Mechanical and thermal properties of cement mortar composites incorporating micronized miscanthus fibers

This study examines the impact of incorporating micronized miscanthus fibers into a cement mortar, focusing on the mechanical and thermal effects. Initially, an experimental procedure was devised to create mortar mixtures with varying amounts of miscanthus fibers, with a maximum dosage of 7 wt%. This involved saturating the fibers with water beforehand to maintain the workability of the fresh mixes. The resulting hardened bio- based mortars were then evaluated after 28 days in terms of their microstructure, me- chanical strength (assessed through flexural and compression tests), and thermophysical properties (measured using the Hot-Disk technique to determine thermal conductivity/ diffusivity and volumetric heat capacity). The experimental findings revealed significant enhancements (up to 87%) in the thermal resistance of the mortars due to the addition of fibers. However, this improvement was accompanied by a considerable reduction in me- chanical strength. As a result, while these bio-based mortars are unsuitable for structural applications, they still possess adequate mechanical properties for handling and are appropriate for insulation purposes in constructionANR-11-LABX-022-0

Mechanical and thermal properties of cement mortar composites incorporating micronized miscanthus fibers

This study examines the impact of incorporating micronized miscanthus fibers into a cement mortar, focusing on the mechanical and thermal effects. Initially, an experimental procedure was devised to create mortar mixtures with varying amounts of miscanthus fibers, with a maximum dosage of 7 wt%. This involved saturating the fibers with water beforehand to maintain the workability of the fresh mixes. The resulting hardened bio-based mortars were then evaluated after 28 days in terms of their microstructure, mechanical strength (assessed through flexural and compression tests), and thermophysical properties (measured using the Hot-Disk technique to determine thermal conductivity/diffusivity and volumetric heat capacity). The experimental findings revealed significant enhancements (up to 87%) in the thermal resistance of the mortars due to the addition of fibers. However, this improvement was accompanied by a considerable reduction in mechanical strength. As a result, while these bio-based mortars are unsuitable for structural applications, they still possess adequate mechanical properties for handling and are appropriate for insulation purposes in construction

Comparative Study of the Thermal Behaviors of a Cement Mortar Wall Including Bio-based Microencapsulated Phase Change Materials and a Reference Wall

International audienceThis study aims to evaluate the thermal behavior of a cement mortar wall (denoted M15D) including bio-based microencapsulated phase change materials (mPCMs) in comparison to a reference wall without mPCMs (M0). A bi-climatic test setup was designed and built in order to submit the two sides of the walls to different hygrothermal conditions representing the outdoor and indoor environments. Two scenarios were considered for the outdoor conditions: a cyclic solicitation of 12 h at 40 °C followed by 12 h at 15 °C to simulate a day/night variation, and a step change from 20 °C to 40 °C followed by prolonged exposure at 40 °C until steady-state, both at fixed relative humidity (50% RH). Temperature sensors installed at different depths made it possible to monitor temperature gradients within the walls during the tests. Overall, quite similar responses were collected for the two walls exposed to the same outdoor scenario. However, the maximum temperatures recorded on the external face and at several depth locations were slightly lower for the M15D wall compared to M0, with a gap of about 1 °C. This result suggests that the incorporation of mPCMs in the wall may contribute to dampen the effect of external temperature variations, although this action remains limited. Furthermore, this bio-based mPCM system offers an environmentally friendly alternative to traditional paraffinic mPCMs

Mechanical and hygrothermal properties of cement mortars including miscanthus fibers

International audienceThis study investigates the improvement of thermal and hygric performances of cement mortars through the introduction of micronized miscanthus fibers. Micronized fibers were chosen because they are expected to promote fine and homogeneous fiber distribution within the cementitious matrix, hence opening possibilities for the design of 3D printable mortar mixes including vegetal fibers. An experimental protocol was first developed for preparing five mortar mixes with miscanthus fiber contents up to 7 wt.%. These bio-based mortars were then characterized at the age of 28 days, in terms of mechanical strength (under flexural and compression tests), thermophysical properties (determination of the thermal conductivity/diffusivity and the volumetric Heat Capacity by the Hot-Disk method), and in terms of hygric properties as well (evaluation of the Moisture Buffer Value MBV according to the Nordtest method). The results of this experimental campaign showed that increasing the miscanthus fiber content leads to large improvements in both thermal resistance (up to 87%) and moisture buffer capacity of mortars (with MBV values up to 2.05), suggesting that such bio-based mortar is a good insulating material and has an excellent ability to mitigate external moisture variations. On the other hand, the introduction of vegetal fibers was also found to decrease very significantly the mechanical strength of the modified mortars, making these latter incompatibles with structural applications. Nevertheless, the developed bio-based mortars retain sufficient mechanical properties for handling and are suitable for building insulation

Mechanical and thermophysical properties of cement mortars including bio-based microencapsulated phase change materials

This study investigates the mechanical and thermophysical performance of cement mortars incorporating microencapsulated phase change materials (mPCMs), which consist of an aqueous dispersion of 100% bio-based fine core–shell particles. A specific protocol was used to manufacture the mortar samples, which ensures a homogeneous particle distribution and prevents microcapsule leakage. The addition of mPCMs to the mortar causes both a decrease in density, an increase in porosity, and a substantial loss of mechanical strength. Conversely, hot-disk characterization revealed a large improvement in the thermal performance. The system containing 8 wt% mPCMs exhibits a good balance between its mechanical and thermal properties