Raw earth-based building materials: An investigation on mechanical properties of Floridia soil-based adobes

Abstract

Raw earth, like wood and stone, is one of the oldest building materials used across the world. Nowadays, given the growing role of circular economy, researchers are ever more interested in raw earth-based building materials, because they are widely available and environmentally friendly. The use of this traditional material has positive environmental consequences, especially in traditional rural building reuse and in rural landscape preservation. In fact, raw earth is locally available and totally recyclable and, thanks to its perfect integration into the landscape, it improves site visual perception. Additives and/or chemical stabilizer agents (i.e., Portland cement) are often used in the production of raw earthbased building components in order to increase their mechanical performance and durability. This production process reduces the environmental sustainability of the base material and causes a relevant increase on the embodied energy (i.e., the total energy required for the extraction, processing, manufacturing, and delivery of building components). This research work aimed at investigating how to improve the mix-design of earth-based building materials in order to increase their mechanical properties without any addition of chemical agents. A physical stabilization was performed on an original texture soil by adding various particle sizes. Mechanical tests were carried out on five different soil mixes by changing soil composition, aggregates, and water. Specimens made with mix-design 5 offered the best results in terms of flexural and compressive strength values which were 1.65 MPa and 6.74 MPa, respectively. Mix 3 obtained the lowest linear shrinkage rate (6.04%). Since raw earth-based materials are highly sensitive to soil composition and aggregates, this study attempted to obtain a repeatable process to produce semi-industrial adobes by optimizing and controlling various natural materials (i.e., soils, aggregates, and water).

Reuse of livestock waste for the reinforcement of rammed-earth materials: investigation on mechanical performances

“…On a dry weight basis the rate was 45% of sand and 55% of FS M , the final design, including water, was 45% FS M , 35% sand, 20% water. In a previous work conducted by authors, this mix obtained the best mechanical performances among five different mix (Parlato et al, 2021). This characteristic sand called 'azolo' is formed on the surface of the lava by crushing glassy materials generated by rapid cooling of the magma.…”

“…Experimental tests were carried out on a soil mix previously investigated by authors (Parlato et al, 2021); this soil, chosen among five different soil design for its best performances, was embedded with raw sheep wool. The base material is composed of kaolinite soil called terra di Floridia (FS)…”

“…Several advantages come from the use of raw earth-based materials, all related to a significant decrease in environmental pollution and CO2 emissions. Raw earth building components, if made without chemical additives (i.e., only by physical and mechanical stabilization), are totally recyclable (Achenza and Sanna, 2009;Parlato et al, 2021). Generally, raw earth-based building components are extracted and worked directly or close to the building site, so their use significantly reduces logistic and transportation costs and the related gas emissions.…”

“…The design of the raw earth mix was prepared by performing only a physical stabilization, without the use of chemical additives, by obtaining a material that is totally recyclable at the end of its useful life (Parlato et al, 2021). The elements that we propose to develop could be used as closing elements.…”

Concrete Blocks Reinforced with Arundo donax Natural Fibers with Different Aspect Ratios for Application in Bioarchitecture

“…The effects of coconut fiber length and content on concrete properties were particularly analyzed by other authors [43], and the behavior of coconut fiber-reinforced building materials [44][45][46][47][48][49], for their use in a variety of applications, was also investigated [50][51][52][53]. Among the less common natural fibers used as reinforcement in building materials [54,55], we would definitely mention artichoke [56], okra [57], isora [58], ferula [59], althaea [60], piassava [61], sansevieria [62], and buriti [63].…”