Ni-Mn-Ga and In-Tl are two examples of shape memory alloys. Their shape memory effect is controlled by the martensitic transformation from the high temperature cubic phase to the low temperature tetragonal phase. Experimentally, it was found that the martensitic transformation, related to the elastic properties, is highly composition-dependent.In order to better understand the phase transition and facilitate the design of new materials with improved shape memory properties, the atomic scale description of the thermophysical properties of these alloys is needed. Therefore, in the presen tthesis, the elastic properties and phase stability of Ni-Mn-Ga and In-Tl shape memory alloys are investigated by the use of first-principles exact muffin-tin orbitals method in combination with the coherent-potential approximation. We present a theoretical description of the equilibrium properties of pure In and standard stoichiometric Ni2MnGa alloy with both cubic and tetragonal structures. In In-Tl alloys, all the calculated composition-dependent thermophysical properties: lattice parameter c/a, tetragonal shear modulus C" = (C11 - C12)/2, energy difference between the austenitic and martensitic phases, as well as electronic structures are shown to be in line with the experimentally observed lowering of the martensitic transition temperature TM with the addition of Tl. For most of the off-stoichiometric Ni2MnGa, the excess atoms of the rich component prefer to occupy the sublattice of the deficient one, except for the Ga-rich alloys, where the excess Ga atoms have strong tendency to take the Mn sublattice irrespective of the Mn occupation. In Ni-Mn-Ga-X (X=Fe, Co, and Cu) quarternary alloys, Fe atom prefers to occupy the Mn and Ni sublattices even in Ga-deficient alloys; Co has strong tendency to occupy the Ni-sublattice in all types of alloys; Cu atoms always occupy the sublattice of the host elements in deficiency. For most of the studied Ni-Mn-Ga and Ni-Mn-Ga-X alloys with stable site-occupations, the shear modulus C" can be considered as a predictor of the composition dependence of TM of the alloys: the alloy with larger C" than that of the perfect Ni2MnGa generally possesses lower TM except for Ni2Mn1+xGa1-x and Ni2Mn1-xGaFex. The failure of C" as a factor of TM in these two types of alloys may be ascribed that the compositiondependentmagnetic interactions and the temperature-dependent C0, which also playan important role on the martensitic transformation in these alloys. Furthermore, wedemonstrate that a proper account of the temperature and composition dependence ofC0 gives us reasonable theoretical TM(x) values in Ni2+xMn1-xGa alloys. Also in this type of Ni-rich and Mn-deficient alloys, by using the Heisenberg model in combination with the mean-field approximation, the abnormal trend of experimental magnetic transition temperature TC(x) with respect to the composition x is shown to be well captured by the theory. / QC 20110830

Diss. (sammanfattning) Stockholm : Karol. inst., 2001. / Härtill 5 uppsatser.

Results are presented from a theoretical and experimental investigation on the compressive strength of lamina reinforced and fiber reinforced composite materials when loaded parallel to the reinforcement. An analytical model which replaces the fiber reinforced composite with a laminate containing initially curved laminae has been proposed. By applying the Timoshenko beam equations to each layer of the laminate, an interlaminar shear stress analysis which can be used to predict the behavior of the laminate under compressive loading was developed. Two modes of failure are considered in the analysis, delamination and shear instability, and nonlinear shear stress-strain behavior of the laminae is included. Axial compression tests were performed on aluminum-wax laminates, boron-epoxy tubes and S-glass-epoxy tubes. In addition, torsion tests and combined compression and torsion tests were conducted on the fiber reinforced tubes. Coordinates of fibers in a boron-epoxy laminate were measured. Experimental results indicate that the aluminum-wax laminates failed by delamination and that failure of the boron-epoxy composite in compression is most likely due to shear instabIlity. In addition it was shown that the shear modulus of boron-epoxy is a function of axial compressive stress and that the fibers in a boron-epoxy composite are not parallel but contain initial curvature. Adequate correlation between theory and experiment was obtained for both lamina and fiber reinforced test results. / Ph. D.

