Self-Compacted Clay based Concrete (SCCC): proof-of-concept

Construction using mineral soil is gaining interest in developed countries, whereas this practice is common in Africa and was more common in Europe 200 years ago. The forecasted increasing demand for cement in emerging countries has created the need for alternative building materials. In this study, recent cement and concrete technologies are transferred to earthen constructions to create a Self Compacted Clay Concrete. We showed that the use of a superplasticizer with mineral soil alone reduced the yield stress and was more efficient when cement was added. The optimal rheology was reached with 1% polycarboxylate ethers superplastizer and 5% calcium sulfoaluminate cement (CSA). The setting was studied with a digital penetrometer. The accelerated phase of the CSA hydration occurred within 6 h only when 5% of CSA was in the earth mixture. Cement transformed the interstitial liquid water between particles into chemically bound water that did not affect the flow in the fresh state. Mechanical tests on the dried self-compacting-clay concrete showed that the compressive strength was increased by a factor of four when reducing the initial water content. The compressive strength of earth material is known to vary with the dry density and the clay minerals content in the compressed earth block. The novelty of our approach is that the identical results can be achieved with a material poured in a formwork rather than compacted. Finally, the carbon footprint of the solution was evaluated, and the results show that this new material is competitive with current construction techniques. Crown Copyright (C) 2016 Published by Elsevier Ltd. All rights reserved.