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A proposal for a test procedure for injection products against rising damp

Ir. Yves Vanhellemont, Ing. André Pien, Belgian Building Research Institute, BrusselsDr. Hilde De Clercq, Royal Institute for Cultural Heritage, Brussels


Introduction

About half of the problems encountered while renovating or restoring buildings are linked to the presence of rising damp and/or the presence of salts (mostly because of the rising damp).

Humidity, due to the presence of rising damp, and salts give rise to many problems (often enhanced by other influences):

• Aesthetical• Frost damage• Superficial or crypto-efflorescences• Hygroscopic salts• Biological damage• …


Introduction

• Capillary absorption of the masonry• ‘Hiding’ of the problems by water- and vapourproof claddings or

renders, do not solve the problems; on the contrary, they may become worse.


Most efficient intervention is the application of a mechanical barrier, with many disadvantages…


… and therefore injections of masonry are much more used in Belgium.


Introduction

Investigation of

• the product• the treatment

To be investigated:

• Identification • Efficiency• Migration of the product

This procedure is a result of own research, experience and literature survey.


Identification

The procedure should serve as a basis for technical agreements, therefore an identification procedure is nevessary, in order to control the production continuity.

• Density• Viscosity• Dry weight: a measure for the concentration of active compound• FT-IR: determination of the absorption spectrum (active compound

AND solvent)


Substrates

Most logic (and inspired by other existing procedures, i.e. WTA, BBA, …) is measuring the efficiency using masonry wallets.


Substrates

BUT: because of reasons related to time and costs, another small-scale test is proposed, using small prism-shaped, fully carbonated, mortar-samples (composed of hydrated lime, cement and sand)

8cm

4cm 16cm


Overview

• Sample preparation• Capillary behaviour• Pre-conditioning• Application of the product• Capillary behaviour after treatment• Migration of the product


Efficiency test

• Capillary suction according to EN 1925 (two weeks: saturation moisture content)

• Drying of the samples (45°C)• Pre-conditioning of the samples with a salt solution, containing

NaCl, KNO3, Na2SO4, to saturation degrees of 60, 80 and 95 %• Waiting for one week• Application of the product (1/4th of the normal quantity)• Waiting for 28 days

• Capillary absorption test according to EN 1925 untill constant mass

Afterwards: determination of the capillary water content (taking into account the hygroscopic moisture content of the samples!)


Migration of the product

• Cutting the sample in 2• Drying of the sample (45°C)• Wetting of the surface: distinction between zones where water is or

isn’t absorbed gives an indication of the migration abilities of the product


Conclusion

• Rising damp is a major cause of different kinds of damage to historic buildings.

• Many interventions have been designed, although (at least in Belgium) injections against rising damp seem to be the most flexible and rapid and widely-used intervention.

• In order to make the right choice for an injection product, and to stimulate the industry of developping even better products, a test procedure for testing such products, is important.

• The procedure is a compromise between scientific, economic and time-related issues. An initial test-phase, where also well-known products (both good and bad) are being tested.

• If this procedure gives rise to usefull results, these will serve as a basis for (Belgian) technical agreements. The procedure may also be proposed to (for instance) the CEN TC 346 « conservation of cultural property » (in which both BBRI and KIK/IRPA take place)

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