Diante do contexto atual de grande preocupação com a preservação do meio ambiente e, ao mesmo tempo, milhares de pessoas desabrigadas devido à pobreza e às catástrofes ambientais, surge a necessidade de se estudar materiais de construção alternativos, que possam contribuir para amenizar essas questões. Com base nisso, este trabalho enfoca o emprego de tubos de papelão na construção civil pelo arquiteto japonês Shigeru Ban. Estudou-se os sistemas construtivos criados pelo referido arquiteto e as características técnicas dos tubos de papelão que este utiliza em suas obras. Foram realizados alguns ensaios técnicos preliminares para a caracterização de tubos de papelão fabricados por uma indústria brasileira, e também para se chegar à conclusão se suas características técnicas possibilitariam gerar sistemas construtivos como os das obras japonesas. Este estudo, porém, é apenas o início de muitas pesquisas que devem ser feitas até que se identifique a viabilidade de aplicação desta tecnologia no Brasil. / According to the actual context of great concern with the environment preservation and, at the same time, millions of homeless people due poverty and environmental catastrophes, arises the necessity of studying alternative construction materials, which can contribute to soften these issues. Based in this, this work focuses the use of paper tubes in the construction by the japanese architect Shigeru Ban. The construction systems created by the referenced architect and the technical characteristics of paper tubes that he uses in his works have been studied in this research. Preliminary technical tests have been done to characterize paper tubes made by a brazilian industry and to check if their technical characteristics would become possible the production of construction systems as the japanese works. This study, however, is only the beginning of several researches that will made until identify the viability of application this technology in Brazil.

Diante do contexto atual de grande preocupação com a preservação do meio ambiente e, ao mesmo tempo, milhares de pessoas desabrigadas devido à pobreza e às catástrofes ambientais, surge a necessidade de se estudar materiais de construção alternativos, que possam contribuir para amenizar essas questões. Com base nisso, este trabalho enfoca o emprego de tubos de papelão na construção civil pelo arquiteto japonês Shigeru Ban. Estudou-se os sistemas construtivos criados pelo referido arquiteto e as características técnicas dos tubos de papelão que este utiliza em suas obras. Foram realizados alguns ensaios técnicos preliminares para a caracterização de tubos de papelão fabricados por uma indústria brasileira, e também para se chegar à conclusão se suas características técnicas possibilitariam gerar sistemas construtivos como os das obras japonesas. Este estudo, porém, é apenas o início de muitas pesquisas que devem ser feitas até que se identifique a viabilidade de aplicação desta tecnologia no Brasil. / According to the actual context of great concern with the environment preservation and, at the same time, millions of homeless people due poverty and environmental catastrophes, arises the necessity of studying alternative construction materials, which can contribute to soften these issues. Based in this, this work focuses the use of paper tubes in the construction by the japanese architect Shigeru Ban. The construction systems created by the referenced architect and the technical characteristics of paper tubes that he uses in his works have been studied in this research. Preliminary technical tests have been done to characterize paper tubes made by a brazilian industry and to check if their technical characteristics would become possible the production of construction systems as the japanese works. This study, however, is only the beginning of several researches that will made until identify the viability of application this technology in Brazil.

