The use of zeolite, lightweight aggregate and boiler slag in restoration renders

•We propose a novel render with zeolite for salty walls.•We focused on assessing the usability of zeolite and boiler slag in restoration render.•The frost resistance is nonlinear dependent on the strength properties of the render.

For the protection of walls against salt-damp, various renders with different aggregates are proposed. The purpose of this study is to investigate the impact of natural zeolite, lightweight aggregate and boiler slag additives in the production of cement-lime renders meant for salty walls. The article presents laboratory examinations of their basic physical parameters such as water absorption, capillary absorption, water vapour permeability, absorptivity, sorptivity, density, total porosity, compressive and flexural strength. In addition to studies of the basic physical properties of the renders, frost and chemical corrosion resistance tests were conducted. Special additives to improve the properties were used such as hydrophobizer, methyl cellulose - a water-retaining additive, ethylene vinyl acetate copolymer powder, as well as a redispersive additive to improve adhesion. Apart from white Portland cement CEM I 52.5 R, blast furnace cement CEM III was also used, wherein the composition contains coal ash.The highest efficiency of render corrosion protection was obtained by the renders with Portland Cement CEM I 52.5 R and boiler slag. The experimental results showed that the mortars modified by natural zeolites and boiler slag, thanks to their porous structure, are distinguished by good sorption properties and can accumulate in themselves a sufficient amount of salt and ice.