Beyond efficiency: Engineering a sustainable low-tech cementitious binder for earth-based construction

Abstract

The low environmental impact of earth – or soil – materials makes them interesting alternatives to lower CO2 emissions from the construction sector. Nevertheless, since they are often stabilized with Portland cement, the improvements in technical performance come at an environmental cost. In this paper, we revisit a vernacular stabilization technique to formulate a trass-gypsum-lime binder aiming at increasing strength and reducing environmental impact. To do so, we tailor the binder reaction product assemblage and make use of local low-footprint raw materials. The increase in the trass content in the binder – at the expense of the content of gypsum hemihydrate – resulted in improved hydrated phase assemblage, i.e., ettringite, C-A-S-H, higher compressive strength, and lower carbon footprint. An additional strength gain was obtained by adding a low sucrose dosage to the binder, which ultimately resulted in an optimized strength/impact relation. This approach offers a new perspective on the engineering of binders for earth-based construction.