Construction materials are exposed to different conditions along the way from the sawmill, during storage and handling, until the materials are a part of the completed construction. During this time the materials may be exposed to moisture and dirt that can cause an attack by moulds. This, in turn, can give rise to health problems for individuals staying in the building and can also be the cause of a bad smell in the building. It is therefore necessary to protect the materials during this limited period of transport, storage, and handling.In this study two construction materials were used; untreated wood and plasterboard. As a possible protection for the materials coatings based on biopolymers were made. Biopolymers are totally degradable and are relatively cheap raw materials. The biopolymers used in this study were starch from potato, protein from corn, and acetylated mono- and diglyceride. Also, fungicides that function as inhibitors for mould growth were added to the coatings.Samples of wood and plasterboard were covered with the coatings using a paint sprayer. The samples were then exposed to a spore suspension containing spores from four of the most common mould species found attacking building material. The samples were then placed in three different climates differing in temperature and humidity. The conditions were in all three cases favourable for mould growth. The samples were placed in these conditions for a month and analysis of the growth on the samples was made once a week and according to a scale with five grades.The results varied very much between the samples, even between samples treated with the same coating, but an obvious trend gave indications of that it is possible to use biopolymers as protection for construction materials. In this study the coating based on the acetylated monoglyceride showed the best properties. / Uppsatsnivå: C

自從2004年人們在實驗室上發現石墨烯以來，IV族二維半導體材料，例如石墨烯、硅烯等，由於其優異的電學、力學、光學、以及熱力學性質，受到學術界的廣泛關注。為了使IV族二維半導體材料得到廣泛引用，穩定地生長高質量的石墨烯、硅烯二維半導體材料以及透徹的理解石墨烯、硅烯二維半導體材料和襯底之間的界面特性成為至關重要的研究方向。本文對在銅表面用多環芳香烴形成石墨烯的生長機理以及石墨烯、硅烯和襯底之間的界面電子學特性進行了詳細的分析和研究。希望以此能對IV族二維半導體材料的廣泛應用具有促進作用，並且對合理的設計電子器件結構具有新的啟示。 / 首先，我們用密度泛函理論對在銅表面用多環芳香烴形成石墨烯的生長機理進行了研究。理論計算表明在銅表面多環芳香烴形成石墨烯的生長過程主要包括：（1）在銅表面的誘導下多環芳香烴脫氫，（2）這些已經脫氫的多環芳香烴在銅表面相互結合形成石墨烯。由於銅和碳的相互作用非常弱，所以在銅表面這些已經脫氫的多環芳香烴並不會進一步分解成更小的碳團簇或者單個的碳原子。因此多環芳香烴的空間幾何構型對於最終形成的石墨烯的質量以及最低成長溫度有至關重要的影響。提高生長溫度可以提升脫氫多環芳香烴的活性和熱運動性，從而提高最終生成的石墨烯的質量。六苯并苯由於具有和石墨烯相同的六重對稱性和晶格結構，所以其在低溫生長高質量石墨烯方面最具有優勢。 / 其次，我們就石墨烯和（0001）二氧化硅表面所組成的界面的電子學特性進行了研究。結果表明石墨烯在（0001）二氧化硅表面的電子學特性主要有二氧化硅表面的性質以及氫化程度決定。如果用末端為甲基的分子修飾（0001）二氧化硅表面，可以進一步減弱二氧化硅表面氧原子對石墨烯電子學特性的影響，從而提高在二氧化硅表面石墨烯的載流子遷移率。此外，當石墨烯物理吸附在二氧化硅表面上時，垂直於石墨烯和二氧化硅界面的外加電場可以調製石墨烯和二氧化硅表面的電荷轉移。這一效應可以增強雙層石墨烯之間的電場，從而有效改變雙層石墨烯的能帶結構。我們的結果有助於更好的地認識和理解石墨烯吸附在二氧化硅表面所表現的實驗現象。 / 基於以上兩個結論，我們用三亚苯合成了高質量的單層石墨烯，並對其在普通二氧化硅表面上以及十八烷基鏈三甲氧基硅烷所修飾的二氧化硅表面上，所體現出的不同電子學性質和散射機理進行了詳細研究。用三亚苯作為石墨烯的生長源可以避免傳統氣象化學沉積方法在初期成核過程中所產生的缺陷，從而得到高質量的石墨烯。電學測量表明，石墨烯在普通二氧化硅表面上的載流子遷移率約為5090 cm²V⁻¹s⁻¹。而在十八烷基鏈三甲氧基硅烷所修飾的二氧化硅表面上，其遷移率可以提高到大約9080 cm²V⁻¹s⁻¹。此外，通過這兩種不同結構的電子器件進行定量的分析和對比，我們發現在室溫下，普通二氧化硅表面上的石墨烯電子器件的平均自由程主要由電離雜質所引起的長程散射所決定，電離雜質散射源密度約為5.34×10¹¹ cm⁻²。而對於十八烷基鏈三甲氧基硅烷所修飾的二氧化硅表面上的石墨烯電子器件的平均自由程主要由甲基以及石墨烯中的缺陷和晶界所引起的共振散射所決定，共振散射源密度為9.77×10¹° cm⁻²。我們的研究結果有助於揭示通過界面修飾來提升石墨烯電子器件性能的內在原理。 / 最後， 我們對單層石墨烯和硅烯封裝在金剛石薄膜和硅薄膜結構的電子學性質，以及其隨壓強的變化，進行了系統的理論研究。結果表明，當單層石墨烯和硅烯封裝在金剛石薄膜和硅薄膜中時，通過改變壓強和堆疊結構，單層石墨烯和硅烯在狄拉克點處的能隙和電子有效質量可以被有效地調製。