An overview of the remaining challenges of the RILEM TC 274-TCE, testing and characterisation of earth-based building materials and elements

Based on the RILEM Technical Committee 274-TCE work, this paper is a discussion of the remaining engineering challenges faced by earthen architecture. The assessment of earth material performances requires the development of appropriate procedures and standards. This is discussed in particular for the characterisation, hygrothermal behaviour, mechanical behaviour, and durability of earth materials. One other important challenge, since one of the main advantages classically put forward, is its ecological performance, is a proper assessment of life cycle assessment of earth materials, elements and buildings. Moreover, the paper develops why the approach to earthen construction must be different compared to the dominant construction materials, to preserve its ability to contribute to the ecological transition in the construction sector. In particular, the needs of using local soils, with an architectural approach coping with the limits of the materials, and developing an architectural optimisation to preserve the earthen materials multifunctionality rather than selecting a sole property to be maximised. Lastly, the findings of the paper can be used to develop a holistic approach to earthen construction to foster the development of new earthen architecture projects.

Earthen architecture in the Iberian Peninsula: a portrait of vulnerability, sustainability and conservation

For more than a decade, a wide range of Spanish case studies, relating especially to rural inner or abandoned sites and areas, have been analysed by the authors as part of different research projects linked with traditional and monumental architecture, conservation strategies and earthen buildings. On one hand the studies have been undertaken in the framework of a project concerning the conservation of rammed earth in the Iberian Peninsula, including criteria, techniques, results and perspectives and, on the other, by a project about the conservation and rehabilitation of traditional earthen architecture in the Iberian Peninsula, providing guidelines and tools for its sustainable intervention. In all cases the researchers’ efforts focused on enhancing new perspectives and opportunities for rural earthen buildings, analysing landscapes, contexts, constructive features, decay and problems. The final common aim of this research is to stress these crucial topics to improve tangible or intangible opportunities for conservation strategies.

The involvement of local communities in the conservation process of earthen architecture in the Sahel-Sahara region – the case of Djenné, Mali

Recently, many cultural aspects of some African countries have been in danger of being lost due to cultural disruptions, nonadaptive construction techniques and a lack of adequate conservation systems and strategies. These include the well-known manuscripts of Timbuktu (Tombouctou) as well as architecture, languages, beads, textiles, costumes and other cultural objects. Immaterial heritage, such as oral history, traditional music, instruments and dance, is also affected.In the northwestern part of Africa, the so-called Sahel-Sahara region, earthen architecture has played an important role in cultural identity and has been a key means of community establishment. This architectural heritage includes a wide variety of creations ranging from simple houses, granaries, and palaces to religious buildings, urban centres, cultural landscapes and archaeological sites. By studying northwestern African cultural heritage and cultural exchanges during trans-Saharan trade, we can benefit from traditional knowledge and use these teachings to build a sustainable knowledge system for earthen architecture conservation. This work is urgent since these structures are in danger of being lost, destroyed, badly conserved, or not documented.The aim of this research is to point out, through an anthropological approach, the importance of local community involvement in the conservation process. This research is based on a comparative study of different earthen architecture conservation spaces within the abovementioned region that have been important and were influenced by cultural exchanges during trans-Saharan trade. In these historical towns, some architectural heritage sites have been abandoned and are in ruins, while others have been preserved solely as tourist attractions. In this paper, I introduce the case of Djenné to share our research approach. This paper provides insight into earthen architecture conservation issues and how local communities have used tangible and intangible methods to preserve cultural heritage.

Characterization of materials used for earth architecture in Eastern Croatia

Even though earthen architecture is recognized as cultural heritage in Croatia, most of existing buildings are in deteriorated and heavily damaged state. Until today, there has been no conducted research on earthen architecture in Croatia, nor was any preservation act proclaimed. Therefore, the purpose of this research is to learn more about behaviour of traditional earthen architecture to highlight the importance of sustainable building. For that purpose, earthen houses in Eastern Croatia, mainly Slavonia and Baranja area, were studied and in-situ samples were collected. In order to learn about characteristics and composition of mixtures, five samples were tested. Results gathered within this research will be the first step towards creation of national standard for designing rammed earth structures. In scope of future research, authors are planning to use verified recipe in making of walls that will be tested for seismic resistance.

