Particle Size and Plant Fibre Effects on Adobe Durability Under Wetting-Drying and Accelerated Weathering

[EN] Adobe construction, as part of earthen architecture, is a traditional building technique that is widely used but particularly vulnerable to the effects of water and other climatic factors. This article analyses the physical and mechanical behaviour of three different grain sizes of adobe specimens, classified according to the predominant presence of coarse aggregates (CA), fine aggregates (FA), and fine aggregates with plant fibres (AF). In order to assess their response to climatic scenarios, these specimens are subjected to wetting¿drying cycles (3, 5, and 7 cycles) and accelerated weathering tests (E) under controlled laboratory conditions. The main objective is to determine the influence of particle size distribution and the incorporation of plant fibres on the strength, stiffness, durability, and hydraulic behaviour of the material. For this purpose, an experimental programme was developed based on compression, modulus of elasticity, ultrasonic, abrasion, hydraulic erosion, and capillary absorption tests, and carried out at different stages of deterioration. Thus, six specimens were analysed for each of the five time points studied (0, 3, 5, 7, E) and for each proposed particle size distributions, giving a total of 450 samples analysed. The results show that the coarse mix exhibits greater overall mechanical stability, whereas the fine mix is more sensitive to the action of water. Although the addition of fibres improves ductility and resistance to surface erosion, it alters the porous structure of the material. Overall, the results confirm that particle size distribution and fibre reinforcement decisively influence the durability of adobe.