Design of Tannin-Based Poured Earth Material via Deflocculation-Coagulation Control: Additive Selection and Tannin Variation

Combining the low environmental impact of vernacular earthen construction and the cost efficiency of the modern concrete pouring technique, poured earth is becoming more attractive for the construction sector nowadays. However, the development of poured earth is still in its infancy and few design options have been reported. In this study, we present a new type of poured earth based on natural tannin extracts and iron compounds. Tannin is used as a dispersant to liquefy clay materials, while the iron compound acts as an antitannin agent to slowly remove the dispersing effect and recoagulate clay. Specifically, iron compounds with different solubilities were selected and their complexation reaction kinetics with oak tannin were investigated through various techniques including UV-vis, ATR, o, and rheological measurements. Iron citrate was finally screened out because of its controlled speed of chelating tannin originating from various species with and without the presence of kaolinite. Such a study enables the production of a poured earth material based on natural additives with higher strength and water resistance. It paves the way for locally tailored solutions for circular and climate-neutral construction.

Automated summary

The study explores the use of natural tannin extracts and iron compounds to create poured earth material with higher strength and water resistance, paving the way for locally tailored solutions for circular and climate-neutral construction.