Spider aggregate glue is secreted on to the webs of many spiders in the superfamily Araneoidea. Aggregate glue is sticky when wet and has a unique stress strain curve that varies depending on the relative humidity and speed of probe retraction. These features make it an attractive target for applications such as underwater adhesives or surgical glues. However, little is known about the genetic sequence of the glue protein itself. In this work, a method is identified to isolate the remainder of the aggregate gene sequence, and genetic constructs glue are created using known aggregate gene sequence. One construct is expressed in E. coli BL21 cells and the protein is tested for its adhesive properties.

The growing demand of construction aggregates has raised concern about the availability of natural aggregates. Over two billion tons of natural aggregate are produced each year in the United States and that number is expected to increase to 2.5 billion tons by 2020. This has raised concern about the availability of natural aggregate. Discarding demolished concrete into landfills is a costly solution from an economical and environmental point of view. Many U.S. highway agencies are re-using Recycled Concrete Aggregates (RCA) as construction material. The use of fiber reinforcement in Portland Cement Concrete (PCC) has recently become a popular option in concrete construction because of its influence on preventing segregation, reducing early shrinkage cracks and increasing residual load capacity. Alkali-Silica Reaction (ASR) is a major problem in concrete, especially when using RCA, causing concrete expansion and cracks. Recently lithium has been found to reduce expansion due to ASR. This thesis will investigate the effect, of fibers soaked in lithium nitrate on the mechanical properties of RCA.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24236号 / 工博第5064号 / 新制||工||1790(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 関 修平, 教授 今堀 博, 教授 杉安 和憲 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

This dissertation is dedicated to develop models and methods to bridge atomistic and continuum scales of deformation processes in asphalt-aggregate interfacial composite materials systems. The deformation and failure behaviors, e.g. nanoscale strength, deformation, stiffness, and adhesion/cohesion at asphalt-aggregate interfaces are all evaluated by means of atomistic simulations. The atomistic modeling approach is employed to simulate mechanical properties, which is connected by their common dependence on the nanoscale bonding and their sensitive dependences on mechanics and moisture sensitivity. Specifically, CVFF-aug forcefield is employed in the atomistic calculations to study the fundamental failure processes that appear at the interface as a result of a mechanical deformation. There are five primary aspects to this dissertation. First, the multiscale features of asphalt concrete materials are characterized by using nanoscale characterization & fabrication devices, e.g. High Resolution Optical Microscope (HROM), Environmental Scanning Electron Microscope (ESEM), Transmission Electron Microscope (TEM), Focused Ion Beam (FIB), and Atomistic Force Microscope (AFM). Second, based on the multiscale devices characterization of the interfaces, a 2-layer atomistic bitumen-rock interface structure is constructed. Interface structure evolution under uniaxial tension is performed with various deformation rates. Comparison is made between both theoretical and experimental characterizations of interface configuration. Molecular dynamics (MD) simulations are used to investigate potential relationships between interface structure and morphology. Influences of deformation rate and temperature factors are discussed in terms of interface region stress-strain relation and loading time duration. Third, molecular dynamics simulations are also performed to provide a characterization of atomic scale mechanical behaviors for a 3-layer confined shear structure which leads to interfacial shear failure. In addition, atomistic static simulation approach is employed to calculate a couple of mineral crystals' elastic constants. Furthermore, molecular dynamics simulations are also used to predict the static, thermodynamic, and mechanical properties of three asphalt molecular models. Fourth, the high performance parallel computing technology is extensively employed throughout this dissertation. In addition to use the large-scale MD program, LAMMPS, the author developed a high performance parallel distributive computing program, MPI_multistress, to implement the multiscale understanding/predicting of materials mechanical behaviors. Finally, this research also focuses on the evaluation of the susceptibility of aggregates and asphalts to moisture damage through understanding the nano-mechanisms that influence adhesive bond between aggregates and asphalt, as well as the cohesive strength and moisture susceptibility of the specific asphalt-aggregate interfaces. Surface energy theory and pull-out simulation are used to compute the adhesive bond strength between the aggregates and asphalt, as well as the cohesive bond strength within the binder. In general, this dissertation has focused on the development of nanoscale modeling methods to assess asphalt-aggregate interfacial atomistic deformation and failure behaviors, as well as moisture effects on asphalt mixture strength. Simulation results provide valuable insights into mechanistic details of nanoscale interactions, particularly under conditions of various deformation rates and different temperatures. The results obtained show that a reasonable agreement between the theoretical and pavement industry observations is satisfactory. We conclude that the theoretical calculations presented here are useful in asphalt concrete industry for predicting the mechanical properties of asphalt-aggregate interfaces, which are difficult to obtain experimentally because of their small size. / Ph. D.

