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There is a growing interest in straw bale construction for its low embodied energy and insulation value. Early studies of its structural behaviour and fire resistance have shown it to be a viable alternative to traditional building techniques. However, the biggest remaining obstacle to widespread acceptance is the moisture behaviour within the straw bale walls, especially as it concerns mould growth. The uncertainty of this behaviour leads to the hesitation of building officials and insurance providers to freely accept straw bale construction. Therefore, this study investigates the moisture, temperature and mould growth in straw bale walls, through a combination of analysis, dynamic modeling and field studies. A study of mould is presented along with the current methods available for predicting mould growth. Moisture is the primary controllable factor to mould growth in buildings. Therefore, an understanding of moisture accumulation within straw bale walls is necessary to provide a safe design that precludes mould growth. This study compiles the current state of knowledge of the hygrothermal properties of the materials used in straw bale walls. Then a parametric steady-state analysis is conducted to show the expected behaviour of vapour diffusion and the effects of the material properties. Two 14”thick x 6’ wide x 8’ high straw bale test walls were constructed: one was rendered with a typical cement-lime plaster and the other with a clay plaster. Temperature and moisture were monitored throughout the walls for over a year. These test walls provide more information on the macro behaviour of the walls to both vapour diffusion and, more importantly, rain. Hygrothermal computer modeling was conducted and compared to the test data to assess its accuracy. Thermal modeling was successful, while moisture modeling was found to be more difficult due to a lack of accurate rain data. With better climate data it is expected that accurate hygrothermal modeling of straw bale walls is possible. The result of this work is a general starting point for more detailed studies of the hygrothermal behaviour of straw bale walls with the ultimate goal of assessing the mould risk for various construction techniques and locations.

The search for more sustainable construction methods has created a renewed interest in straw bales technology. Straw bales are a composite material that is energy efficient and durable. Rectangular straw bales stacked in a running bond and plastered on the interior and exterior faces have adequate strength to resist typical loads found in two-storey structures. The structural behaviour of a load-bearing plastered straw bale wall subject to uniform loading is well researched. However, door and window voids in the wall redistribute vertical load paths and produce areas of concentrated stress. This thesis describes experiments on small-scale plastered straw bale panels subjected to loading conditions that simulate the loading conditions experienced in areas around door and window voids. Twenty-one specimens were tested under two main types of loading conditions. The specimens were rendered with lime-cement plaster, were one to three bales (0.33 m to 0.99 m) in height, and were either unreinforced, or contained metal diamond lath or chicken wire embedded within the plaster. The specimens were pin-supported at various centre-to-centre distances ranging from 200 mm to 500 mm and were loaded either uniformly or by a point load. Two distinct types of failure were observed. Strut-and-tie models were developed to describe the structural behaviour of panels undergoing vertical cracking of the plaster skin at failure. Bearing models were developed to describe the structural behaviour of panels undergoing crushing of the plaster skin beneath the point of applied load. The models predicted the correct failure mode of 92% of the specimens and had an average ratio of experimental strength to theoretical strength of 0.95 with a standard deviation of 0.17. The results show that the behaviour of plastered straw bale walls can be predicted using common methods of structural analysis. A parametric analysis of door and window voids within plastered straw bale walls is presented. / Thesis (Master, Civil Engineering) -- Queen's University, 2010-09-30 11:32:53.613

The performance of plastered straw bale walls with respect to wind-driven rainfall was investigated in this thesis. The absorption coefficient, which describes the rate of water infiltration, was measured for 14 plaster types, twelve different earth plasters and cement and lime plasters. The absorption coefficient was measured during uptake of water from a free reservoir. The effective porosity of these plasters, which describes the moisture storage capacity and the degree of protection that a plaster offers to straw bales, was also determined by submersion in water. An analytical model employing the absorption coefficient, the effective porosity, and climatic data was used to predict and compare plaster performance and to demonstrate the usefulness of this type of data. Simulated wind-driven rainfall experiments were also conducted on two plaster types. The results indicate that the static test used to measure the absorption coefficient can reasonably be used to predict actual wind-driven rainfall infiltration.

