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.
Highlights
For the restoration of buildings and structures of historical development and the decoration of newly erected objects, dry plaster and render mixes are widely used [1,2]
It was found that the output of the filler synthesized from the water glass in the presence of CaCl2 in the form of a 15% solution in an amount of 30 or 50% of the weight of liquid glass was 85%
The output of the filler synthesized from the liquid glass in the presence of CaCl2 in the form of 7.5% solution in the amount of 30 or 50% of the weight of liquid glass was 100%
Summary
For the restoration of buildings and structures of historical development and the decoration of newly erected objects, dry plaster and render mixes are widely used [1,2]. Since 2015, the construction sector has seen an increase in production of dry plaster and render mixes by 10–25% [5]. The volume of production of plaster, render and putty mixtures is increasing every year, and today it is about 48% of the production of dry mixes [6,7]. Coatings based on lime-based dry mixes are characterized by low water resistance, which leads to increased costs [16]. In this regard, it is urgent to develop a technological solution that increases coatings’ durability based on lime dry mixes [17,18,19]
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