Concrete undergoes volumetric changes throughout its service life. These changes are a result of applied loads and shrinkage. Applied loads result in an instantaneous recoverable elastic deformation and a slow, time dependent, inelastic deformation called creep. Creep without moisture loss is referred to as basic creep and with moisture loss is referred to as drying creep. Shrinkage is the combination of autogeneous, drying, and carbonation shrinkage. The combination of creep, shrinkage, and elastic deformation is referred to as total strain. The prestressed concrete beams in the Chickahominy River Bridge have been fabricated with a lightweight, high strength concrete mixture (LTHSC). Laboratory test specimens have been cast using the concrete materials and mixture proportions used in the fabrication of the bridge beams. Two standard cure and two match cure batches have been loaded for 329 and 251 days, respectively. Prestress losses are generally calculated with the total strain predicted by the American Concrete Institute Committee 209 recommendations, ACI 209, or the European design code, CEB Model Code 90. Two additional models that have been proposed are the B3 model by Bazant and Baweja, and the GL2000 model proposed by Gardner and Lockman. The four models are analyzed to determine the most precise model for the LTHSC mixture. Only ACI 209 considered lightweight aggregates during model development. GL2000 considers aggregate stiffness in the model. ACI 209 was the best predictor of total strain and individual time dependent deformations for the accelerated cure specimens. CEB Mode Code 90 was the best predictor of total strain for the standard cure specimens. The best overall predictor of time dependent deformations was the GL2000 model for the standard cure specimens. / Master of Science

Yes / Test results of nine recycled aggregate concretes and a control concrete using only natural aggregates are reported. The recycled aggregates used were classified into three different types according to their measured specific gravity and water absorption, namely, RG I for recycled coarse aggregate having a specific gravity of 2.53 and water absorption of 1.9%; RG III for recycled coarse aggregate having a specific gravity of 2.4 and water absorption of 6.2%; and RS II for recycled fine aggregate having a specific gravity of 2.36 and water absorption of 5.4%. The replacement levels of both recycled coarse and fine aggregates were 30, 50, and 100% in separate mixtures. Slump loss and the amount of bleeding with time were recorded for fresh concrete. Compressive and tensile strengths, moduli of rupture and elasticity, and unrestrained shrinkage strain were also measured for hardened concrete. The properties of fresh and hardened concrete tested, together with a comprehensive database reported in the literature, were evaluated with respect to the relative water absorption of aggregates combining the quality and volume of recycled aggregates used. In addition, the properties of hardened concrete with different replacement levels and quality of recycled aggregates were compared with the design equations of ACI 318-05 and empirical equations proposed by Oluokun for natural aggregate concrete, whenever possible. Test results clearly showed that the properties of fresh and hardened concrete containing recycled aggregates were dependent on the relative water absorption of aggregates. In addition, the moduli of rupture and elasticity of recycled aggregate concrete were lower than the design equations specified in ACI 318-05, when the relative water absorption of aggregates is above 2.5% and 3.0%, respectively.

Researchers investigated how the contingent delivery of a cultural consequence on target culturants in an asymmetric iterated prisoner's dilemma game (IPDG) affected players' choices. The asymmetric IPDG creates an analogue to income disparities created by wage gaps and other cultural practices that create wealth inequalities between different members of the population and allows researchers to explore how these inequalities affect cooperation between players. Six undergraduate students divided into three dyads participated in an ABABCDCD reversal design. An asymmetric IPDG was arranged in Condition A and C such that one player received a greater number of points regardless of the second participants' selections - analogue to contingencies that produce income inequalities from wage gaps. In Condition B and D, a metacontingency was arranged such that delivery of a cultural consequence (CC; bonus points equally distributed among the dyad) was contingent on the oscillating production of target aggregate products (AP) across two consecutive cycles. When participants' coordinated responding and contacted the target AP→ CC relation, the wage gap was reduced. However, individual contingencies are in direct competition for the "wealthier" player, reducing the probability of cooperative responding. Results showed the CC selected certain oscillations between target APs resulting in a decrease of a point disparity between the players while also establishing equal points between the players during certain conditions.

