Mechanical Properties of a 3D-Printed Wall Segment Made with an Earthen Mixture

This study provides a contribution to the research field of 3D-printed earthen buildings, focusing, for the first time, on the load-bearing capacity of these structures. The study involves the entire production and testing process of the earthen elements, from the design, to the preparation of the mixture and the 3D printing, up to the uniaxial compression test on a wall segment. The results indicate that 3D-printed earthen elements have a compressive strength of 2.32 MPa, comparable to that of rammed earth structures. The experimental data also made it possible to draw conclusions on the action of the infill, which seems to have the function of stopping the propagation of cracks. This has a positive effect on the overall behavior of 3D-printed earthen elements, since it avoids the onset of dilative behavior in the final stages of the load test and maintains ultimate load values higher than 50% of the maximum load.

Starch Reinforcement of Raw Earth Constructions

The restoration, the protection, or the creation of earthen buildings require improving the mechanical strength of the material. The first way to do that is to use inorganic additives, but these additives change the structural properties of earth and have a high carbon footprint. In contrast, the other way to consolidate is the use of organic additives such as vegetal derivatives that rearrange the minerals in the earth, with the lowest carbon footprint as they are from waste management. After preliminary tests with ten different organic additives from traditional recipes, we found that wheat starch improves the earth strength up to 50 %. In this study, we related the mechanical strengthening to the physicochemical interactions between clays and starch. We focus on three clays that represent the three main groups of clays: kaolinite, illite and montmorillonite. For this study, we mainly focused on compressive test and rheological tests. We showed that the improvement of the mechanical strength with starch is depending on clay nature and their chemistry. Then, we can recommend formulations based on the earth nature for new sustainable buildings. Furthermore, we can understand why it was an interesting way to use starch as a strengthening agent in traditional recipes and how it could be used to repair and protect buildings made of earthen material.

Mechanical Properties of a 3D Printed Wall Segment Made with an Earthen Mixture

This study provides a contribution to the research field of 3D printed earthen buildings, focusing, for the first time, on the load-bearing capacity of these structures. The study involves the entire production and testing process of the earthen elements, from design, to the preparation of the mixture and the 3D printing, up to the uniaxial compression test on a wall segment. The results indicate that 3D printed earthen elements have a compressive strength of 2.32 MPa, comparable to that of rammed earth structures. The experimental data also made it possible to draw conclusions on the action of the infill, which seems to have the function of stopping the propagation of cracks. This has a positive effect on the overall behavior of 3D printed earthen elements, since it avoids the onset of dilative behavior in the final stages of the load test and maintains ultimate load values higher than 50% of the maximum load.

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.

Thermal Monitoring and Simulation of Earthen Buildings. A Review

Since ancient times, raw earth has been used worldwide as a construction material. Today, it is well known for its good environmental properties of recyclability and low embodied energy along the production process. Earthen walls regulate the interior temperature of the buildings, providing comfortable temperatures with a very low carbon footprint. As a result of those advantages, earthen building techniques have been revived and used for contemporary architecture. The aim of this paper is to review the state of the art about the thermal behaviour of earthen building, including all the monitoring and simulation analysis of real earthen constructions up to now. The paper presents the different earthen techniques known nowadays, analysing the most important thermal parameters and the thermal comfort achieved with each technique. Regardless the wide differences among the analyzed cases, the authors conclude that earth building is a suitable solution in hot and arid climates, since it preserves the indoor temperature within the thermal comfort limits most part of the time without any active system.

Earthen Architecture in Greece: Traditional Techniques and Revaluation

A big part of traditional architecture both in rural and urban areas in the Greek territory has been built with raw earth. The aim of this paper is to present earthen buildings’ constructions in Greece and show their important contribution to our heritage. The use of earth as a basic constructing material has given different earthen building cultures and techniques. Earthen construction encloses many varied uses and applications, as walls or as plasters. In different periods of time and historical contexts, from the indigenous inhabitants to the neighborhoods of the refugees of Asia Minor Catastrophe, the earth constructions had a primary role. The existence of earthen architecture was investigated in urban and rural sites in Greece. Building information, documentation, and records of buildings’ design, construction techniques, elements, and systems are presented. Today, there is still a rich architectural heritage throughout the country, which has lasted through the years and withstood seismic activities and poor conservation.

Colorimetry of Clays as a Tool to Identify Soil Materials for Earthen Buildings Restoration

In the restoration field and the cultural heritage, the treatment of colour is very important, being an important factor for the decisions and interventions in historic buildings. However, some of these have not the same recognition and protection by authorities, being really vulnerable, especially against natural phenomena like the earthquakes. After the 2017 Puebla Earthquake, the remainders of the earthen architecture of Jojutla de Juarez were collected to be analysed. Natural clays of the quarries near the town were compared by colorimetry tests with the traditional adobe samples which were collected in the locality. There also were conducted particle size analysis and the Unified Soil Classification System, USCS, to obtain the composition and properties of the soils and the adobe bricks, as well as the additives used, mainly straw as fibre reinforcements of the adobe masonry. One of the factors observed which contributed to change the colorimetric values of the clays was the use of stabilizers like lime, on the other hand, these stabilizers also helped to change the USCS classification of the soils and their cohesive properties.

ANALYSIS AND CHARACTERISATION OF ADOBE BLOCKS IN JOJUTLA DE JUÁREZ, MÉXICO. SEISMIC VULNERABILITY AND LOSS OF THE EARTHEN ARCHITECTURE AFTER THE 2017 PUEBLA EARTHQUAKE

The 2017 Puebla Earthquake on 19 September struck a big part of central Mexico causing the loss of historic buildings in several states, being the state of Morelos one of the most damaged in the whole country. Jojutla de Juarez was the most affected locality of Morelos presenting important structural damages or total collapse in the built heritage, being the traditional earthen buildings, made of adobe bricks, the most vulnerable buildings to seismic efforts. Some of the causes which contributed to the poor behaviour of the buildings were the improper handling of the constructive systems and materials, the insufficient resistance of the structures and the problems with the foundations. The adobe houses of Jojutla presented a mixture between the traditional building techniques and industrial materials like concrete, cement and steel; also with irregular heights and plant layouts and inadequate connections between the walls and foundations and roofs, resulting into a higher seismic vulnerability when the earthquake impacted. Also the adobe bricks presented irregularities in its composition and use of additives which resulted in completely different typologies and the loss of the traditional construction techniques. A study was conducted to determine the properties of the remains of the adobe bricks of the houses in Jojutla, considering that the structures were severely damaged and a whole study of the seismic vulnerability would not be convenient due the loss of the physical traditional buildings. The grain size and composition of the adobe samples of the buildings were determined as well as the natural aggregates like straw, sand, and its proportion. A colorimetric study of the adobes and clays was also conducted, analysing the change of colour on account of the aggregates in the bricks. Also the compressive strength of the pieces was tested with two methods: the compression test and the point-load test, in order to obtain the indicative values which could be compared to other patrimonial and vernacular study cases.