MORTARS AND PLASTERS PRODUCED WITH EARTH-BASED SUSTAINABLE MIXES: A METHODOLOGY PROPOSAL FOR RECOVERY OF VERNACULAR ARCHITECTURE IN ROERO, PIEDMONT (ITALY)

Abstract

The work presented is the achievement of a master degree project, developed at Politecnico di Torino. The paper aims to provide standards for the formulation and mixing of earth-based mortars, for the rehabilitation of historic buildings of the Roero area, in Piemonte region. Roero presents a large architectural heritage, consisting mainly of fired or earth bricks rural and residential buildings, which was anciently protected using lime or earth-based plasters perfectly integrated with local landscape and environment colours appearance. In recent decades (and still to present days), vernacular plasters are frequently replaced by cement-based products, resulting hardly compatible with local bearing walls materials and landscape aesthetic features. While Roero traditional buildings plasters were produced using local earth and sands coming from streams, today, aggregates extraction in watercourses proximity is not allowed, or strictly regulated by rules and regional regulations. The paper presents a classification of the characteristics of different soils from Roero area, through different types of particle distribution size analysis and diffractometric tests, and propose a method for the production of local earth-based plasters stabilized with lime, making use of earth and rocks from local excavation sites, considered in Italy as secondary raw materials or special waste. Produced plasters compressive and bending strength have been tested, while their suitability for building maintenance and restoration, as their compatibility with Roero architecture and landscape, have been verified through spectrophotometric measures.