An Experimental Study on Earthen Materials Stabilized by Geopolymer

Earth is an ancient building material which has been recently the focus of scientific research due to its sustainable properties. The disadvantage of earthen material is its low strength and its sensibility to the water content. To enhance the durability and the mechanical characteristics of earthen material, hydraulic binders are currently added (cement or lime) which have high embodied energy and therefore increase the embodied energy of the stabilized earth material. This paper presents an exploratory study which uses geopolymer as a stabilizer for earthen material. Geopolymers are inorganic binders with polymeric structure obtained by alkaline activation of raw materials containing silicon and aluminum; they are obtained by dissolution/precipitation reactions at low temperature. The present study proposes to use blast furnace slag as geopolymer raw material, which was mixed with an alkaline solution activator to obtain the stabilizer for earthen material. The geopolymer effects were investigated on two types of earthen material: rammed-earth (RE, soil dynamically compacted) and soil-geopolymer-concrete (soil poured with more water content). The results show that geopolymer had more effects in soil-concrete than in rammed-earth. Indeed, RE specimens stabilized by geopolymer did not present a significant improvement of compressive strength comparing to the unstabilized RE specimens. Soil-geopolymer-concrete specimens had double compressive strength comparing to soil-cement-concrete specimens.