Development and testing of grouts based on perlite by-products and lime

Grouting is a widely used intervention technique for the consolidation and strengthening of historic masonries. During the recent decades, lime-based grouts have been developed, tested and applied, taking into account parameters, such as their compatibility with the historic structures and their performance both in terms of fresh and hardened state properties. The exploitation of perlite by-products on the other hand (named as 'waste perlite'), is a field that should be further envisaged, due to the gradually increasing demand of expanded perlite production, as well as the need of minimizing the environmental burden from its industrial process. To this direction, a series of grout mixtures based on two types of perlite by-products (D1S and D1C) and lime (air and hydraulic) were manufactured and tested. According to the experimental results, waste perlite-based grouts presented effaceable fresh and hardened state properties, while their performance was enhanced when superplasticizer and a short proportion of white cement or metakaolin was added in the air lime mixtures. In the hydraulic lime mixtures, the addition of waste perlite enhanced their properties and significantly increased their strength. Therefore, it was concluded that according to specific requirements, both perlite by-products studied could be used in combination with lime, for the manufacture of light-weight, low cost and environmental friendly grouts. Future oriented research should be therefore made in order to further investigate the parameters influencing the performance of grouts based on other waste perlite types. (C) 2019 Elsevier Ltd. All rights reserved.