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The effect of the use of boiler slag (BS) and fly ash (FA) admixtures in cement-lime renders for an application in repair of salty masonry was investigated. For masonry walls with high degree of salinity, renders with incorporated BS were designed. For structures of a low degree of salinity, external renders were prepared without BS. The mix of perlite and silica sand was used as fine aggregate. In all prepared materials, methyl cellulose was added. In chosen mortars, ethylene vinyl acetate copolymer was inmixed to improve functional and performance characteristic of final products. For the developed renders, comprehensive tests of fresh and hardened mortars properties were conducted, including the measurement of adhesion, water contact angle, mercury pore size distribution, thermal properties, frost and chemical resistance. The microstructure and morphology of the developed mortars was observed using scanning electron microscope SEM. The hardened products were analyzed also by Fourier transform infrared (FT-IR) spectroscopy. The designed renovation renders have satisfied the criteria of WTA 4–9-02 directive. The renders yielded compressive strength from 5.1 to 6.9 MPa. Frost resistance was greatly improved by the 20% replacement of Portland cement with FA. Base coat renders exhibited good resistance to Na2SO4 crystallization. The use of ethylene vinyl acetate copolymer enhanced the adhesion of renders to substrate.
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