Assessment of innovative methods for conservation of earthen surfaces

Project leaders

Loredana Luvidi, Jinfeng Zhang

Agreement

CINA - CACH - Chinese Academy of Cultural Heritage

Call

CNR/CACH 2016-2018

Department

Social sciences and humanities, cultural heritage

Thematic area

Social sciences and humanities, cultural heritage

Status of the project

New

Research proposal

The earth is one of the oldest building materials and the earthen buildings are widely distributed in the world. In 2011, over 10% of the World Heritage properties incorporate earthen structures. The widespread presence of earthen sites in China, which are part of the cultural heritage of the country, has led to this collaboration for the study of conservative treatments.
The conservation of earthen materials presents additional and particular problems due to easy deterioration/low durability of these materials, with respect to the conservation of stones, that must also be addressed when selecting products and methods for treatments. In this project, the theme "earthen materials" will be addressed, based on a comparison of experiences in the conservation and valorization of Cultural Heritage between the institutions ICVBC-CNR and CACH.
Widely spread in many European, American, Asian and African countries, earth structures bear important and significant witness of knowledge, building technics, technological culture that holds unique landscape values besides historical ones. Ecologic material par excellence, earth was used since antique times to build architectural structures; then it went into a period of complete oblivion as a consequence of the wide diffusion of industrial products. Although until a few times ago the use of earth for buildings has been associated with images of poverty, cultural and social relegation, it stands out as a careful way to employ resources, showing implicit, innate and very significant features of sustainability, unlikely ascertained in most common building materials.
Recently, however, its use has become the object of renewed interest not only for developing countries, but also for a new emerging market.
In fact earth:
- is widely available in nature at an extremely low price;
- is used without the necessity of special transformations, requires a reduced energy amount for its processing and allows to work with a minimum impact on the environment;
- gives the opportunity to build high living comfort structures, thanks to its breathability and thermal insulation.
The only drawback of these architectures is the limited durability of the material against the aggressive action exerted by external agents, like e.g. water and wind.
Therefore, the conservation of earthen architecture needs treatments in order to strengthen and waterproofing the exposed surfaces in order to reduce the damage due to the interactions with the environment.
This research program aims to investigate two methods (chemical and physical) for the consolidation of earthen surfaces and the effect these different types of consolidation treatment (both widely used ones and new ones coming out from the research) have on the performance of the earthen surfaces.
The application of chemical products (i.e. TEOS and an ethyl silicate organo-modified) and of the innovative physical method, using a microwave device, for strengthening the earthen materials, will be tested and compared. A part of the project will be to set up the methods and the conditions of application of the selected products. The choice of the chemical products will be discussed within the project based on the experience achieved in the two countries.
An alternative methodology based on physical approach will be developed and tested. Microwave heating has been already used with different degrees of success for the treatments of some biological agents on several materials and supports. On earthen materials, the microwave heating should change the crystal structure of clay minerals and make them less reactive toward water. The advantages of microwaves with respect to conventional techniques, using chemical formulates, potentially dangerous for substrates and environment, are: the safety for the cultural asset and safety for the operator, thanks to the low-interaction with the substrate and penetration depth.

Moreover, an important part will be the selection of tests for assessment of the efficiency and harmfulness of the treatments (i.e. Karsten tube test, water vapor permeability, water erosion test, colour measurements, etc.). The tests can be performed using, only in part, the standard methodologies commonly used for stone materials, due to the poor water resistance of these materials. For this reason, methodologies for the evaluation of treatments will be developed and adapted for these materials and validated through joint measurement campaigns (in Italy and China). An important topic of the ICVBC-CNR is the development and standardization of tests to evaluate the conservation treatments for stone materials; the ICVBC researchers were founding members of the UNI-Normal and participate in the European Commission to develop standards in the field of Cultural Heritage. The collaboration between CACH and ICVBC-CNR, through this proposed experimental project, will lead a critical review of tests for the evaluation of consolidation treatments in order to set up new protocols to be proposed at the European Commission CEN/TC346.
The bilateral cooperation will offer the possibility to have significant and useful impacts: Chinese territory is in fact rich in earthen constructions and ruins, which need to be adequately maintained and protected. As far as it concerns the Italian group, the experience gained in previous projects on earthen buildings in Italy, Morocco, Syria, Sudan will make it possible the exchange of knowledge and experience with the Chinese group in order to set up methods, tools, protocols and best practices for the conservation of earthen materials and therefore for a valorization of the earthen sites.

Research goals

The main objectives of the research project are the followings:

- Exchange and sharing of experiences about methods, evaluation tests, protocols and best practices for the conservation of earthen materials currently used in the two countries.
- Selection and evaluation of the most promising consolidation treatments for earthen materials, based on the experience gained in the ICVBC-CNR and CACH.
- Evaluation of the application of microwaves as a system for strengthening earthen materials, development of a microwave system and its application in situ.
- Assessment of the efficiency, harmfulness, durability and sustainability of the different conservation methods through examination and discussion of the results obtained in the two laboratories and on site.
- Development of protocols for the evaluation and choice of the consolidation methods on earthen materials.
- Contribute to the development of products/systems of maintenance and conservation more environmentally friendly.
- Contribute the valorization of earthen architectural heritage and increase new green architecture.
- Publication of the results achieved in international journals.


The development of this bilateral cooperation, with the exchange of knowledge that will ensue, may also suggest new research topics and determine the establishment of a wider network of partnerships spread to other countries within which each group has already developed contacts.

Last update: 20/04/2024