ADHESIVE-STRENGTH ASSESSMENT OF LIME INJECTION GROUT USING STANDARDISED AND MODIFIED TEST METHODS

The adhesive strength of non-structural lime-based grouts used to stabilise sensitive, detached, decorative plasters is an important mechanical property. However, it is difficult to determine it due to the lack of suitable standard test methods. The existing standard procedures are mainly aimed at testing the properties of hydraulic binders and are not suitable for injection grouts or mortar specimens based on a lime binder. In the present study, the focus is on a comparison of the pull-off results between the standardised method (EN 1015-12) performed on pre-drilled specimens on sandwich panels (PMS) and the modified method using sandwich discs (DSS). It was found that the modified method with sandwich discs (DSS) achieved an up to 58 % higher adhesive strength than the standard method with sandwich panels. In the sandwich-panel specimens, fracture occurred in the grout since pre-drilling reduced the cohesive strength of the grout. For the sandwich discs (DSS), fractures occurred predominantly at the interface between the mortar and the grout.