Tyrimo tikslas – suprojektuoti šiaudų paruošimo įrenginį. Bakalauro baigiamojo darbo pirmoje dalyje išanalizuoti pagrindiniai šiaudų paruošimo įrenginio techniniai – ekonominiai rodikliai.Antroje darbo dalyje aprašyta gaminio paskirtis ir panaudojimo galimybės bei alternatyvos, išnagrinėti šiaudų paruošimo įrenginį sudarantys elementai: mazgai, mechanizmai. Atlikta šiaudų paruošimo įrenginio mazgų konstrukcijos variantų apžvalga – korpuso, būgno, pavarų mazgai, standartinių gaminių, konstrukcinių sprendimų palyginimas. Atlikti gaminio techniniai skaičiavimai (šiaudų paruošimo įrenginio pavaros kinematiniai skaičiavimai, šiaudų paruošimo įrenginio sukamųjų būgnų techniniai skaičiavimai, bei reikalingas kiekis šiaudų rulonų pasirinktai galiai išgauti, įrenginio kėlimo ąsos apkrovos leistinų įtempių skaičiavimas). Trečioje darbo dalyje išanalizuota trijų detalių technologiškumas. Parinkti detalėms ruošiniai, sudaryti technologiniai maršrutai, nustatyti apdirbimo operacijoms reikalingi įrengimai, apskaičiuotas jų kiekis. Atliktas užlaidų, pjovimo režimų nustatymas bei techninis normavimas.Ketvirtoje darbo dalyje pateikiama įmonių ir aplinkos saugos reikalavimai eksploatuojant įrenginį, jo ergonomiškumas ir įtaka aplinkai. Penktoje darbo dalyje atlikti ekonominiai skaičiavimai, kurių pagalba nustatyta ir pagrįsta šiaudų paruošimo įrenginio savikaina. / Research aim – to design a straw preparation equipment. In the bachelor's work first part there are analysis of the main straw preparation equipment technical-economic indicators.The second part describes the purpose and use of product options and alternatives, examines straw preparation equipment compilling elements: knots, mechanisms. Was made a straw preparation equipment knots construction options review - corps, drum, gear knots, standard products, comparison of construcion solutions. Was performed technical calculations of the product (straw preparation equipment gear‘s kinematic calculations, rotary drum technical calculations, and the required amount of straw rolls for the desired power extraction, equipment lifting eyelet load allowed stress calculation). The third part analyzed three parts fabrication. Were selected blank parts, created technological routes, determinated equipment necessary for manufacturing operations, calculated it‘s amount. Determinated an overlap, cutting mode setting and the technical rationing. The fourth part of the work presents companies and environmental safety requirements for maitaining the device, it‘s ergonomic and impact to environment. In the fifth bachelor‘s work part there are economic calculations, which assistance was determined and substantiated straw preparation equipment prime cost.

The performance of plastered straw bale walls with respect to wind-driven rainfall was investigated in this thesis. The absorption coefficient, which describes the rate of water infiltration, was measured for 14 plaster types, twelve different earth plasters and cement and lime plasters. The absorption coefficient was measured during uptake of water from a free reservoir. The effective porosity of these plasters, which describes the moisture storage capacity and the degree of protection that a plaster offers to straw bales, was also determined by submersion in water. An analytical model employing the absorption coefficient, the effective porosity, and climatic data was used to predict and compare plaster performance and to demonstrate the usefulness of this type of data. Simulated wind-driven rainfall experiments were also conducted on two plaster types. The results indicate that the static test used to measure the absorption coefficient can reasonably be used to predict actual wind-driven rainfall infiltration.

