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This study aims to check the compatibility of a selection of waste and recycled biopolymers for rammed earth applications in order to replace the more common cement-based stabilization. Five formulations of stabilized rammed earth were prepared with different biopolymers: lignin sulfonate, tannin, sheep wool fibers, citrus pomace and grape-seed flour. The microstructure of the different formulations was characterized by investigating the interactions between earth and stabilizers through mercury intrusion porosimetry (MIP), nitrogen soprtion isotherm, powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The unconfined compressive strength (UCS) was also evaluated for all stabilized specimens. Three out of five biopolymers were considered suitable as rammed earth stabilizers. The use of wool increased the UCS by 6%, probably thanks to the combined effect of the length of the fibers and the roughness of their surfaces, which gives a contribution in binding clay particles higher than citrus and grape-seed flour. Lignin sulfonate and tannin increased the UCS by 38% and 13%, respectively, suggesting the additives' ability to fill pores, coat soil grains and form aggregates; this capability is confirmed by the reduction in the specific surface area and the pore volume in the nano- and micropore zones. [ABSTRACT FROM AUTHOR]

Bio-based materials with linear low density polyethylene (LLDPE) and a high content of thermoplastic starch (TPS) were prepared using the twin-screw extruder. The 25 μm thick films were blown with a Haake Polydrive internal mixer using a temperature profile with three zones: 160 °C, 170 °C and 165 °C. Morphology as well as thermal properties of the materials was investigated by field emission scanning electron microscopy (FE-SEM), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). As revealed by FE-SEM, a good dispersion of the TPS phase in LLDPE matrix was obtained. The DSC result confirmed the remarkable influence of TPS phase on crystallinity of LLDPE. Biodegradation of material in the form of film specimens were determined by weight loss, morphological surface change and mechanical properties. The results show more than 10% of the bio-film's weight is degraded after 5 months in the compost environment. [ABSTRACT FROM AUTHOR]

• Extended hygrothermal characterization of unstabilized rammed earth. • Low influence of density and grain size distribution on sorption isotherm. • High influence of density on thermal conductivity and vapor resistance factor. • Same linear dependency of thermal conductivity on moisture content for different soil compositions. • Vapor transfer resistance factor for a large span of relative humidity. Although hygrothermal properties of rammed earth represent great potential for improving thermal comfort during hot summers, still little knowledge is available about this topic. The literature lacks complete sets of hygrothermal characteristics of rammed earth, although they are fundamental for heat and moisture transfer modeling necessary to predict earthen building performances. The present work reports the results of a large collaboration between four academic laboratories in order to obtain an extended hygrothermal characterization of rammed earth, focusing on the material used in a modern construction in Lyon, France. The aim of the article is to provide for the same kind of soil an extend characterization on a large span of relative humidity to provide complete set of material properties for heat and moisture transfer simulation. The hygrothermal measurements cover adsorption and desorption isotherm, intermediate isotherm loop, specific heat capacity, dry thermal conductivity, moisture-dependent thermal conductivity and water vapor resistance factor for a large span of relative humidity. In addition, the capillary rise test was performed to estimate the liquid transport coefficient for suction and redistribution. The results show that variations in the density of the samples have a low impact on sorption isotherm, while they have a non-negligible impact on thermal conductivity and water vapor permeability. Surprisingly, variations in the grain size distribution do not produce a significant modification in the sorption isotherm, while hysteresis slightly reduces when bigger grains are added to the soil composition. Approximation of empirical model coefficients for the determination of moisture-dependent thermal conductivity is proposed for rammed earth materials. [ABSTRACT FROM AUTHOR]

In recent years, polymer clay nanocomposites have been attracting considerable interests in polymers science because of their advantages. There are many scientists who researched about this kind of material and demonstrated that when polymer matrix was added to little weight of clay, properties were enhanced considerably. Because clay is a hydrophilic substance so it is difficult to use as filler in polymer matrix having hydrophobic nature, so clay needs to be modified to become compatible with polymer. In this study, poly(ethylene oxide) was used as a new modifier for clay to replace some traditional ionic surfactants such as primary, secondary, tertiary, and quaternary alkyl ammonium or alkylphosphonium cations having the following disadvantages: disintegrate at high temperature, catalyze polymer degradation, andmake nanoproducts colorific, and so forth. In order to evaluate modifying effect of poly(ethylene oxide),modified clay products were characterize d by X-ray spectrum. Then organoclay was used to prepare nanocomposite based on unsaturated polyester. Morphology and properties of nanocomposites were measure d by Xray diffraction, transmission electron microscopy, tensile strength, and thermal stability. The results showed that clay galleries changed to intercalated state in the nanocomposites. Properties of nanocomposites were improved a lot when the loading of the organoclay was used at 1 phr. [ABSTRACT FROM AUTHOR]