Modified Lime Binders for Restoration Work

Abstract

Lime mixes are the primary material for restoration work in historic buildings. The research object of this study is modifying lime binders with specially synthesized calcium silicate hydrates (CSHs). This study aimed to improve lime render mixes’ weather resistance. The following factors were considered: the density of the liquid glass, the amount of the precipitating additive, the rate of introduction of the precipitating additive, the drying mode of the precipitate, and the storage time of the precipitate. The research methods were X-ray diffraction analysis, differential thermal analysis, Fourier transform infrared spectrometry, and optical and electron microscopy. It was revealed that lime compositions with CSH have a higher strength gain rate than the control compositions. A mathematical model of the kinetics of hardening a lime composite based on a binder filled with CSH was obtained. The regularities of the change in the lime composite’s strength depending on the filler grinding’s fineness, its content, and the amount of mixing water have been established. It was revealed that the introduction of CSH into the lime composition increases the weather resistance of facade lime mixtures by reducing the porosity and increasing the volume of closed pores of the composite.