Self-Compacting Earth-Based Composites: Mixture Design and Multi-Performance Characterisation

Abstract

A new generation of self-compacting earth-based composites (SCEC) for vertical elements with fully exposed earth, in which the main feature is the elimination of compaction, is proposed in the current work. The first objective was to develop earth-based mixture compositions with locally available raw materials and achieve self-compactability. A Portuguese soil, typically employed in rammed earth construction, was stabilised using cementitious materials and a superplasticiser to ensure flowability. The mixture design studies allowed to achieve flowable fresh composites. Results on the hardened state showed that SCEC presents high compressive strengths (5–14 MPa). The electrical resistivity SCEC increased with time and achieved at least 5600 Ωm at 28 days, while mass loss stabilised after 14 days in a controlled environment room. Additional tests were performed on selected optimal SCEC mixtures: drying shrinkage and water capillary absorption, with promising results. Overall, this work provided initial boundaries for the mixture design and assessment of SCEC and opened the door for further studies on new and novel earth materials construction techniques.