THE IMPROVEMENT OF THE DURABILITY AND FROST RESISTANCE OF TRADITIONAL AND HISTORICAL LIME MORTARS BY MEANS OF SURFACE IMPREGNATION WITH LIQUID POTASSIUM SILICATE AND SILICIC ACID ESTER

The research focused on improving the durability and frost resistance of lime mortars. The tests were carried out on traditional lime mortar, but the conclusions can also be applied to historical composites based on lime binders. Surface impregnation with liquid potassium silicate and silicic acid ester was used in the tests. The test results showed a slight improvement in the bending strength of the test specimens. A significant improvement in the physical and mechanical properties (compressive strength, water absorption resistance and frost resistance) was noted. The obtained results indicate that it is possible to increase the durability of the lime mortars without changing their color. In the summary it was noted that surface impregnation of lime mortars with silicic acid ester proved to be the most effective way to improve the physical and mechanical properties of built-in lime mortars, but the higher cost of impregnation, compared to liquid potassium silicate, may be a reason for the limitation of this solution. It was pointed out that surface impregnation is often the only way to increase the durability of brittle composites with low strength.