Earthen architectural heritage in the international context: values, threats, conservation principles and strategies

PurposeThis research aims to highlight the values, principles and recommendations for conservation in order to establish valid strategies for the conservation of earthen built heritage. This is done following a methodology which uses indirect (bibliography) and direct (case study) sources systematically analysed from different perspectives: the values of Earth as a material and of architectural and vernacular heritage; the heritage conservation principles found in international documents; and the analysis of over 3,000 case studies from which good practices in earthen architecture conservation are extracted.Design/methodology/approachEarthen built architectural heritage is found widely in all parts of the world, in archaeological sites and monumental and vernacular architecture, which research centres and researchers are increasingly studying and cataloguing. However, despite its richness and historic and cultural values, as well as its many merits in environmental sustainability, sociocultural and socio-economic terms, the value of this heritage has not been fully recognized in fields with major repercussions in conservation.FindingsFinally, these data are cross-referenced to establish the broadest possible strategies to guarantee all aspects to be taken into account in the conservation of earthen built architectural heritage.Originality/valueThe text provides an overview of the different methodologies in order to extract specific strategies applicable to the conservation of this heritage, both locally and globally.

Experimental Research On the Performance of a Novel Geo-Filament Anchor For An Earthen Architectural Site

An efficient anchoring method, explicitly developed for small sliders, has hitherto been missing in the practice of earthen architecture conservation. Furthermore, anchoring performance studies conducted so far, have failed to fully take into account the soil characteristics of certain targets. To address these concerns, the conservation project conceived for the Gaochang Ruins, Turpan, in China, was selected as the testing ground to design a novel Geotechnical Filament Anchor (GFA) for reinforcing small sliders in the earthen historical ramparts. In-situ experiments were conducted for evaluating six parameters—anchoring length (L), GF thickness (H), bore diameter (D), grouting strength (S), GFA surface status (R), and inclination angle (A). These parameters were varied in order to determine the effect they produce on anchoring performance, as demonstrated by the indicators, including tensile strength, destruction mode, load displacement (P-S) relation, and strain (ζ-L) distribution characteristics of the novel GFA. Data acquired from the experiments, in combination with the conservation specifics of earthen architectural sites, anchoring performance, and safety reserve, were further employed to introduce a calculation formula for computing the designed force value (N) through L. A simplified model depicting the shear stress distribution of the anchoring system under N was devised by extracting the strain distribution data with respect to the GF-grouting interface. Taking into account the soil properties of the above-mentioned site, the shear stress diffusion coefficient (α) was conceptualized, the formula for the shear strength of the grouting material was devised, and the tolerable ranges of L, D, H, R, and S were determined. Thus, a feasible anchoring method for small sliders used in earthen architectural sites is proposed, and validated by strong and reliable experimental and theoretical groundwork.

The technical and the social: challenges in the conservation of earthen vernacular architecture in a changing world (Jujuy, Argentina)

Vernacular earthen architecture presents a series of relevant conservation challenges that involve designing solutions for different kinds of alterations and degradations. Other challenges of a social nature simultaneously arise and are related, among other factors, to the participation of local communities and the actions of different institutional actors. Understanding these phenomena has generally been approached from perspectives that take technical considerations and social dynamics as separate fields. The current global context has resulted in an acceleration of changes in these dynamics, in terms of both techniques and management models, giving rise to the need to develop comprehensive conceptual and methodological approaches through which these challenges should be addressed jointly by recombining the technical and the social.This paper will analyse the main problems affecting vernacular architectures in three communities in northern Argentina, where earthen techniques have been very relevant. We will reflect on various potentially useful theoretical frameworks, incorporating concepts from the anthropology of technology and methodological approaches from an ethnography of conservation as a way to work with multiple ontologies.