Despite applications of foamed bitumen technology in pavement construction in various places around the world, there are still several aspects about this technology that are not clear. In addition, knowledge on foamed bitumen technology is mainly empirical and lacks scientific basis. This study addresses some of the aspects for foamed bitumen technology such as: Investigation of any effects in binder composition during the production process for foamed bitumen; assessment of the effect of bitumen source on foamed bitumen characteristics; development of a rational method to optimise foamed bitumen characteristics and conditions; evaluation of aggregate particle coating within foamed bitumen mixes; further improvements in the mix design procedure specifically the method of compaction and optimum bitumen content determination stages are suggested.  Fourier transform infrared spectroscopy techniques were used to investigate any changes in bitumen composition after the production process of foamed bitumen. Fourier transform infrared tests were done on foamed bitumen and neat bitumen specimens for two bitumens with similar penetration grades. Foamed bitumen characteristics of three bitumens were established by producing foamed bitumen at temperatures of 150ºC up to 180ºC and foamant water contents of 1, 2, 3, 4 and 5%. From the analysis of variation of foamed bitumen characteristics (maximum expansion ratio and half-life) at different temperatures a new method based on the equi-viscous bitumen temperature to optimize foamed bitumen conditions and characteristics was proposed. Rice density and surface energy concepts were used to evaluate aggregate particle coating with foamed bitumen. A granite aggregate divided into three different size fractions and three sets of foamed bitumen produced from three bitumen penetration grades were used. A gyratory laboratory compaction procedure for laterite gravels treated with foamed bitumen was established using the modified locking concept. Three laterite gravels with different chemical composition were mixed with foamed bitumen produced from one penetration bitumen grade. The resulting mixes were compacted up to 200 gyrations and the corresponding compaction curve defined in terms of height versus number of gyrations noted. In addition, the optimum moisture content requirements at the modified locking point were determined. 3D packing theory concepts, primary aggregate structure porosity and an indirect tensile strength criteria were employed to determine optimum bitumen content for foamed bitumen mixes.  Fourier infrared techniques revealed that foaming did not cause any changes in the bitumen chemistry, implying that the foamed bitumen production process may possibly be a physical process. Characterisation of foamed bitumen produced from three bitumen penetration grades showed that foamed bitumen characteristics (maximum expansion ratio and half-life) were mainly influenced by binder viscosity rather than the source. The equi-viscous temperature seemed to provide a suitable criterion at which foamed bitumen with optimum characteristics could be produced. Rice density results showed that aggregate size fraction, binder expansion ratio and viscosity influenced aggregate particle coating. For the coarser aggregate fraction, results revealed that binder coating seemed to be mainly influenced by temperature. Whilst for fine aggregate fraction the coating was mainly influenced by surface area. Surface energy results revealed that foamed bitumen exhibited better coating attributes than neat bitumen. A new laboratory compaction procedure for laterite gravels treated with foamed bitumen based on the modified locking point was developed. The modified locking point represents the state at which maximum aggregate particle interlock occurs when mixes are compacted in the field. It is based on the iii analysis of the rate of change for the gyratory compaction curve. The compaction curve in this case is defined in terms of compaction height versus number of gyrations. Gradation analysis beyond the modified locking point showed that aggregate particle breakdown occurred. Analysis of the optimum moisture at the modified locking point revealed that the moisture conditions were less than the aggregate optimum moisture conditions. It is recommended that this point be used to determine the optimal compaction characteristics of foamed bitumen mixes.  