Polypropylene continues to be the mainstream choice thermoplastic for automotive applications. In many applications PP is filled with mineral fillers for improvement of properties. Biobased natural fillers or fibres are attractive materials to reduce the weight because of the low specific gravity of the biobased materials compared to the mineral fillers. Our group has done extensive research on the development of wheat straw fiber in thermoplastics in the past years. It is very important to understand the behaviour of single fillers on composites before studying the effects of mixing fillers or fibers (hybridization). The objective of this study is to evaluate and compare systematically the effects of wheat straw and mineral fillers in the polypropylene matrix. The study includes two types of wheat straw (WS) categorized based on their size (fine WS and medium WS) and three different types of natural minerals (Talc, Mica and Wollastonite). Three types of polypropylene (PP), Homopolymer PP, High Impact Copolymer PP and Homopolymer-Copolymer Blend PP, were investigated as the matrix. This study also evaluates the effect of combining two fillers (WS and mineral filler) in the hybrid composite. The fillers were formulated in three different percentages (20, 30 and 40wt %) and compounded via extrusion. Samples for all formulations were prepared by injection molding. The mechanical properties (flexural modulus and strength, tensile modulus and strength, impact strength), water absorption and density were measured. The properties of hybrid composites were evaluated by varying the amounts of two fillers at 10wt%-20wt%, 15wt%-15wt% and 20wt%-10wt% each, keeping the overall filler content constant at 30wt%. The effect of type of filler, filler size and filler content were critical in this work. The results obtained from this study indicated that filler type and filler content greatly influenced the mechanical properties and water absorption characteristics of the composites. The flexural modulus increased with increasing filler content. It was interesting to observe that though the impact strength decreased with the addition of fillers, increasing the filler content from 20 to 40 wt% did not affect the property. With respect to all fillers, wollastonite improved the mechanical properties significantly. Increasing the amount of WS content reduced the composite’s resistance to water absorption. Among mineral fillers, mica showed significantly higher percentage gain in weight with water absorption. Combination of fillers at varying percentages did not have any synergy effect on the mechanical behaviour of the composite. The percentage increase in weight with water absorption was observed to be increasing with increasing WS content in hybrid composites, but significantly lower than pure WS composites. The morphological study on WS composites revealed improved interaction of filler with homopolymer and polypropylene blend.

The use of wheat straw and other agricultural by-product fibers in polymer composite materials offers many economical and environmental benefits. Wheat straw has been recently commercialized as new filler for polypropylene thermoplastic composites in automotive applications. However, to expand its application in the automotive industry and other sectors where highly-engineered materials are needed, a systematic database and reliable composite property models are needed. For this purpose, this research was systematically conducted. A product design approach is used in studying wheat straw polypropylene (WS-PP) composite. A set of thermoplastic composite specifications relevant to several automotive parts was used as a basis for the customer needs which give the direction to the entire product design of thermoplastic composites based on polypropylene and straw. Straw fibers were produced by grinding and sieving (without any other treatment). These fibers were used in the formulation of polypropylene thermoplastic composites to understand the variable that can contribute to minimize production cost, maximize product performance and maximize wheat straw utilization (fraction of renewable material). The variation in chemical composition due to plant variety (parts of the plant, location of harvesting and seasonality), the bonding incompatibility between hydrophobic polypropylene matrix and hydrophilic straw fiber, along with the heterogeneity of fiber size and shape, has made wheat straw polypropylene composite a complex system. This complexity causes the mechanistic approach of composite modeling in the well-established composite theory difficult to be applied, since modeling the contribution of natural fibers to the performance of thermoplastic composites is not as straightforward like in the case of homogenous glass fiber (with same shape, diameter and narrow length distribution). Alternatively, a statistical approach of modeling by using designed experiments was used in this research. The Mixture and Process-Mixture Experimental Design methodologies were applied to develop response surface models that can be used to correlate input properties and formulation of these thermoplastic composites to the final properties of the product. The models obtained can then be inverted to predict the required properties and formulations using fiber (straw), matrix (polypropylene), and additives (coupling agent) as the main components for a specified product performance. The prediction includes the fiber grading (size and aspect ratio) and classification in order to maximize fiber utilization for different needs of composite products. The experiments were designed based