Shives Research Articles

Influence of compactness and hemp hurd characteristics on the mechanical properties of lime and hemp concrete

Influence of compactness and hemp hurd characteristics on the mechanical properties of lime and hemp concrete

Influence of compactness and hemp hurd characteristics on the mechanical properties of lime and hemp concrete

ABSTRACT Research on concrete made with hemp is part of a sustainable development policy in the building field. The very low apparent density of the hemp hurds confers to lime and hemp concrete lightness and low thermal conductivity, however compared to usual construction materials, it has low mechanical strength. The presence of fibres in the hemp, the optimization of the granular to binder ratio, and the compaction during the casting process represent parameters which could significantly increase the compressive strength and change the mechanical behaviour of the material. A brief study of these parameters is presented and discussed in this paper.

Mechanical properties of lime–hemp concrete containing shives and fibres

The effect of using different binding agents in combination with hemp shives and fibres in Lime-Hemp Concrete (LHC) building material was examined. LHC is a light composite building material with building lime as binding agents and hemp (Cannabis sativa) as a renewable raw material from agriculture. Contemporary LHC only uses the woody core part of the hemp, the shive. However, using both hemp shives and fibres may improve the mechanical strength, eliminating the need for a fibre separation process. The aim was to elucidate the feasibility of using the entire fragmented hemp stalk in an LHC, and to determine some important material properties such as compressive strength, splitting tensile strength, water sorption and frost resistance. LHC with varying inclusions of the lime-based binders were tested, as were five mixes using the binding agents hydrated lime, hydraulic lime, and cement. Specimens were cured for 12 weeks at room temperature and 40 days in a carbonation room (4.5 vol% CO2), and tested for mechanical properties, water sorption and frost resistance. Using both shives and fibres in LHC may be advantageous for countries such as Sweden where facilities for separating hemp from shives are not commercially available. (C) 2009 IAgrE. Published by Elsevier Ltd. All rights reserved. (Less)

Efficient Sugar Release by the Cellulose Solvent-Based Lignocellulose Fractionation Technology and Enzymatic Cellulose Hydrolysis

Efficient liberation of fermentable soluble sugars from lignocellulosic biomass waste not only decreases solid waste handling but also produces value-added biofuels and biobased products. Industrial hemp, a special economic crop, is cultivated for its high-quality fibers and high-value seed oil, but its hollow stalk cords (hurds) are a cellulosic waste. The cellulose-solvent-based lignocellulose fractionation (CSLF) technology has been developed to separate lignocellulose components under modest reaction conditions (Zhang, Y.-H. P.; Ding, S.-Y.; Mielenz, J. R.; Elander, R.; Laser, M.; Himmel, M.; McMillan, J. D.; Lynd, L. R. Biotechnol. Bioeng. 2007, 97 (2), 214- 223). Three pretreatment conditions (acid concentration, reaction temperature, and reaction time) were investigated to treat industrial hemp hurds for a maximal sugar release: a combinatorial result of a maximal retention of solid cellulose and a maximal enzymatic cellulose hydrolysis. At the best treatment condition (84.0% H3PO4 at 50 degrees C for 60 min), the glucan digestibility was 96% at hour 24 at a cellulase loading of 15 filter paper units of cellulase per gram of glucan. The scanning electron microscopic images were presented for the CSLF-pretreated biomass for the first time, suggesting that CSLF can completely destruct the plant cell-wall structure, in a good agreement with the highest enzymatic cellulose digestibility and fastest hydrolysis rate. It was found that phosphoric acid only above a critical concentration (83%) with a sufficient reaction time can efficiently disrupt recalcitrant lignocellulose structures.

Generation of Airborne Particles from Different Bedding Materials Used for Horse Keeping

Among other factors (eg, feed), bedding material has an important effect on stable air quality with respect to airborne particle formation. This study was designed to establish which material is suited to create an improved stable environment for horses. First, the following materials were analyzed under standardized conditions in a laboratory experiment: wheat straw, dry wood shavings, hemp shives, linen shives, wheat straw pellets, paper cuttings (unprinted newspaper). The second investigation was carried out under in situ conditions in which three of these bedding materials (wheat straw, wood shavings, and straw pellets) were analyzed under practical conditions. In both experiments, airborne particle concentrations were detected online with the gravimetrically measuring analyzer TEOM 1400a (Rupprecht & Patashnick Co., Franklin, MA). In the laboratory experiment, the TEOM was equipped successively with different inlets to measure the particle fractions PM 1, PM 2.5, PM 10, and PM 20. During the in situ experiment, only the fraction PM 10 was detected. In the laboratory experiment, hemp and linen had the highest generation of airborne particles in all fractions. The lowest particle generation was detected with straw pellets. Results of the in situ investigation supported results of the laboratory experiment with respect to mean particle generation of straw pellets. With an average of 111.2 ± 149.2 μg/m 3, it was significantly lower than the mean particle generation of wheat straw with 227.5 ± 280.8 μg/m 3. The particle generation of wood shavings had an average of 140.9 ± 141.9 μg/m 3 and also was significantly lower than the generation by wheat straw. An activity-correlated variation of particle concentrations was found. In conclusion, taking both experiments into consideration, straw pellets seemed to be suitable for horse stables, to promote an improvement in the stable climate in relation to airborne particle formation.