電子有效質量和壓強成正比。硅烯的能隙對於壓強的變化比石墨烯更加敏感。並且異質封裝結構比同質封裝結構更有利於調製石墨烯和硅烯在狄拉克點處的能隙和電子有效質量。利用封裝技術和改變壓強的方法，石墨烯和硅烯的蜂窩狀結構不會被破壞，所以其小的載流子有效質量和高的載流子遷移率將會保持。所以對於構造高性能的納米電子學器件，這種方法有明顯的應用前景。 / Group IV two Dimensional Semiconductor Materials, such as graphene, silicene and so on, composed of an atomically thin layer of carbon and silicon atoms arranged in a honeycomb lattice, have received considerable attention, as their extraordinary electronic, mechanical, optical, and thermal properties arise from their unique 2D energy dispersions, since their representive, graphene, experimentally discovered in 2004. Reliable fabrication of high-quality graphene and silicene two dimensional layers and understanding the properties of interface between graphene or silicene two dimensional layers and substrates play an indispensable role for realizing their potential applications in nanoelectronics. This thesis attempts to paint a clear picture about the growth mechanism of graphene from Polycyclic aromatic hydrocarbons (PAHs) on Cu(111) surface and interfacial electronic properties of graphene and silicene to promote application of Two Dimensional Group IV Semiconductor and shed light on rational design of functional devices. / Firstly, in order to obtain insights into the reaction mechanism, the bottom-up growth of graphene from PAHs on Cu(111) surface has been systematically analyzed by means of large-scale ab initio simulation in a density functional theory (DFT) framework. Theoretical calculation shows that the underlying growth mechanism, which mainly involves surface-mediated nucleation process of dehydrogenated PAHs rather than segregation or precipitation process of small carbon clusters decomposed from the precursors. The quality of the synthesized graphene sheets and minimum growth temperature strongly depends on the structures of PAHs as well as the molecular activities. Increasing the growth temperature will augment the activity of carbon clusters, so as to increase the probability in formation of prefect graphene sheets. Coronene, having 6-fold rotational symmetry and the same lattice as graphene, has the highest probability in forming high quality graphene, especially at relatively low growth temperature. / Secondly, the electronic properties of graphene supported by (0001) SiO₂ surface are theoretically studied using the density functional theory. It is found that the electronic attributes of graphene on (0001) SiO₂ strongly depend on the underlying SiO₂ surface properties and the percentage of hydrogen-passivation. By applying methyl to passivate oxygen-terminated (0001) SiO₂ surface one can further reduce the interaction between the graphene sheet and oxygen-terminated surface. This can improve the charge carrier mobility of graphene supported by SiO₂ substrate and reduce the influence by residual interfacial molecules. In addition, the external electric field modulates the charge transfer between graphene and the SiO₂ surface, when graphene layers are physisorbed on the oxide surface. This phenomenon will enhance the built-in electric field of bilayer graphene so as to effectively modify its band structure. Our results shed light on a better atomistic understanding of the recent experiments on graphene supported by SiO₂. / Based on the above two conclusions, the graphene/substrate interface