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This thesis investigates the performance of diamond-shaped dowel joints in concrete slabs on ground under static loads. Diamond-shaped dowels have been in common use in concrete slab construction since 1996. A comprehensive literature review revealed that published studies regarding laboratory tests and finite element modelling of diamond-shaped dowel performance were limited to primary experiments and simple numerical analysis. Importantly, the limited finite element modelling has not been verified against test data, and the scant published test data lacks clarity. The results were inconclusive, unclear and there exists different recommendations for joint stability. Some recommended design data are not based on any testing, but on inferred or extrapolated data from smaller slabs with smaller dowel thicknesses. Hence, this research provides the opportunity to enlighten the design community with real data on the performance of diamond-shaped dowel joint behaviour. The research program includes experimental, numerical modelling and parametric evaluations. In the experimental investigation, testing facilities were designed and developed in the course of this research. A total of one trial and six cast-in-place slabs encompassing two slab thicknesses, two diamond-shaped dowel thicknesses, and two dowel spacing, were tested in the structures laboratory of the Division of Civil Engineering at the University of Queensland. Joint gaps of 10 or 15 mm were used to simulate typical slab contraction causing by the shrinkage of concrete slabs. All tests were subjected to static loading to failure. This enabled slab joint response to be evaluated in terms of relative deflection, load transfer efficiency, load transfer, ultimate load and crack geometry. In addition to the experiments, numerical models were developed using the LUSAS finite element program. The model dimensions corresponded to those of the laboratory test specimens. The concrete slabs were modelled using a “multi-crack concrete model 94”. The test rig, diamond-shaped dowels and other materials were modelled as elastic materials. Results from the laboratory experiments were compared to the finite element results in order to validate the model. These models were then used to undertake a preliminary parametric study of diamond-shaped dowel performance. Criteria such as joint gap widths, dowel spacing, concrete property reduction, and dowel and slab thickness were investigated. The three main sections of this work - comprising laboratory testing, finite element modelling and parametric study evaluating have been combined to provide a betterinformed understanding of the performance of concrete slabs using diamond-shaped dowels.

To investigate the fundamental mechanism of friction stir welding to form a butt joint, two additional tests are performed, one using the rotating probe pin only, the other using the rotating shoulder only. In the first case, the pin tool is plunged into the joint interface, but the shoulder is not in contact with the workpiece. When the pin tool is feeding, the material in the vicinity of the pin tool is scratched and piled on the retreating side, but a butt joint is not formed by this test on two thin plates of aluminum alloy 6061-T6. In the second case, when the shoulder is feeding, the plastic shear deformation of the material in the vicinity of the shoulder can be observed and then it is joined together due to the heat generated from the shoulder to cause the material diffusion. According to these additional experiments and the friction stir welding process, the mechanism to form a butt joint is as following. When the probe plunge into the material and the shoulder is in contact with the workpiece, a large amount of frictional heat is generated from the shoulder and the pin. When the tool moves forward, the soft material in front of the pin is squeezed, so that the material is refilled into the space behind the pin by the rotating pin and shoulder. According to the observation of cross-section of butt joint, an interface curve can be found. This curve is formed by the plastic shear deformation of the material in the vicinity of the shoulder and the pin at high frictional temperature. It can be explained by the boundary layer theory.

<p> There is mounting pressure to find suitable disposal sites for both household and industrial waste in south-central Ontario as a solution to Metropolitan Toronto's growing 'garbage crisis'. New data indicate that the fine-grained glacial sediments of south-central Ontario, previously considered to be 'tight' and impermeable, are in fact penetrated by an extensive joint system. This thesis provides basic information regarding the regional character, orientation and origin of joints within the surficial glacial sediments and bedrock of south-central Ontario. Three regional joint sets can be identified. Within the bedrock, the joint sets are oriented northeast/southwest, northwest/southeast and north/south. This trend is consistent with the regional jointing pattern within the overlying glacial sediments and suggests that the joints may have propagated from the bedrock into the glacial sediments. A comparison between the regional jointing pattern identified in bedrock and glacial materials and the orientation of stress release structures suggests that the regional pattern of jointing is controlled by the regional stress field which results from intraplate tectonic stresses. However, the orientation of joints at any individual site may also be controlled by 'local' factors such as face orientation, direction of glacial ice movement and lithology and by randomly oriented joints formed as the result of physical and chemical weathering, synaeresis, subglacial deformation and stress relief. The identification of regional jointing pattern within south-central Ontario allows the prediction of joint characteristics and orientations at potential landfill sites in the region, critical to the accurate evaluation of the permeability of the substrate materials.</p> / Thesis / Master of Science (MSc)

