Studies in Conservation Consolidation and chromatic reintegration of historical renders with lime-based pozzolanic products

Historical renders are exposed to several degradation processes that can lead to a wide range of anomalies, such as scaling, detachments and pulverization. Among the common anomalies, the loss of cohesion and adhesion are usually identified as the most difficult to repair; these anomalies still need to be deeply studied to reach compatible, durable and sustainable conservation treatments. The restitution of renders cohesion can be achieved using consolidating products. Nevertheless repair treatments could induce aesthetic alterations, and therefore are usually followed by chromatic reintegration. This work aims to study the effectiveness of mineral products as consolidants for limebased mortars and simultaneously as chromatic treatments for pigmented renders. The studied consolidating products are prepared by mixing air lime, metakaolin, water and mineral pigments. The idea of these consolidating and colouring products rises from a traditional lime-based technique, the lime-wash, widely diffused in Southern Europe and in the Mediterranean Area. Consolidating products were applied and tested on lime-based mortar specimens with a low binder-aggregate ratio and therefore with reduced cohesion. A physicomechanical, microstructural and mineralogical characterization was performed on untreated and treated specimens, in order to evaluate the efficacy and durability of the treatments. Accelerated ageing tests were also performed to assess consolidants durability, when subjected to aggressive conditions. Results showed that consolidants are compatible, effective and possess good durability. Powered by Editor ial Manager® and ProduXion Manager® from Aries System s Corporat ion Consolidation and chromatic reintegration of historical renders with lime-based pozzolanic products P. Pascoal, G. Borsoi, R. Veiga, P. Faria, A. Santos Silva a NOVA University of Lisbon, Faculty of Science and Technology, Civil Engineering Department, UNIC, 2829-516, Caparica, Portugal b National Laboratory for Civil Engineering, Building Department, Av. do Brasil, n.106, Lisbon, Portugal c National Laboratory for Civil Engineering, Materials Department, Av. do Brasil, n.106, Lisbon, Portugal