Hygrothermal and microstructural characterization of self-consolidating earth concrete (SCEC)

Abstract

The incorporation of earth-based materials offers the construction industry superior hygrothermal performance, hence ensuring significant ecological and environmental benefits. The hygrothermal and microstructural characteristics of self-consolidating earth concrete (SCEC) are investigated in this study. These traits include the sorption isotherm, permeability, heat capacity, thermal parameters (conductivity, diffusivity, and effusivity), moisture buffer value (MBV), total porosity, pores distribution, and microstructural characteristics. The sorption isotherm tests revealed that the investigated SCEC mixtures gained lower water content (around half) compared with the reference self-consolidating concrete (SCC) mixture (1.5% vs. 3.3% at 90% relative humidity). These results are comparable to those reported for clay bricks in the literature. The SCEC mixtures also showed higher permeability due to their higher porosity and connected pores. Thermal conductivity, diffusivity, and effusivity of the investigated SCEC mixtures showed lower values than those of the reference mixture. At 10 °C, the investigated SCEC mixtures exhibited lower thermal conductivity values of 0.400–0.500 W m−1 K−1 compared with those of the reference mixture (0.765 W m−1 K−1). Since the diffusivity and effusivity of the earthen materials are higher than those of wood, SCEC mixtures can offer both low diffusivity and high effusivity among different construction materials. Furthermore, the investigated SCEC mixtures exhibited lower mass losses attributed to calcium silicate hydrate (CSH), dehydroxylation of portlandite, and decarbonation than the reference mixture. The water vapor and gas permeability of SCEC were in good agreement with cumulative pore volume in the ranges of 100–200 nm and 100–300 nm, respectively. On the other hand, the drying shrinkage and compressive strength values were dependent on the cumulative pore volume of pore sizes less than 1 μm.