The problem was to design and construct the necessary equipment to cut and fasten short stock end to end using finger-joints. The study was divided into five chapters: I contained the introduction to the problem; II was concerned with the design and construction of the equipment; III detailed the operation of the equipment; IV contained the presentation of the data; and V covered the summary and findings. The study concluded that the equipment could be constructed inexpensively, and would perform a useful service. Also, a student using waste wood salvaged through use of this equipment could expect a smaller bill for materials than if he purchased new wood.

The gluing of unseasoned wood, called green gluing, is a relatively new sawmill process, implying a radically changed order of material flow in the production of value-added wood-based products. It facilitates the enhancement of raw material recovery and value yield by integrating defect elimination and gluing already before kiln drying. The present study evaluates green glued adhesive bonds in flatwise glued beams and finger joints. The main part of this work deals with green gluing using a moisture curing polyurethane adhesive (PUR). Standardised test methods and specially designed, small scale, specimens were used for the determination of the strength, fracture energy and the ductility of both dry- and green glued bonds in tension and in shear. Using the small scale specimens it was possible to capture the complete stress versus deformation curves, including also their unloading part. An optical system for deformation measurement was used for the analysis of bond behaviour. The influence of moisture content during curing and temperature after curing on the adhesive chemical composition and on the mechanical properties was investigated. Furthermore, the moisture transport through the adhesive bond during curing was tested. Finally, microscopy studies were performed for analysis of bond morphology and fracture. The results show that two significant factors influence the shear strength of green glued bonds: wood density and adhesive spread rate. Bonds which fulfil the requirements according to EN 386 could be obtained within a wide range of process parameters. The small specimen tests showed that green glued PUR bonds can reach the same strength and fracture energy, both in shear and in tension, as dry glued bonds with the same adhesive amount. The local material properties of the bonds could be determined, thanks to the failure in the tests taking place within the adhesive bond itself and not in the wood. Following process factors were shown to cause lower bond strength: a) a low adhesive spread rate, b) high pressure and c) short pressing time in combination with low wood density and high moisture content. Moreover, the heat treatment of the cured PUR adhesive during drying influenced the chemical composition of the adhesive, providing for higher strength, stiffness and Tg of the adhesive, caused by an increased amount of highly ordered bidentate urea.

This thesis has been conducted for the Luleå University of Technology (LTU), Sweden as part of an inter-university collaboration between LTU and the Montanuniversität Leoben (MUL), Austria.   The project has included three master thesis works, all investigating some aspects of the effects of jointing on fragmentation through small scale tests.   The topic of this thesis has been to develop a method for representing/introducing artificial joint planes into concrete blocks and subsequently manufacture a number of specimens with different joint sets for testing, using block dimensions previously used at MUL. The method for manufacturing the jointed test specimens, developed by the author at LTU, has been evaluated through blasting and fragmentation analysis. Comparison of the different produced joint sets has been done to assess the influence of jointing on fragmentation.   A total of 10 magnetic concrete blocks were produced and evaluated. The 10 blocks had an average density of 2485 ± 41 kg/m3 (mean ± standard deviation). Eight of the 10 blocks contained joint sets (JS) with different characteristics, while two blocks were un-jointed reference blocks. A total of four different joint sets were developed.   The four joint sets had the following properties; JS1: joint spacing 95 mm, strike/dip equal to 0/90°, JS2: joint spacing 47.5 mm, strike/dip equal to 0/90°, JS3: joint spacing 47.5 mm, strike/dip equal to 60°/90° and JS4: joint spacing 89 mm, strike/dip equal to 0/70°.   The produced joints have proven to behave as desired, i.e. being able to reflect incident waves and to stop some incident cracks.   It has been found that there is a strong indication of jointed blocks producing a finer median fragmentation size (x50) than that of the reference blocks. This means that by introducing joint sets into the test specimens the degree of fragmentation by blasting has been increased. This was predicted by the Kuz-Ram model.   Each of the 28 blasted rows has been sieved and analysed. All the data has been fitted to the three parameter Swebrec function, producing an average coefficient of determination (an R-square value) of 0.9946 ± 0.0064.

