Eco-friendly modification of earthen construction with carrageenan: Water durability and mechanical assessment

•Carrageenan bioadditives positively modified properties of earthen construction.•Increments in compressive strength of up to 85% were observed in admixture samples.•Tensile strength was increased up to 52% according to three-point bending tests.•Water repellence and erosion resistance were enhanced by using coating treatments.•Admixtures remained water resistant after 95days of environmental exposure. Carrageenan, a biodegradable natural polymer, was evaluated as a bioadditive to improve the physical and mechanical properties of adobe constructions. The results show that its incorporation in the mixture during blocks fabrication, or as a coating in existent earth constructions, positively modify their behavior providing water impermeability and resistance to erosion by water drops. Results of mechanical tests also show a considerable enhancement in compressive and tensile strength when the bioadditive is incorporated during the blocks fabrication process. The obtained results show the feasibility of using natural and eco-friendly compounds to modify the behavior of traditional construction materials.