on the analysis of the existing data provided by previous research works of wheat straw polypropylene composite system in our laboratory and by experimental data generated during this research. The focus of the analysis was the determination of the factor(s), i.e., the independent variables of the experiments and their acceptable levels. The response variables being measured were chosen based on the required specifications of targeted products. A constrained three-component mixture design of experiment was conducted to develop models for flexural properties of WS-PP composite. The three independent mixture variables in this experiment were the weight proportions of: straw (as fiber), polypropylene (as matrix), and maleic anhydride polypropylene (as coupling agent). Statistical analysis results showed that the obtained models have met standard requirements of response surface models with good predictive capability. One of the important finding of this study was the formulation for optimum coupling agent proportion which gives the best flexural properties of composite. The effect of straw fiber size on composite properties was investigated by using fiber length and aspect ratio as parameters to describe fiber size, instead of the size of sieves used in fiber preparation. Two-stage separation method was applied in the straw fiber preparation process. In this method, width-based separation was followed by length-based separation to obtain fiber fractions with distinct fiber length and aspect ratio. Samples of thermoplastic composites for measurement of physical properties were produced from each fiber factions at two different levels of fiber loading. The samples were compounded by twin-screw extrusion and specimens were prepared by injection molding. The fibers were then extracted from the samples after injection molding (using solvent) and their sizes were measured to investigate the fiber size reduction during the compounding and molding process. A comprehensive analysis was then performed to study the responses of stiffness, impact resistance and specific properties of these composites by including initial fiber sizes, fiber chemical compositions (measured as cellulose, hemi-cellulose and lignin), fiber size reduction during compounding/molding process, and fiber loading as factors. One of the important contributions of this study is fiber grading in terms of their sizes and their respective contributions to the final composite product properties. Based on the previous results, a mixture design of experiment was performed on wheat straw – polypropylene / impact copolymer polypropylene (WS-PP/ICP) composite system. The objective of the experiment was to obtain response surface models that can be used to estimate some important properties required by a set of automotive product specifications. The optimum formulation of coupling agent obtained in the previous study was used to determine the fixed recipe of coupling agent; simplifying the composite system into a three-component mixture, i.e. straw (as fiber) and polypropylene (homopolymer and impact copolymer (polypropylene blend as matrix). Simulation of the models shows the superiority of using a blend of polypropylenes to balance the stiffness and impact strength of the composites and being able to reach three targeted product specifications. A case study was also performed to demonstrate that the models can be used to find optimum formulations to minimize material cost while meeting specifications of all targeted products. Finally, a framework for wheat straw polypropylene product design and development is presented in this thesis. The framework can be used for designing polypropylene-straw thermoplastic composites with various combinations of fiber - polymer matrix - additive systems with different product attributes and specifications suitable for several applications in the automotive industry.

Minimising variability in carcass quality to better meet market specifications is a priority for Australian pig producers, however issues with variability in carcass fat distribution have recently been raised, particularly in the belly primal. There has been a rapid increase in the use of low-cost, deep-litter (DL) housing systems in Australia over the past 15 years for rearing pigs. The inherent differences between the physical, thermal, and social environments of conventional (C) and DL production systems may well alter the growth path of the pig and subsequently alter fat metabolism and hence fat deposition and distribution. The general industry view is that pigs finished in DL housing are fatter and grow less efficiently than pigs finished in C housing, however contrasting carcass and growth performance results have been reported between housing systems. It is likely that the different housing environments affect the maintenance energy requirements of the growing pig, thereby affecting the availability of substrates for fat deposition and/or the requirements for fat mobilisation. Hence, raising pigs in C and/or DL production systems was identified as a likely contributor to variability in carcass fat distribution via the effects of the disparate environments on fat metabolism. The overall purpose of this thesis was to establish the effect of keeping pigs in C and/or DL housing systems on fat metabolism, and therefore fat deposition in the growing pig and fat distribution in the finished carcass. Industry considers that finishing pigs in C facilities allows greater flexibility in feeding and marketing decisions, allowing growth efficiency and backfat to be managed more effectively than in a DL system. Therefore an