Acetylation of wood is a modification technique that chemically alters the wood substance and enhances several properties of wood. The basic principle is to impregnate wood with acetic anhydride to react and replace OH-groups with acetyl groups in the wood cell wall. In this way, the hygroscopicity of the modified wood is significantly reduced resulting in increased dimensional stability and durability compared with unmodified wood.The objective of this work was to study finger-jointing of acetylated Scots pine (Pinus sylvestris L.) using a conventional melamine urea formaldehyde (MUF) adhesive. Two different types of acetylated pine specimens were investigated, acetylated pine sapwood (APS) and acetylated juvenile pine (AJP), the latter originating from young forest thinning trees (ca 20-30 years). The goal was to evaluate the bending strength, i.e. modulus of rupture (MOR), of such finger-jointed samples, in particular when the acetylated wood was combined with unmodified wood, in this case, Norway spruce (Picea Abies L. Karst) (US). The finger-jointing were performed at Moelven Töreboda by applying their existing industrial procedures. In total, five different of finger jointed sample groups were prepared combining the different specimens: APS-APS, AJP-AJP, US-US, APS-US, and AJP-US. Standardized procedures were used to determine the MOR of the finger-jointed samples, both unexposed at the factory condition state and after a water-soaking-drying cycle. In addition, the experiments also included determination of the moisture content (MC), density, and modulus of elasticity (MOE) (in bending along the grain) of the individual specimens.At the unexposed state, the APS-APS samples showed the highest MOR of 63,1 MPa, while those of the AJP-AJP showed the lowest value of 42,4 MPa. The corresponding values for the US-US, AJP-US and APS-US samples was 56,7, 47,5 and 46,9 MPa, respectively. In contrast to a typical wood failure for the US-US samples, a low amount of wood failure was observed in all cases involving the acetylated wood, indicating a low adhesive anchoring in the wood substrate at the finger-joint, although a surprisingly high strength was obtained for the APS-APS samples. A significantly lower MC content of 4,9 % and a remarkably low value of 1,7 %, was found for the APS and AJP, respectively, compared with 9,2% for the US. The significantly lower MC combined with an assumed increased hydrophobicity of the acetylated wood possible causes a less effective MUF-wood bonding, or adhesion, compared with that of the unmodified wood. Possible, so-called over penetration of the MUF resin in the acetylated wood could also be an explanation for the poor wood-adhesive anchoring. The MOE of the individual APS, AJP and US specimens was 12,6, 8,3 and 11,4 GPa, respectively, indicating a significantly lower mechanical performance of AJP, and hence also of finger-joints of AJP, despite its very low MC, possible due to a higher microfibril angle in the cell walls in juvenile wood compared with mature wood. No clear correlation was found between the MOR and density of the acetylated samples.For the samples exposed to a water-soak-drying cycle, the highest MOR, and lowest reduction of 14 % compared with the unexposed state, was obtained for the US-US samples, whereas all samples involving the acetylated wood showed a distinctly higher reduction. The MOR of the AJP-AJP and AJP-US samples were reduced with 47 % and 50 %, respectively, while the MOR of the APS-APS and APS-US samples were reduced with 43 % and 23 %, respectively. It should be emphasized, however, that after the standard drying-time, which was the same for all samples, the acetylated samples, compared with the untreated ones, did not dry out to the same level as for the dry unexposed state, i.e. the acetylated samples had a high MC of ca 30-40% in these MOR tests. This high MC level could be the main reason for the dramatic strength losses. Furthermore, a less efficient wood-MUF adhesion as well as the drying under acidic conditions may also be possible causes for the reduced bending strength of the finger-jointed samples with acetylated wood.

