Drainable joints with many advantages

Permeable paving surfaces with PCI grout mortars

No doubt about it: Paving stones on private paths, driveways and other outdoor areas create an atmosphere and look attractive. Permanently attractive – as long as you lay them according to requirements. Loose subgrades combined with a permeable grouting offers numerous advantages in the private sector or on surfaces not exposed to strong traffic. An essential criterion, particularly in garden and landscaping projects: Rainwater can seep away directly on site with water-permeable joints but rainwater has to be drained off surface areas that have impermeable joints.


Paving stone constructions are still most commonly implemented in open areas on loose subgrades where the paving stones are embedded into a loose gravel bed and then grouted with crushed sand. However, the advantages of bonded construction, i.e. construction with a binder content, can be optimally used in the private sector or in garden and landscape construction. The advantages are clear: A very uniform joint can be produced in bonded construction. For instance, the joints cannot be flooded out in strong rainfalls – a permanent joint support is therefore not required. In contrast to cement-based joint grouts, the majority of the rainwater is directly passed through the permeable joint grout into the substrate.


Drainable grout mortars for moderate loading

Legislation is aimed at permanently sealing as few surfaces as possible. With the water-permeable grout mortars made by PCI, long-lasting permeable paving areas can be produced. "In areas that are not subject to continuous loading, e.g. due to heavy road traffic, the loose construction in combination with water-permeable grouting is usually an advantage", confirmed Oliver Marek, construction products manager at PCI. "PCI Pavifix 1K, PCI Pavifix 1K Extra (for paths, terraces and driveways) and PCI Pavifix PU (for more heavily stressed areas) have proven to be very suitable, dependent on the loading. The necessary joint filling depth is between 25 and 40 mm, dependent on the material and the loading", added the specialist.


A good choice, economically and ecologically

Drainable joints ensure significant relief for the sewer system during heavy rainfall. They therefore meet the requirements of the water resources act, which specifies local drainage. The cost aspect is also positive: The higher the permeability of the surface area, the lower the fee-relevant drainage areas are. "PCI offers a product range with specific advantages for this construction method. The bonded PCI grout mortar cannot sag and cannot be flushed or brushed away. Important: The paving must be embedded firmly and the base layer must be sufficiently dimensioned so that no harmful deformations can occur. Rigid joints cannot compensate for movements of the stones", emphasised Oliver Marek.


Stable and permeable – no contradiction

A successful example for a bonded, yet permeable, paving area is shown by the renovation of the Biedermann Museum in Donaueschingen. The management decided to have natural-stone paving on the 900 square metre area in front of the exhibition building. "The grouting mortar has to be of as high a quality as this material", explained Oliver Marek. "The optimum choice was made with the two-component PCI Pavifix PU. In combination with the drainable base construction, surface water can be reliably drained away", he confirmed. The construction professionals also ensured that the joint depth was 40 mm. This allows the surface to withstand even vehicle payloads. Just as important and practical for the Museum's public area: No weeds can grow through the joints between the stones so the surface can be kept clean easily and with little outlay.

A loose subgrade combined with permeable grouting offers numerous advantages, particularly for moderate loading in garden and landscape construction: A very uniform joint can be produced. The paving surface can also be easily cleaned. The joints cannot be flooded out, even after strong rainfalls – a permanent joint support is not required. The majority of the precipitation water can seep away on site - sewer systems are not overloaded.

Successful renovation of the Biedermann Musuem in Donaueschingen: The drainable joint grout mortar PCI Pavifix PU in anthracite fits in perfectly with the image of the museum forecourt. The natural stones used here are a mixture of Guber quartz sandstone (8/11) and basalt paving rows (9/9). The original colours of the stones are made even more intensive. In order to preserve these nuances even more, the laying professionals first applied the natural stone pre-treatment PCI Pavifix V before they were grouted. They thus created a fine film on the surface of the stones, thereby protecting them. Any contamination present after the grouting material hardened could subsequently be removed more easily.

Long-lasting materials for a long tradition: In order to honour the three historical partnerships between the twinned towns of Sainte Foy-lès-Lyon in France, Oudenburg in Belgium and Lichfield in Great Britain, an 80 m2 floor mural was laid in paving stones in the little town of Limburg. PCI Pavifix DM drain and screed mortar, PUR joint grout PCI Pavifix PU and PCI Carraflott NT thin-bed, medium-bed and flowable adhesive were used here.

Grouting paving stones using slurry bonding, here with PCI Pavifix PU. The drainable joint grout mortar for natural stone and concrete paving is also suitable for moderate loading (historic town centres occasionally driven over by trucks and cars, loading areas, parking spaces, pedestrian areas).