aspect of this thesis was to also examine the effects of an alternative management strategy, raising pigs in a combination of DL and C housing, on growth performance and fat deposition and distribution in the carcass. The presence of straw bedding is a major difference between C and DL housing systems. This was identified as a probable contributor to the differences in growth performance and carcass fat distribution found between pigs raised in the different housing systems, via its thermal properties and/or the ingestion of the straw on pig growth. Experiment 1a and 1b were designed to test the hypothesis that the growth path differs for pigs raised in C and DL housing systems, affecting biochemical indicators of fat metabolism and therefore fat accretion and distribution in the carcass. The study was conducted as a serial slaughter of pigs housed in C and DL systems allowing the pattern of fat accretion, and therefore the distribution of fat in the carcass, to be determined from 15¨C185 kg live weight (LW). The results confirmed the hypothesis that the growth path, fat accretion and fat distribution in the carcass differed for pigs raised in C and DL housing systems. In Experiment 1a, elevated lipogenic enzyme activities, higher percentages of saturated fatty acids (SFA) and higher concentrations of plasma glucose and lactate indicated lipogenesis was elevated in C pigs to 13 weeks of age, compared to young DL pigs, suggesting that fat accretion was higher in young C pigs. At 24 weeks of age however there was a shift in lipogenic enzyme activities, the percentage of SFA in backfat and the concentration of plasma glucose were higher in DL-housed pigs than C-housed pigs, indicating higher rates of lipogenesis. Elevated concentrations of plasma non-esterified fatty acids (NEFA) and glycerol in DL pigs indicated that lipolysis, or fat mobilisation, was higher in DL-housed pigs for the entire growth period. The results from Experiment 1b clearly indicated that during early growth, C pigs grew faster than DL pigs (0.71 vs 0.66 kg/day, P¡Ü0.05) and were heavier between 8-23 weeks of age (P¡Ü0.05). Therefore in conjunction with the results of Experiment 1a, it was expected that young C pigs would be fatter than DL pigs of the same age. However, dissection indicated no treatment differences in total carcass composition, although there was an effect of housing on carcass fat distribution with a trend (P=0.087) for a lower ratio of fat:lean in the belly primal of DL pigs compared to C pigs at 13 weeks of age. After 20 weeks of age however, growth rates were similar for pigs in both housing treatments and by 26 weeks of age there were no treatment differences in live weight (LW) but the rate of fat accretion in DL pigs, particularly in the loin and belly primals, increased rapidly. Differences in the thermal environments of C and DL housing, and therefore differences in the energy demand for thermoregulation, were likely to have contributed to the differences measured in lipogenesis, growth performance and carcass fat distribution. Experiment 2a and 2b tested the hypothesis that moving pigs from DL to C housing for finishing would improve overall growth performance and reduce carcass fatness compared to pigs raised in wean-to-finish DL housing. The biochemical measurements indicated few differences in the rate of lipogenesis between 13-week-old C and DL pigs. However, and in agreement with the findings from Experiment 1a, elevated plasma NEFA concentrations in DL pigs suggested higher rates of lipolysis. Up to 13 weeks of age, pigs in the DL housing system grew faster than C pigs, however similar to the findings of Experiment 1b, DL pigs were less efficient. In addition, P2 backfat depth was less in DL pigs, indicating they were leaner than C pigs, and though not reflected in total carcass composition, again there was an effect of housing on fat distribution. The move to an unfamiliar housing environment affected growth performance, reduced enzyme activity in backfat and the ratio of SFA in belly fat, suggesting these pigs had lower rates of lipogenesis. However in contrast to Experiment 1a, where lipogenesis was higher in older DL pigs compared to older C pigs, pigs finished in the DL housing had a trend for lower enzyme activity in belly fat (P=0.063), suggesting lower rates of lipogenesis, and higher plasma glycerol concentrations, suggesting a higher level of lipolysis compared to C-finished pigs. The carcass composition data (Experiment 2b) found that though there were no differences indicated by differences in P2 depth, there was a strong trend (P=0.057) for DL-finished pigs to have 2-6% less fat in the carcass as a result of significantly less fat in the shoulder (15% vs 17%) and belly (29% vs 33%) primals compared to C-finished pigs. The difference in belly primal composition was a reflection of the lower enzyme activities in belly fat and higher plasma glycerol concentrations in DL finished pigs. The results suggest that the type of housing during the finishing growth period has a greater impact on fat accretion and carcass composition than the type of housing during the grower period, or changing housing environment during growth. However, changing housing environment at 13 weeks of age affected growth, where there was a temporary reduction in daily LW gain, and therefore significantly lower (P¡Ü0.001) LW at slaughter (117 kg LW), compared to pigs that had remained in C or DL housing from wean-to-finish (123 kg LW). Moving pigs from DL to C housing to control carcass fat and improve growth performance compared to pigs grown wean-to-finish in DL housing, was not