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Grouting mortar for stone paving: dry-placed mortar (MMSP) and self-compacting expansive mortar (MEA)



Natural stone paving or granite pavers require mortar to fill the spaces between the blocks or slabs. Non-cementitious mortars currently available on the market have low frost and abrasion durability. For their part, cementitious mortars with latex do not allow the reuse of historic paving stones recovered during repair or reconstruction work, since the mortar with latex cannot be removed from the surface of the paving stone without risking damaging it. These problems are solved by this invention which includes two types of mortars.


This first invention aims to replace the jointing sands stabilized by polymers currently on the market for the jointing of natural stone pavers which are little stressed by the passage of heavy vehicles. Developed for grouting pavements in urban areas (residential streets, parks, public squares, etc.), MMSP has the following advantages:

  1. A very fast and very simple installation.

  2. Very good durability to freeze-thaw and mechanical abrasion.

  3. Stable mechanical characteristics (3 to 7 MPa in compression).

  4. Very good resistance to cracking (self-healing).

  5. Resistance to erosion caused by water spray during cleaning operations.

Self-Consolidating Expansive Mortar (MEA) – for paved driveways

This second invention aims to replace the self-compacting latex mortars currently used for grouting pavements that are heavily stressed by the passage of heavy vehicles. Specially designed for thoroughfares such as those in the historic district of Old Montreal, the increased mechanical properties of MEA greatly surpass those of current joints on the market and therefore minimize maintenance costs. The great fluidity of MEA allows it to be poured directly into the joints without using vibration. In a few days, the water reacts with the cement to develop good mechanical properties. MEA contains additives that provide excellent freeze-thaw durability without the addition of latex. It has high resistance to cracking and self-healing ability. Mortar can easily be removed from the surface of pavers that are salvaged from underground reconstruction or repair work.


The two types of mortars developed (MMSP and MEA) perform better than the commercial products they are intended to replace:

- Increased durability: to freeze-thaw cycles, abrasion/erosion, prolonged humidity and resistance to cracking.

- Economic: at purchase, at installation and in the long term:

  • MMSP and MEA: equivalent or lower raw material cost.

  • MMSP: 50% reduction in installation labor. In a single installation step (vibration and humidification), it can fill joints less than 5 mm wide and more than 100 mm deep.

  • MEA: 25% reduction in the workforce. Does not stain pavers. The absence of latex makes it easier to clean the surface of the pavers.

  • MMSP and MEA: reduced maintenance costs through increased durability.

  • MEA: significant reduction in intervention costs by reusing paving stones. MEA mortar does not contain latex, which makes it possible to reuse old pavers that have already been grouted with this mortar.



- Improved performance: 

  • Resistance to abrasion/erosion/compression: 2 times higher.

  • Freeze-thaw and prolonged humidity durability: 3 times higher.

  • Deformability and self-repair: self-repairs in the presence of microcracks caused by mechanical stress or thermal stress.

  • Increased joint filling capacity and mortar compactness.


- Improved performance: 

  • Compressive strength: equivalent to competitors (25 to 35 MPa).

  • Abrasion/erosion resistance: equivalent to competitors.

  • Freeze-thaw and prolonged humidity durability: equivalent.

  • Deformability and self-repair: self-repairs in the presence of microcracks caused by mechanical stress or thermal stress.

- Optimized mortar-cobble adhesion: the mortar-cobble adhesion stress has been limited to less than 1 MPa in order to facilitate the recovery of the cobblestones and to prevent excessive resistance/adhesion from causing the cobblestone to crack, two problems conventional mortars.


Grouting natural stone paving:

  • Institutional (cities, public places)

  • Industrial

  • Residential (landscaping)


Operating licenses available


Test boards were built in partnership with the City of Montreal at four different sites to assess:

  • Ease of installation: the contractors noted a 50% gain in installation.

  • Performance and durability in service: very positive comparative results after 1 winter.

Project Director: Josianne Vigneault

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