Author
Marta Bovassi
R&D Building Lab, Mapei SpA (Italy)

The development of Mapei's LEGANTE INTONACO VELASCA for the restoration of the Velasca Tower in Milan was preceded by an accurate analysis of the original plaster. The final mix, composed of white cement and selected aggregates, was designed to meet high performance and durability standards.

Innovation and tradition in the historical recovery of the tower

Studying and formulating a new product is always a challenge for the Mapei Research and Development laboratories, especially when creating a product to be used in restoration work on a historic symbol of a city, such as Torre Velasca in Milan.
LEGANTE INTONACO VELASCA is the result of an in-depth study aimed at meeting the need to guarantee compatibility with the original structure, the durability of the restoration work considering the conditions the render will be exposed to, and a perfect match with the colour and texture of the original render using materials of a new generation.
To develop this product a thorough, detailed investigation was initially carried out under the direction of Anna Bravo, Group Leader at Mapei R&D Central Analytical Department, to analyse the composition and colour of the original render. A sample of render was taken on site and, using morphological analysis, thermogravimetric analysis (TGA) and X-ray diffraction (XRD), it was possible to asses the aggregate distribution in the base matrix, along with its colour, grain dimensional distribution and form, mineralogical nature.
A sample of render of Torre Velasca was taken on site and subjected to morphological analysis, thermogravimetric analysis (TGA) and X-ray diffraction (XRD) at Mapei Research & Development Laboratories.

Study and development of the Velasca plaster binder for durability and aesthetics

On the basis of these analyses, a study was carried out to develop a mix made from light coloured binders and a selection of aggregates to create a colour as similar as possible to the original material.
Various samples of this mix were proposed and evaluated together with the Works Director and Local Heritage Authority in order to achieve the best result from a conservative restoration perspective.
The approved mix, made from white, cement-based LEGANTE INTONACO VELASCA with graded aggregates sourced from Bellamoli and Ferrari quarries, was specifically studied to comply with the performance properties and durability required for the material. Apart from evaluating its main mechanical characteristics, particular attention was also paid to its adhesion properties, modulus of elasticity and igrometric shrinkage resistance to ensure the restoration work would remain durable over time.
For Mapei, the durability of materials is a fundamental aspect when developing products. This particular aspect was studied in collaboration with Prof. Matteo Gastaldi from the mCD (Cementitious materials and Durability) laboratory of the “Giulio Natta” Faculty of Chemistry, Materials and Chemical Engineering at the Polytechnic of Milan. 
LEGANTE INTONACO VELASCA underwent accelerated ageing tests by thermal and hygrometric cycles to simulate the effect of temperature variations, rain and infrared radiation. The adhesive properties of the material were evaluated on various aged samples in comparison with the non-aged product, giving excellent results. A durability study was also carried out on the complete restoration system proposed by Mapei: we are only too aware that, when carrying out restoration work on heritage buildings, it is important to supply complete product systems, from the reconstruction stage to final protection.
When renovating Torre Velasca, a specific binder was developed by Mapei to bring the exterior surfaces back to their original colors

Project information

Yard
repair of embedded floor
Location
Milano, Italy
Subcategory
OFFICES
Built in
2012
Opened in
2014
Application
concrete pillars repair and reinforcement
Application Type
Concrete restoration systems
Client
Unipol SpA
Contractor company
CGG SpA - Costruzioni Generali Gilardi
Architects
ing. Costa; prof. Luccini; ing. Franchi
MAPEI Distributor
Spaberg
Credits
Alessando Dalla Savie
Project Manager
ing. P.Costa
Author
Marta Bovassi
R&D Building Lab, Mapei SpA (Italy)
Tag
#architecture
Product Lines
Products for renovation and restoration
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