Des structures prismées sont fréquemment observées dans les coulées de lave comme la Chaussée des Géants (Irlande). Plusieurs théories existent pour expliquer ces formations, dont la plus répandue est celle de la contraction thermique. Or cette théorie permet difficilement de comprendre certaines observations de terrain comme la séparation fréquente des coulées en plusieurs niveaux. Afin de mieux comprendre la structuration au sein des coulées basaltiques, nous avons procédé à une étude pluridisciplinaire basée sur les propriétés magnétiques, les variations structurales et géochimiques de deux coulées prismées du Massif Central (La Palisse, Ardèche et Saint-Arcons-d’Allier, Haute-Loire). Notre approche permet de montrer que les fabriques cristallographiques et magnétiques sont gouvernées par l’écoulement de la lave. L’orientation du plagioclase contrôle la distribution des titanomagnétites à l’origine des fabriques magnétiques. Notre étude montre également que l’utilisation de l’ASM est un outil fiable pour déterminer l’orientation de l’écoulement à condition d’être contrôlée par des mesures de fabriques cristallographiques. Les mesures de la quantité d’eau et les analyses isotopiques (H et O) montrent que l’effet de l’altération météorique est faible et que l’eau contenue dans la roche est essentiellement de l'eau de constitution. De plus, à l’échelle du prisme, des variations de deuxième ordre sont observées comme celle des paramètres d’hystérésis qui indique des tailles de grains de titanomagnétites plus importantes vers le centre. Ces variations au sein du prisme semblent difficilement compatibles avec une structuration des coulées par la simple contraction thermique. / Columnar jointing is frequently observed in lava flows, as in the Giant Causeway (Ireland). The most common theory explaining the formation of prisms is by the thermal contraction. However, this theory hardly explains some field observations such as the frequent existence of three parts within the lavas flows, from the base to the top. To complete our understanding of the structuring lava flows, we carried out a multidisciplinary study based on the magnetic properties, structural and geochemical characterization of two basaltic flows from the French Massif Central (La Palisse, Ardèche and Saint-Arcons-d'Allier, Haute-Loire). Our approach shows that crystallographic and magnetic fabrics are governed by the flow. The distribution of titanomagnetite grains carrying the magnetic fabrics is mainly controlled by the plagioclase orientation. Our study also shows that the use of the AMS to determine the flow direction is a reliable tool, provided punctual control by measurements of crystallographic fabrics are performed. Measurements of the water content and isotopic analyses (H and O) show a limited weathering effect in the studied areas: rock water is mostly primary water in equilibrium with the magma. Moreover, second order changes are noted across the prism section such as hysteresis parameters associated to grain size variation of titanomagnetite (larger grains in the center). The variations of magnetic properties across the prism section suggest a gradient of the crystallization rate from the center to the edge of the prism, which seems difficult to reconcile with the structuring of the flow by thermal contraction only.

A radiometric survey of the zoned 21 Ma, A-type Sheeprock granite, western Utah, combined with measurements of magnetic susceptibility and field observations were analyzed using a geographic information system. The intrusion spans 25 square km and is roughly eliptical in shape with its long axis trending northwest. Concentration maps (composed of more than 500 survey stations) of eU, eTh, texture, magnetic susceptibility, color, and joint density help to constrain magmatic and post-magmatic processes related to its chemical and physical zonation. Uranium ranges from 3.9 to 26.9 ppm (mean 12.7) and thorium from 1.7 to 125.7 ppm (mean 45.5). Similarities in spatial patterns and near normal distributions of U and Th imply minimal remobilization and secondary equilibrium of U. Relatively high magnetic susceptibility (6 to 12*10^-3 SI units), low eU and eTh, and limited whole rock chemical anayses show the southeastern part of the pluton is more mafic and most likely formed as an early cumulate. Dominant textures are porphyritic with a fine-grained matrix along the northeastern margin, coarsening to a medium-grained matrix along the southwestern margin. This transition from fine to medium-grained matrix textures is believed to be a preserved solidification front that had migrated from the roof and walls inward during cooling. Late stage magma mixing is evidenced by a string of mafic enclaves along the axis of the pluton near this solidification front. eU and eTh generally increase toward the finer-grained northeastern margin of the pluton. This has been interpreted to be the primary result of fractionation of U and Th into monazite and thorite. As mafic cumulates formed along the northeastern margin residual liquids were displaced inward. This depleted the more evolved parts of the pluton in U and Th. Beryl, a distinquishing characteristic of the most evolved portions of the pluton, is concentrated in two areas along the central axis of the intrusion. The intrusion is a cumulative of three magmatic phases, the second of which crystallized from the margins inward. Joint spacing is a major factor in controlling post-magmatic processes. The pluton has a higher density of joints (10 cm apart) near the upper margins, and fewer joints (> 1 meter apart) at lower elevations. Differential cooling and magma pressures are believed to have controlled the varying joint densities. Increased alteration, oxidation, and red-staining are more prevalent in areas of higher joint density. Magnetic susceptibility is bimodal. The high mode (5.4*10^-3 SI) is on the low end of magnetite-series granites and occurs most often in the white granite. The low mode (0.07*10^-3 SI) implies significant post-magmatic oxidation and the destruction of magnetite and correlates to the red granite. Truncated chemical and textural patterns along the pluton's northwestern margin support evidence for range front normal faulting.