Earth-Based Building Incorporating Sargassum muticum Seaweed: Mechanical and Hygrothermal Performances

Abstract

Once the tide recedes and leaves a significant amount of stranded seaweed on the coast, marine macroalgae pose a serious threat to the surrounding area. Through this work, we considered a large-scale application of stranded macroalgae in building construction. For the first time we studied the impact of incorporating Sargassum mitucum seaweed fiber in replacement of flax fiber used for a standard structural cob. Thus, cob specimens were elaborated and analyzed to evaluate their compressive and hygrothermal performances. It was found that the compressive strength and water vapor resistance factors of cob decreased with the algae content. Additionally, the obtained results showed that a cob made with Sargassum muticum algae presented better thermal (insulation and inertia) and hygroscopic properties than those of a cob made with a flax fiber. Indeed, the replacement of flax straw by algae lead to a reduction in the thermal conductivity by 38% when compared to the standard cob with 2.5% of flax straw fiber. Consequently, numerical simulation showed a reduction in the energy needs in buildings made with an algae-based cob when compared to those made with a flax-based cob. This study can contribute to a global environmental and economic issue, i.e., the valorization of brown algae on a large scale. Indeed, the worldwide knows the largest sea of sargassum algae extent measures over 8850 km2. This huge mass of brownish algae is expanding every year, which now covers an area from Africa to the Caribbean. It weighs more than 20 million tons and extends from the Gulf of Mexico to the west coast of Africa. We show that stranded algae, which are considered as wastes, have the ability to improve the mechanical and hygrothermal performance of cob-based material.

Advancing Earth-Based Construction: A Comprehensive Review of Stabilization and Reinforcement Techniques for Adobe and Compressed Earth Blocks

“…• Nine articles focused on powder: water hyacinth ash [44], sugarcane bagasse ash [7,35,45,46], and rice husk ash [47][48][49][50]; • Five articles focused on fibers: Pennisetum setaceum [51], plantain pseudo-stem fiber [52], coconut fiber [53], alfa fiber [54] and paper cellulose [55]; • Four items studied other types of waste: wheat and barley straw [27], sargassum muticum seaweed [31], crepidula fornicata seashells [56], and shea butter waste [57].…”

“…Some research efforts have focused on developing the thermal properties of lime-reinforced mud blocks [29], while others have evaluated the mechanical properties and durability of cement-stabilized earth blocks made from waste materials such as cassava wastewater [30]. Additionally, studies have explored organic binders of plant origin, such as research on sargassum muticum [31] or date palm fibers [32]. These studies focus on mechanical strength (compressive, tensile, flexural), hygrothermal parameters (thermal conductivity, heat capacity, dry density), and durability, as shown in Figure 2.…”

A Review—Durability, Mechanical and Hygrothermal Behavior of Building Materials Incorporating Biomass

“…Hemp and flax shives are more used, but the biobased used is not limited to these two types. Other materials such as kenaf, sisal, jute, flax, loofah, palm, and wheat are also used, and researchers have even explored the use of brown and red algae in this field [27].…”

“…➢ Brown seaweed in various forms (powder and fibers) is used in mixtures based on silty and clayey soils. The mechanical, thermal, and hydric properties have been studied in a mixture of brown seaweed (sargassum muticum) and loamy soil [27,76].…”

“…Seaweed is known for its hygrothermal properties. The presence of algae in an earthbased or cement-based mixture makes the mixture more thermally and water-insulating but mechanically weaker [27,76]. Figure 7 shows a type of brown seaweed: (a) material collected from the sea, (b) fiber after washing, (c) fiber after being dried for 24 h in an oven at 40 °C.…”