Lime Based Grouts for Strengthening of Historical Masonry Buildings in Slovenia

摘要

Most of the historical masonry buildings in Slovenia were built out of local stone or stone and brick with lime-based mortars. An efficient technique for improving the mechanical properties of stone or stone-brick walls is grout injection. In order to evaluate the quality and compatibility of commercially available injection grouts with materials present in historical masonry buildings, several types of hydraulic lime-pozzolana, lime-cement and cement grouts were tested. Chemical, physical and mechanical criteria to select optimal grout mixture for strengthening of historical masonry buildings were proposed, by which tested grouts were classified in three quality classes A, B and C. Only two commercial lime-cement grouts and one cement grout were able to meet the set requirements and were qualified in class B as medium quality grout (one lime-cement grout) or in class C as low quality grouts. Therefore, the design of hydrated lime-based grouts was carried out in continuation of our study, in order to obtain a grout that is highly compatible with the historical masonry in Slovenia. Among available limes, hydrated lime in powdered state and lime putty were used. Ground granulated blast furnace slag (GGBS), volcanic tuff, and limestone powder were used as mineral additives. It was found that the added combination of limestone powder and supplementary cementitious material (GGBS or tuff) has a beneficial influence on the properties of designed grout compositions.