A new procedure to adapt any type of soil for the consolidation and construction of earthen structures: projected earth system

Abstract

ABSTRACT:The "projected earth system" is put forward as an alternative construction method. The soil from each site is adapted following a specific protocol to make it suitable for spraying. The type of construction and the receiving surface determine the machinery and spraying system used (dry or wet mix). The result will be similar in texture and colour to the original material (in the case of earth walls) or to the surrounding material. RESUMEN:Un procedimiento nuevo para adaptar cualquier tipo de suelo para la construcción y consolidación de estructuras de tierra: Sistema de Tierra Proyectada. Se plantea la "tierra proyectada" como nuevo sistema constructivo. Se adecuará la tierra de cada intervención con un protocolo para poder ser proyectada. El tipo de intervención y el soporte sobre el que se proyectará determinarán la maquinaria y el sistema de proyección (vía seca o húmeda). El resultado tendrá similar textura y color que el soporte restaurado (en muros de tierra) o que el material del entorno (en taludes carreteros u obras de tierra de nueva construcción).

Earth as a Sustainable Construction Material. Characterization of Different Mixtures and Implementation Using the Projected Earth System

“…Both size distribution and Atterberg limits establish an SM or SC-SM classification [1] with different percentages of gravel for the soil used. If we compare with the results in samples from level 2 of the "Alhambra Formation" [15], which corresponds to the parental sample of this edaphic soil, the lack of fines in the soil of this investigation is corroborated, since that we lack samples classified as SC, as well as the significant presence of coarse (gravel) that at the aforementioned level provides GC and GC-GM classifications. Therefore, the edaphic soil in question differs fundamentally from its parent soil in that the clay content is very low, and the coarse sizes are also poorly represented.…”

“…The carbonate content varies between 15.50 and 32.50%, resulting in a characteristic average value of 22%, taking into account that two of the dominant components of the soil are carbonates (calcite, dolomite), which explains why the highest values are found between 5 and 16 mm where calcite and dolomite grains should be especially concentrated, also, in the finest particles of this level (0.16-0.18 mm), the carbonate content is also elevated, which is quite normal in the B horizon of edaphic soils due to the washing out of salts in the upper horizon. Compared to Alhambra Formation (level 2), carbonates range between 13.5 and 17.1%, essentially concentrated in fines [15].…”

“…These are colluvial sediments that make up the Alhambra Formation, characterized by its reddish color. All the results of the study of the physical-mechanical properties of edaphic soils will be compared with those obtained for the Alhambra Formation which is used in many of the surviving rammed earth constructions in the city of Granada (Spain), including fortifications, dwellings, and walls [15].…”

Multi-Criteria Parametric Verifications for Stability Diagnosis of Rammed-Earth Historic Urban Ramparts Working as Retaining Walls

“…Regarding sliding and bearing failures, the determining factor is the ground resistance. The verification of such limit states, both with EC7-1 and CTE DB SE-C, is given by Equation (4), where E d is the design effect of actions and R d is the corresponding design resistance.…”

“…In these cases, there are different ways of solving the problem, which usually take into account, among other things, the restitution of the lost material not to compromise stability. In the restoration of several walls in the Generalife of the Alhambra in Granada, an innovative technique of soil projection was applied, in order to restore the lost part of the section because of the water seepage from the backfill [4]. In any case, stability verifications should be performed after any changes have been in use and also whenever the section of the wall is changed.…”