Aggregate structure porosity and an indirect tensile strength criteria can be used to determine the bitumen content that could be used in design of foamed bitumen mixes. This would reduce the amount of resources required since the bitumen content could be estimated prior to carrying out the actual laboratory work given that the aggregate grading is known. The aggregate structure can be divided (based on 3D packing theory) into oversize, primary, and secondary structures. The primary structure is mostly responsible for carrying loads whilst the secondary structure fills the voids within the primary structure and provides support to the primary structure. The aggregate size particles constituting the primary structure are deduced as a function of standard sieve sizes using the packing theory concepts. The minimum sieve size for the primary structure is proposed as 1 mm. The oversize structure consists of aggregate particles whose size is greater than the maximum size for the primary structure. The secondary structure consists of aggregate particles whose size is below the minimum size for the primary structure. The primary aggregate structure porosity can be used to establish the starting bitumen content; the bitumen content at which this porosity is 50% is chosen as the initial bitumen content. Indirect tensile strength values corresponding to 50% primary porosity are determined as well as the bitumen contents and compared against the recommended minimum values. / <p>QC 20161012</p>

Submitted by Erika Demachki (erikademachki@gmail.com) on 2014-09-24T21:42:24Z No. of bitstreams: 2 COUTO, T.A. - RAA Estudo do fenômeno em rochas silicosas 2008.pdf: 9649591 bytes, checksum: 0ecde13fd55a962ac1bc6a8f43f44415 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-09-25T10:37:27Z (GMT) No. of bitstreams: 2 COUTO, T.A. - RAA Estudo do fenômeno em rochas silicosas 2008.pdf: 9649591 bytes, checksum: 0ecde13fd55a962ac1bc6a8f43f44415 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-09-25T10:37:27Z (GMT). No. of bitstreams: 2 COUTO, T.A. - RAA Estudo do fenômeno em rochas silicosas 2008.pdf: 9649591 bytes, checksum: 0ecde13fd55a962ac1bc6a8f43f44415 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2008-08-29 / The symposium on Alkali-Aggregate Reaction (AAR) held in Goiânia in 1997 led to a greater dissemination of this deleterious reaction in Brazil, motivating engineers to find solutions for the problem. Recently, in Brazil, this occurrence has occurred in several building foundations in the Recife metropolitan area besides hydraulic powers plants, as can be seen in some publications from the last AAR Symposium in 2006. This study presents an investigation of several aggregates commercially used in the State of Goiás, Brazil, in order to determine their potential reactivity. In addition, their behavior were compared to the ones from aggregates from several Brazilian classic cases such as Furnas HPP (MG), Moxotó HPP (AL/BA), Pedro Beicht Dam (SP/MG) and Jaguara HPP (SP), beyond aggregates used in civil works of Pernambuco and also a highly reactive basalt from Paraná. The experimental program tested twenty-two rock samples with varied lithology and two local types of cements that had the same clinker (cement A and B). The research uses petrographic analyses, accelerated mortar bar test (NBR 15577), chemical test method (NBR 9774) and accelerated concrete prisms test (based on NBR 15577), to assess the reactivity of the rocks. The results indicate that aggregates show varied expansivity and reactivity among them and sometimes one specific aggregate present different behavior by comparing the results form the test methods performed. This study also discusses the possibility of preventing deleterious expansion from tested aggregates by using the correct type of cement. / Desde 1997, quando as reações expansivas do tipo álcali-agregado ganharam uma maior difusão no âmbito nacional com o primeiro Simpósio sobre Reação Álcali- Agregado (RAA), foi observado um envolvimento mais expressivo de diversos profissionais da área na busca de soluções para este problema. Atualmente, no Brasil, esta manifestação patológica que até então, de uma maneira geral, era exclusiva de obras hidráulicas, já vem sendo observada em estruturas residenciais e comerciais dentro de grandes centros, como os casos relatados da região metropolitana de Recife durante o segundo Simpósio sobre RAA em 2006. No estado de Goiás esta preocupação não foi diferente e, em virtude disto, este trabalho tem por objetivo apresentar a investigação da potencialidade reativa de agregados deste estado comparando com o comportamento de agregados procedentes de algumas obras que representam casos clássicos brasileiros com a UHE Furnas (MG), UHE Moxotó (AL/BA), Barragem de Pedro Beicht (SP) e UHE Jaguara (SP), além de agregados utilizados em obras civis de Pernambuco e um basalto altamente reativo do Paraná. Foram, portanto, selecionados vinte e dois agregados com litologias variadas para este trabalho. A utilização da técnica de petrografia e do método acelerado em barras de argamassa (NBR 15577) foram objeto de estudo da pesquisa, incluindo a análise dos agregados por meio do método químico (NBR 9774) e pelo método dos prismas de concreto (NBR 15577), adaptado na versão acelerada. Foram empregados dois tipos de cimento de mesmo clínquer (cimento A e B) procedentes do estado de Goiás. Os resultados indicaram potencialidades reativas variadas entre os agregados e comportamentos distintos entre alguns métodos de ensaio para o mesmo agregado, bem como a viabilidade do combate da RAA, dependendo do cimento empregado.