Evaluation of Factors Influencing the Generation of Ammonia in Different Bedding Materials Used for Horse Keeping

Bedding material is an important factor in determining stable air quality in terms of ammonia formation. The objective of this study was to analyze different bedding materials used for horse stables under standardized conditions, to determine which material is best suited for improving the climate of a stable. The particular concern was a reduction in gaseous ammonia concentrations. Therefore, the following materials were examined: wheat straw, wood shavings, hemp shives, linen shives, wheat straw pellets, and paper cuttings. Twelve containers were constructed in an environmentally controlled room, and the same material was placed into two containers, with the amount of material used being determined by its carbon content. A defined ratio of horse manure/urine mixture was added daily to each container over a period of 14 days. The concentrations of gaseous ammonia, carbon dioxide, nitrous oxide, and water vapor were measured continuously above the bedding within the containers. Means of gaseous ammonia were found to be 178.0 mg/m 3 for wheat straw, 155.2 mg/m 3 for wood shavings, 144.6 mg/m 3 for hemp, 133.7 mg/m 3 for linen, 60.3 mg/m 3 for straw pellets, and 162.6 mg/m 3 for paper cuttings. In conclusion, the results of this study have shown that straw pellets are suitable for horse stables, not only to improve air quality but also, first and foremost, in relation to ammonia binding and ammonia transformation within the bedding material, respectively. However, straw pellets may also have disadvantages. The high substrate temperatures that were measured in straw pellets could favor the growth of pathologic germs that can adversely affect animals' health.

Mechanical and thermal properties of lime and hemp concrete (“hempcrete”) manufactured by a projection process

Concrete blocks, made of a mixture of lime and hemp shives (also called “hemp hurds”), have been manufactured by a recently developed projection process. Lime carbonatation kinetics is determined by X-ray diffraction. Density measurements are made within blocks, and thermal and mechanical properties are measured (flexural strength, compression strength and hardness). The main observations are moderate density variations within a given block, and an influence of the projection distance on density. Both thermal conductivity and mechanical properties increase with the mortar density, which is well described by existing theoretical models. Compression tests induce a compaction, or densification, of the material.

Official Founding of the “European Industrial Hemp Association (EIHA)” and Third International Hemp Conference

Abstract On 23 November 2005, the “European Industrial Hemp Association” was officially founded. For the next year, the EIHA has planned the setup of a system that shall supply studies and background information on hemp via the Internet as well as an overview study of the ecobalances for hemp products that have been conducted so far. On 28 and 29 November 2005, the third International EIHA Conference brought together 70 experts from 15 countries. The spectrum of participants ranged from cultivation, consulting, primary and further processing, trade, mechanical engineering and investors to numerous small — and medium-sized enterprises and to globally operating automotive enterprises and suppliers. They all had in common the fact that they were interested in the utilisation of hemp fibres and shives.

Hemp for Victory Era Salesman's Kit

Abstract The author has discovered an intact collection of World War II era hemp samples that document the state of the North American hemp industry before it was shut down at the end of the Hemp for Victory Campaign in 1945. Included in one box are samples of various grades of hemp straw and hemp fiber. The second box contains sales samples of hemp and hemp-blend yarns and threads. It also contains samples of finished textiles, hemp hurds and seeds and other miscellaneous items. The collection offers a wide range of research possibilities.

European hemp industry: Cultivation, processing and product lines

Two fibre plants are under cultivation in the European Union – flax on approximately 125,000 ha and hemp on approximately 15,500 ha in the year 2004. Seeds, hurds and especially fibres of hemp are used for further processing. The most important markets for hemp fibres produced in the EU are pulp and paper and the automotive industry. Just under 5% of the EU hemp fibres were used in the construction sector. Approximately 95% the whole production of 40,000 t of the hemp hurds are used as animal bedding and 95% of the estimated 6000 t per year hemp seeds are sold for animal feed, mainly as bird feed.