Overview
In this project EP2, the behaviour of the water absorption of liquid applied waterproofing systems (FLK) will be investigated. The water absorption of FLK due to rain water, dew and air humidity will be simulated and determined with different storage situations. The influence of the water absorption on the interface bonding between FLK and mastic asphalt (GA) will be investigated using different tests in the laboratory and on bridges.
The main goal of the project is to study the water regime of liquid applied water proofing materials and to evaluate simple tests for the verification of suitability and for assessing the fitness of the system installation. The project will:
- investigate the influence of the water regime of liquid applied water proofing materials on the bond to asphalt layers
- evaluate the suitability of applied test methods for the examination and the assessment of the capability of the water proofing system
- evaluate the in situ use of the test methods
- propose requirement values (in the sense of the evaluation of the system suitability) based on determined characteristic values
Funding
Results
Moisture Characteristics
FLK have largely reached a state of equilibrium after being exposed to the open air for around 8 days. With polyurethane-based (PU) systems, moisture absorption and release occurs significantly sooner than with PMMA systems (polymethylmetacrylate-based). With PU systems, over 75% of the moisture absorption and release has already occurred after the first day. The reaction of the FLK to changing humidity occurs correspondingly quickly. Generally, there are no marked differences between the equilibrium moisture content on open film (both sides exposed to water) and aluminium-backed film (only one side exposed to water).
Bond Characteristics
The FLK investigated displayed significantly different results for the mastic asphalt protection layer to FLK bond characteristics. Investigating the bond characteristics involved testing the adhesive tensile strength and shear strength properties between mastic asphalt protection layer and FLK.
PMMA systems generally have higher adhesive tensile strength values than PU systems. At lower temperatures (adhesive tensile strength at 5°C) the differences are more significant than at a test temperature of 20°C. For shear strength, on the other hand, there are generally no differences between PMMA systems and PU systems; one PU system exhibited similar shear strength to the PMMA systems, but the other 2 PU systems exhibited lower shear strength.
It can be assumed that the bond characteristics (adhesive tensile strength and shear strength) are dependent on the hardness of the FLK. Harder systems exhibit higher shear strength than softer systems. It is suspected that the forces introduced to softer systems lead to greater deformation and so to detachment at lower adhesive tensile or shear stresses.
No connection could be found in the bond characteristics between the systems' production conditions and the systems' storage conditions prior to the installation of the mastic asphalt. The anticipated, significant influence of the bond characteristics by the water absorption and moisture behaviours of the fluid polymers was not confirmed. The systems' bond characteristics are not primarily influenced by the properties investigated under the remit of this research project. The bond characteristics of mastic asphalt on FLK are evidently primarily determined by adhesive boundary layer phenomena.
Recommendations for Standardization
The requirements in standard SN 640 450a for
Other results
The characteristic values will form a basis for the fixing of Swiss standard requirements with respect to the EOTA guideline (ETAG 033) for the waterproofing of concrete bridge decks using liquid applied waterproofing materials.