<p><a>Voids in the mineral aggregate (VMA), as a main volumetric design parameter in the Superpave mixture design method, is an important factor to ensure asphalt mixture durability and rutting performance. Moreover, an asphalt mixture’s aggregate skeleton, related to VMA, is another important factor that affects critical asphalt mixture properties such as durability, workability, permeability, rutting, and cracking resistance. The objective of this study is to evaluate the effects of aggregate size distribution and shape parameters on aggregate packing characteristics (volumetric and compaction properties) of asphalt mixtures. Three tasks were undertaken to reach this goal. </a></p> <p>The first task was to propose an analytical approach for estimating changes in voids in the mineral aggregate (VMA) due to gradation variation and determining the relevant aggregate skeleton characteristics of asphalt mixtures using the linear-mixture packing model, an analytical packing model that considers the mechanisms of particle packing, filling and occupation. Application of the linear-mixture packing model to estimate the VMA of asphalt mixtures showed there is a high correlation between laboratory measured and model estimated values. Additionally, the model defined a new variable, the central particle size of asphalt mixtures that characterized an asphalt mixture’s aggregate skeleton. Finally, the proposed analytical model showed a significant potential to be used in the early stages of asphalt mixture design to determine the effect of aggregate gradation changes on VMA and to predict mixture rutting performance.</p> <p>As the second task, a framework to define and understand the aggregate structure of asphalt mixtures was proposed. To develop this framework, an analytical model for binary mixtures was proposed. The model considers the effect of size ratio and air volume between the particles on the aggregate structure and packing density of binary mixtures. Based on this model, four aggregate structures, namely coarse pack (CP), coarse-dense pack (CDP), fine-dense pack (FDP) and fine pack (FP), were defined. The model was validated using a series of 3D discrete element simulation. Furthermore, the simulation of multi-sized aggregate blends using two representative sizes for fine and coarse stockpiles was carried out to apply the proposed analytical model to actual aggregate blends. The numerical simulations verified the proposed analytical model could satisfactorily determine the particle structure of binary and multi-sized asphalt mixture gradations and could, therefore, be used to better design asphalt mixtures for improved performance. </p> <p>The third task virtually investigated the effect of shape characteristics of coarse aggregates on the compactability of asphalt mixtures using a discreet element method (DEM). The 3D particles were constructed using a method based on discrete random fields’ theory and spherical harmonic and their size distribution in the container was controlled by applying a constrained Voronoi tessellation (CVT) method. The effect of fine aggregates and asphalt binder was considered by constitutive Burger’s interaction model between coarse particles. Five aggregate shape descriptors including flatness, elongation, roundness, sphericity and regularity and, two Superpave gyratory compactor (SGC) parameters (initial density at N_ini and compaction slope) were selected for investigation and statistical analyses. Results revealed that there is a statistically significant correlation between flatness, elongation, roundness, and sphericity as shape descriptors and initial density as compaction parameter. Also, the results showed that the maximum percentage of change in initial density is 5% and 18% for crushed and natural sands, respectively. The results of analysis discovered that among all particle shape descriptors, only roundness and regularity had a statistically significant relation with compaction slope, and as the amount of roundness and regularity increase (low angularity), the compaction slope decreases. Additionally, the effect of flat and elongated (F&E) particles percentage in a mixture using a set of simulations with five types of F&E particles (dimensional ratios 1:2, 1:3, 1:4 and 1:5) and ten different percentage (0, 5, 10, 15, 20, 30, 40, 50, 80 and 100) with respect to a reference mixture containing particles with flatness and elongation equal to 0.88 was conducted. Results indicated that increase of F&E particles in a mixture (more than 15%) results in a significant reduction in the initial density of the mixture especially for lower dimensional ratio (1:4 and 1:5). <b><i></i></b></p> <br> <p> </p>