successful, and had a negative impact on performance and carcass quality by reducing growth efficiency and LW and increasing carcass fatness. The results also showed that contrary to the industry view that DL raised pigs are fatter, pigs in this experiment finished in DL housing had a lower fat:lean ratio in the carcass than pigs finished in the C system (P¡Ü0.05). The effects of straw on growth performance and carcass composition were evaluated in Experiment 3a and 3b by including straw in the grower and finisher diets (St+) and/or providing straw bedding (Bed+) to C-housed pigs. The experiment tested the hypothesis that the presence of straw alters the growth paths of pigs, affecting fat distribution in the carcass. Straw, as bedding and in the diet, affected pig growth paths and altered carcass fat distribution and, consistent with the findings for DL pigs in Experiments 1b and 2b, there was a trend for pigs with access to straw to have less fat in the belly (P=0.072). Elevated activity of key enzymes involved in lipogenesis, measured in Experiment 3a in belly fat and backfat from pigs fed the St+ diet, and a higher ratio of SFA in belly fat of pigs housed on concrete without straw bedding, suggested that in this experiment straw ingestion increased lipogenesis in belly fat and backfat of the growing pig, whilst straw bedding reduced lipogenesis in belly fat. Experiment 3b demonstrated an additive effect of straw on growth where average LW at slaughter for pigs without access to straw was significantly lower (110 kg), compared to pigs with access to one source of straw either via the diet or bedding (115 and 114 kg LW respectively), and pigs that had two sources of straw available (119 kg LW) (P¡Ü0.05). Although LW differed between treatments there were no differences in total carcass fat (P>0.10), yet there was an effect of straw on fat distribution. Pigs with access to straw had a lower ratio of fat and a higher ratio of lean tissue in the belly primal (P=0.072) compared to pigs that did not have straw. The effect of straw ingestion on lipogenesis and fat deposition may have occurred via the effects of dietary fibre (DF) on the dilution of dietary energy density. Pigs were able to compensate for the energy/nutrient dilution by increasing VFI and therefore growth was not affected, however fat acts as an insulator, and localised differences in fat distribution may have been related to increased heat production (HP) from the digestion of greater volumes of feed. In response, fat deposition may have been directed away from the belly location in order to facilitate heat loss. Floor type may have also affected fat distribution via differences in thermal conductivity. Straw has a lower thermal conductivity than concrete, hence pigs housed on concrete flooring may have a greater requirement for fat in the belly to reduce conductive heat loss. Results from Experiment 3a and 3b provided evidence that pigs housed on bedding consume straw in sufficient quantities. Pigs fed the straw diet had significantly higher concentrations of plasma acetate than pigs fed the control diet (P¡Ü0.001), and there was a trend for pigs housed on straw bedding to have higher levels than pigs without access to straw. An increase in plasma acetate can indicate increased microbial activity in gut, which occurs in response to higher levels of DF. In addition, pigs bedded on straw had higher gastrointestinal tract weights, which can also indicate higher levels of DF intake. Regression analyses of data across experiments showed that P2 backfat depth, the primary carcass composition prediction tool, accounted for less than 50% of the variation in percent carcass fat (R2=0.41). Furthermore, across experiments, P2 accounted for very little of the variability in percent belly fat (R2=0.01). These results highlight the inconsistency of P2 depth as a reliable indicator of carcass composition and the need for the development of additional criteria to be used in the selection of carcasses for specific markets as the composition of the belly primal was not indicated by the current carcass measurement system. From the results obtained in this thesis, it was proposed that: 1) The growth path of pigs is altered by the housing system in which they are reared and the more variable ambient temperature of the DL housing system would increase the energy requirement of young pigs for thermoregulation. As a consequence of the altered growth paths, fat metabolism differs for pigs raised in DL and C production systems. Lower rates of lipogenesis may occur in young DL pigs compared to C pigs and this can change as pigs grow, however fat mobilisation remains higher in DL pigs during growth. 2) Differences in the rate of lipogenesis, indicated by the biochemical measures, were generally not reflected in total carcass composition, however there were differences in carcass fat distribution where pigs raised in DL systems consistently had less fat in the belly primal. Rearing environment may provide an additional criterion when selecting carcasses for specific markets where variability in belly composition is an issue. 3) Pig raised in the DL environment are not always fatter than pigs housed in C facilities, and moving pigs from one housing environment to another during the growing-finishing period disrupts the growth path reducing growth performance and can increase carcass fatness. 4) Straw bedding, via ingestion and via its physical thermal properties, affects pig growth and fat distribution and may explain in-part the differences in pig growth performance and carcass quality found between C and DL housing systems.