Stone reinforcement

The structure of mineral building materials that are exposed to the weather is always weakened. This weakness is usually caused by an expansion of the original pore structure, rarely by a real loss of binding agent. The central task of a consolidation measure is to specifically fill the pore spaces created as a result of the weathering. This occurs by penetration of an additional nature-identical binding agent.

With 'new’ material, for example, freshley mined natural stone, the strength profile is usually homogeneous, which means that the strength and elasticity on the surface of the building material is the same at every point of the cross-section. This condition, which is lost due to weathering, should be restored by strengthening, without impacting on other characteristic building material parameters as well as the strength and elasticity.

The range of weathering profiles is as broad as the range of the façade building materials, starting with different natural stone varieties from bricks and render through to concrete. It is apparent here that different strengthener types are necessary to achieve balanced strength profiles.

Accordingly, Remmers supplies strengthener types that differ based on the following criteria:

• Its ‘level of binding agent’ - the so-called amount of gel separation
• Its gel structure - without or with elastic components
• The type of binder tailored to the substrate

The silicic acid ester itself is a fluid and can be poured into a pore structure without adding solvents. By varying the mixing ratio of small and large molecules, it is possible to vary the properties of a strengthening agent, in particular its gel deposit rate, i.e. the quantity of the silica gel in the pore structure. In addition to the gel deposit rate, there are other variation options with regard to the penetration behaviour, the reaction rates etc. due to changes of the type and quantity of the catalyst and the use of solvents.

Thanks to the targeted combination and variation of these parameters, a range of stone strengtheners has been created that offers extensive selection and adaptation possibilities for substrates that need to be consolidated.

All silicic acid ester based stone strengtheners have one decisive characteristic property that distinguishes them from other strengtheners: The created strengthening silica gel has its own porosity. This so-called secondary porosity preserves the capillarity and water vapour permeability of the strengthened material.