round and ground. SAMCO 88® contains no dust particles, therefore no concrete aggregates may sediment when the mortar is mixed, despite of the high water – cement factor.
  • Thanks to its ideal grading SAMCO 88® can be processed with a low water – cement factor.
  • When processed with method A& C®, the pointing mortar SAMCO 88® can even reach the bedding. Thus, excess water is extracted and entrapped air is reduced to a minimum. Since SAMCO 88® gets processed without any chemical additives, a minimum (3-7%) of air spaces is required within the joints. This pore formation makes SAMCO 88® resistant to de-icing salt.
  • These characteristics of the A& C method are very important in achieving a high-quality pointing mortar.
  • Using pointing mortar SAMCO 88® and the respective processing method assures a high adherence to the stone's quarry face.
  • SAMCO 88® is mixed manually or by means of a concrete mixer. The amount of water added depends on the desired consistency.
  • SAMCO 88® is manufactured in a plant compliant with current quality standards. It is distributed in sacks of 25 kg in accordance with SUVA (Swiss Accident Prevention Association) regulations.
  • Cleansing is done by means of a sponge belt. With this cleansing method no additional water or other undesired substances (like wood shavings) is added to the pointing mortar.

4. Advantages

Clearly, natural stone paving is even nowadays a suitable road surface.

The construction, the stone and the joint material combined with the respective know-how are contributing to a natural stone paving meeting the contemporary requirements.

  • If the bedding material has good permeability, the foundation can dry faster.
  • SAMCO 88® (pure natural quartz sand) contains no chemical additives.
  • De-icing salt resistant joints without any chemical additives.
  • Thanks to the patented A&C process, SAMCO 88 pointing material is compressed into the stable and permeable bedding material. An optimal compound of bedding material, paving stone and pointing material is achieved, which assures additional stability.
  • To avoid vibrations by cleansing, the natural stone pavement can be cleansed before the setting stage (approx. 2 hours).
  • Thanks to the patented processing method and the mechanical cleansing, all joints are evenly filled.

This patented processing method
allows for natural stone paving offering
both low-noise roads and
easy-to-walk pedestrian zones.