FACCIATA DELL’EX-HOTEL PALACE IN LUGANO: INTONACO TRADIZIONALE O INTONACO DI RISANAMENTO?

Albert Jornet, Andreas Küng, Guido Corredig

Istituto Materiali e Costruzioni, Via Trevano, CP 12, DACD - SUPSI, CH-6952 Canobbio

Tel.: +41 (0)58 666 63 63; albert.jornet@suspi.ch; andreas.kueng@supsi.ch; guido.corredig@supsi.ch

ABSTRACT

       In the framework of a requalification project concerning a 19th century neoclassic Hotel in Lugano, due to the important presence of salts within the render and the masonry, it was decided to use a restoration render to replace the original one. In this paper we are reporting on the results obtained in a laboratory investigation conducted in order to compare properties and performances of three selected commercial systems.

Consistency, bulk density, porosity and water retention capacity were measured on fresh mortar. For each product, nine standard prisms of 40x40x160 [mm] were prepared, while a slab was used as substrate on which the render system about 20 mm thick was applied. The prepared samples were stored at 20°C and 95 % r.h. for one week and at 20 °C and 65 % r.h. for three weeks. Density, flexural and compressive strength were determined on standard prisms, while capillary water absorption, water vapour permeability and total porosity were determined on cores drilled out of the prepared slabs. Salt crystallisation tests were also performed on drilled cores. In addition, the microstructure of the systems was examined using optical and fluorescence microscopy.

The results obtained show that the investigated systems complain with most of the restoration render requirements according to the WTA Sanierputzsysteme Merkblatt 2-9-04/D guidelines. Nonetheless the investigation allowed the selection of the best suited system for the job.

Keywords: renovation, rendering, moisture, salts, crystallisation