Comparative moisture and heat sorption properties of fibre and shiv derived from hemp and flax

Abstract: Unlike many mineral-based insulation materials bio-based lignocellulosic fibre and shiv offer a number of benefits including thermal and hygroscopic properties. The microstructure, porosity and chemical compositions of the plant cell walls play a major role in the moisture exchange process. In this paper, the effects of microstructure, chemical composition, porosity and pore size distribution of both fibre and shiv, from hemp and flax plants, on both moisture and heat sorption were studied for the first time. The physical and chemical characteristics of the fibre and shiv from hemp and flax were studied by using scanning electron microscopy, mercury intrusion porosimetry and Fourier transform infrared spectroscopy. Water moisture sorption and heat of sorption were studied using a dynamic vapour sorption apparatus and a simultaneous thermal analysis system, combined with a humidity generator and using a copper furnace. Results showed that both the fibre and shiv of hemp and flax adsorbed a similar amount of moisture at a given relative humidity, which was dependent on the availability of hydroxyl groups for water in the cell wall. The macroscopic surface area and porosity of the specimen on a large scale had little influence on the availability of hydroxyl groups in the cell wall. The water molecules bound with cell wall molecules through hydrogen bonds over the full range of relative humidities, with a consistent hysteresis difference between the first sorption isotherm and subsequent sequential sorption cycles found in the hemp shiv specimens. For both hemp and flax, the isothermic hysteresis of the shiv was much higher than that of the fibre, which was shown to be dependent on the lignin content. The result of heat sorption indicated that some blocked sorption sites become available to water vapour molecules due to the change in molecular structure of the cell wall during the adsorption process. This study has improved understanding of the hemp and flax sorption behaviour and is important for optimal application of bio-based insulation materials for construction

Characterising the anisotropic nature of bio-composites

Buildings contribute substantially to our greenhouse gas emissions and energy demands both in their occupation and construction. Their construction also consumes large volumes of finite resources. Sustainable, low embodied energy, high performance crop based materials therefore offer great potential. Hemp-lime is a bio-composite concrete, mass infill material with a greatly lower embodied energy than equivalent traditional constructions. It also exhibits beneficial hygrothermal properties that can improve both a building’s energy performance and the comfort of its occupants by buffering humidity and temperature. It is however widely considered insufficient structurally, limiting its scope for application. A lack of understanding and acknowledgment that hemp-lime and other similar bio-composites are anisotropic, but instead have a directional internal structure, has hindered the development of stronger and more versatile products. In this work a range of methods based on digital image analysis and computer tomography were trialled with the aim of identifying the nature of hemp-lime’s internal structure and providing a methodology to classify it. The results from both digital imaging and computer tomography scanning indicate that the internal structure of the specimens considered was highly anisotropic; a strong directionality in the hemp particles was found to be induced by the construction process. The novel assessment methods developed to allow the numerical classification the internal structure that may be used in the future to allow the structural optimisation and modelling of bio-composites

Advanced Dynamic Vehicle Simulation

The Motorsports Engineering Program within the Purdue School of Engineering and Technology at Indiana University-Purdue University, Indianapolis (IUPUI) has partnered with Dallara Automobili to conduct basic and applied research involving dynamic vehicle simulation to advance motorsports engineering techniques and motorsports related economic development opportunities for the State of Indiana and beyond. The project includes completion and operation of the world’s most advanced vehicle dynamic simulator at Dallara’s IndyCar facility in Speedway, Indiana. This facility supports assembly of the racecars used for the IZOD IndyCar series, America’s foremost open-wheel racing series. The basic and applied research to be conducted by IUPUI using the advanced vehicle dynamic simulator at Dallara, includes the following aims: i) Correlation of empirical simulator data to both track-test empirical data and driver qualitative feedback; ii) Correlation of driver head and chest acceleration data between corresponding simulator and track-test situations; and iii) Extend simulator capabilities to other applications, including short track stock cars, sprint cars, etc., by developing new physics models to simulate appropriate track conditions

Moisture buffer potential of experimental wall assemblies incorporating formulated hemp-lime

Experiments were carried out according to the Nordtest protocol to study the moisture buffer potential of hemp-lime walls with a range of different internal linings and surface treatments. It was observed that the moisture buffer value was ‘Excellent’ when the inner surface of hemp-lime was exposed. ‘Excellent’ moisture buffer values were also obtained for hemp-lime with lime plaster. All other assemblies demonstrated ‘Good’ moisture buffer value. Moisture buffer values of the assemblies, after application of paint on the upper surfaces, were also determined. It was observed that application of synthetic pigment based trade paint could reduce the moisture buffer performance of the assembly consisting of hemp-lime and lime-plaster from ‘Excellent’ to ‘Good’ while between 61 and 69% reduction of moisture buffer value was observed for the other assemblies. However, the reduced buffer values of the assemblies are still comparable with other moisture buffering building materials. It was further observed that moisture buffer performance was improved when clay based organic paint was used instead of trade paint

Distillers Dried Grains Supplementation of Fall-calving Cows or Calves Grazing Stockpiled Forage During Winter (Progress Report)

Six 10-acre pastures containing Fawn endophyte-free tall fescue were strip-grazed by 4 pregnant fall-calving cows with calves from mid-November through March. Treatments applied to the cows in the six pastures included: Minimal supplementation (Minimal treatment), creep feeding a DDGS-soy hull pellet to calves (Creep treatment), or DDGS supplementation to cows (DDGS treatment). Cow weights and body condition scores and calf weights were measured over the winter grazing season. Over the season, calves in the Creep treatment had greater body weight gains than calves in the DDGS and Minimal treatments (3.1, 2.3, and 2.2 lbs/day, respectively). Partly because of a dry period while stockpiling forage and cold temperatures combined with snow and ice in late winter, cows in the Minimal and Creep treatments received 392 lb DDGS/cow over the grazing season compared to 948 lb DDGS/cow in DDGS treatment. As a result, there were no significant differences in cow BW or BCS between treatments throughout the winter grazing season. No significant differences were found in forage mass or the concentrations of CP, ADF, NDF, ADIN, or IVDMD of pasture samples collected before or during winter grazing between treatments. Results imply that creep feeding a corn-soy hull pellet will increase calf body weight gains. However, neither creep feeding calves nor supplementing DDGS to cows to maintain a condition score of 5 affects body weights or condition scores of cows grazing stockpiled forages in comparison to cows that are supplemented only when necessary because of excessive cold or ice

Hemp-Lime3:Highlighting room for improvement

Greenhouse Gas Emissions and growing energy demands are global issues that are exacerbated by the construction industry; an industry whose activities make up the majority of most country’s emissions, while the Housing Sector alone expends 60% of its total energy consumption on space heating of buildings [1]. Materials are continually being developed to be more environmentally friendly and reduce the carbon foot-print of buildings. Hemp-lime is a natural material that sequesters CO2 during growth of the hemp plant through photosynthesis; this reduces the material’s carbon footprint, allowing potential construction of ‘zero carbon’ buildings. The simple homogeneous construction of a hemp-lime building exhibits a good thermal performance, which can dampen fluctuations in external temperature and passively control internal humidity. This considerably reduces the demand on internal heating and cooling thus reducing the energy consumed within the building. Hemp-lime construction can be conducted in a number of ways including manual placement and spraying. This paper outlines some of the issues arising from differing construction methods, highlighting gaps in the knowledge and understanding of the use of this natural material. The paper concludes by presenting topics for further research in order to improve and promote hemp-lime use within the construction sector