properties and engineering of bottom-gated, large-scale triphenylene-derived graphene transistors by applying octadecyltrimethoxysilane (OTMS) self-assembled monolayers (SAM) onto the gate dielectric surface are studied. To meet the challenge that the isolated carbon monomers are likely to form defective carbon clusters with pentagons, at the initial stage of CVD graphene growth, triphenylene (C₁₈H₁₂) (pentagon-free with only C and H) was used as the solid precursor for high-quality and large-scale graphene synthesis. Transport measurements performed on back-gated graphene field-effect transistors (GFETs) with large channel lengths (~25 μm) show a carrier mobility up to ~5090 cm²V⁻¹s⁻¹ on SiO₂/Si substrate at room temperature under vacuum. Furthermore we show that in virtue of the ultrasmooth SAM surface and reduced interfacial impurity scattering as well as attenuated surface polar phonon scattering, the GFET carrier mobility on octadecyltrimethoxysilane (OTMS) passiviated SiO₂ surface is consistently improved up to ~9080 cm²V⁻¹s⁻¹, whose graphene active layer has been grown with triphenylene precursor. This makes it promising for practical applications. In addition, in comparison with the devices without interface engineering, triphenylene-derived GFETs with OTMS-SAM modified SiO₂/Si substrate exhibit the marked carrier-density-dependent field-effect mobility. Quantitative analyses reveal that at ambient temperature, the predominant scattering sources affect the carrier mean free path for graphene devices on bare SiO₂ substrates and for those on OTMS passivated SiO₂ substrates are charged impurity induced long-range scattering (~5.34×10¹¹ cm⁻² in carrier density) and resonant scattering (short-range scattering ~9.77×10¹° cm⁻² carrier in density), respectively. Our findings elucidate the underlying dominate factors for achieving the significantly improved device performance of GFETs at room temperature. / Finally, by exploiting first-principles calculations, we show that the band gap and electron effective mass (EEM) of various confined graphene and silicene (D-X/G/H-D, Si-X/S/H-Si and D-X/S/H-D) can be effectively modulated by tuning the pressure (interlayer spacing) and stacking arrangement. The electron effective mass (EEM) is proportional to the band gap. The band gap of confined silicene is more sensitive to pressure than that of confined graphene. Moreover, heterogeneous interface would be beneficial to effectively control the band gap and carrier effective masses of confined graphene and silicene. Using the confined technique and pressure, the integrity of the honeycomb structure of graphene and silicene will be preserved, so the small effective masses and high mobility of graphene and silicene will remain during compression. The tunable band gap and high carrier mobility of the sandwich structures are promising for building high-performance nanodevices. / The aforementioned four sub-topics form the mechanistic understanding of graphene growth by PAHs and interfacial electronic properties of graphene and silicene down to the molecular level. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chen, Kun. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Abstracts also in Chinese. / Abstract --- p.II / 博士學位論文摘要： --- p.VI / Acknowledgements --- p.X / Chapter Chapter 1 --- Introduction to Growth Methods and Electronic Properties of Graphene and Silicene --- p.1 / Chapter 1.1 --- Electronic Properties of Graphene --- p.2 / Chapter 1.1.1 --- The Direct Lattice and the Reciprocal Lattice --- p.2 / Chapter 1.1.2 --- Electronic Band Structure --- p.6 / Chapter 1.1.3 --- Tight-Binding Energy Dispersion --- p.7 / Chapter 1.1.4 --- Massless Dirac Fermions --- p.15 / Chapter 1.1.5 --- Carrier Density and Effective Mass --- p.21 / Chapter 1.1.6 --- The Tight-Binding Model of Bilayer Graphene --- p.24 / Chapter 1.1.7 --- The Two-Component Hamiltonian of Bilayer Graphene --- p.29 / Chapter 1.1.8 --- Trigonal Warping in Graphene --- p.32 / Chapter 1.1.9 --- Tunable Band Gap in Bilayer Graphene --- p.36 / Chapter 1.2 --- Synthesis of Graphene --- p.38 / Chapter 1.2.1 --- Exfoliation and Cleavage --- p.39 / Chapter 1.2.2 --- Thermal Decomposition of SiC --- p.40 / Chapter 1.2.3 --- Chemical Vapor Deposition of Graphene --- p.42 / Chapter 1.3 --- Electronic Properties at Graphene/Substrate Interface --- p.55 / Chapter 1.3.1 --- Graphene on SiO₂/Si Substrates --- p.56 / Chapter 1.3.2 --- Graphene on Hexagonal Boron Nitride (h-BN) --- p.60 / Chapter 1.3.3 --- Graphene on Organic Self-Assembled Monolayer (SAM) Passivation of Bared SiO₂/Si --- p.61 / Chapter 1.4 --- Synthesis and Electronic Properties of Silicene --- p.63 / Chapter 1.4.1 --- Synthesis of Silicene --- p.64 / Chapter 1.4.2 --- Electronic Properties of Silicene --- p.65 / Chapter References --- p.67 / Chapter Chapter 2 --- Introduction to Density Functional Theory --- p.75 / Chapter 2.1 --- Many-Particle Hamiltonian --- p.75 / Chapter 2.2 --- Born-Oppenheimer Approximation --- p.76 / Chapter 2.3 --- Hartree-Fock Method --- p.77 / Chapter 2.4 --- Density Functional Theory (DFT) --- p.77 / Chapter 2.4.1 --- Hohenberg-Kohn Theorems --- p.77 / Chapter 2.4.2 --- Kohn-Sham Method --- p.79 / Chapter 2.4.3 --- Kohn-Sham Equation --- p.80 / Chapter 2.4.4 --- Solution of Kohn-Sham Equation --- p.80 / Chapter 2.5 --- Electron Density Approximation --- p.80 / Chapter 2.5.1 --- Local Density Approximation (LDA) --- p.80 / Chapter 2.5.2 --- Generalized Gradient Approximation (GGA) --- p.82 / Chapter 2.5.3 --- Hybrid Functionals --- p.82 / Chapter 2.6 --- Plane Waves Expansion --- p.83 / Chapter 2.7 --- Pseudopotentials --- p.84 / Chapter 2.7.1 --- Ultrasoft Pseudopotentials (USPP) --- p.86 / Chapter 2.7.2 --- Projector Augmented Wave Potentials (PAW) --- p.87 / Chapter 2.8 --- DFT+U --- p.88 / Chapter References --- p.89 / Chapter Chapter 3 --- ab initio Study of Growth Mechanism of Graphene from Polycyclic Aromatic Hydrocarbons --- p.91 / Chapter 3.1 --- Introduction --- p.91 / Chapter 3.2 --- Experimental Results --- p.93 / Chapter 3.3 --- Calculation Method --- p.94 / Chapter 3.4 --- Calculation Results and Discussion --- p.96 / Chapter 3.5 --- Conclusion --- p.109 / Chapter References --- p.109 / Chapter Chapter 4 --- Electronic Properties of Graphene Altered by Substrate Surface Chemistry and Externally Applied Electric Field --- p.113 / Chapter 4.1 --- Introduction --- p.113 / Chapter 4.2 --- Calculation Method --- p.115 / Chapter 4.3 --- Results and Discussion --- p.116 / Chapter 4.4 --- Conclusions --- p.133 / Chapter References --- p.134 / Chapter Chapter 5 --- High Performance Devices Based on Large-Scale Triphenylene Derived Graphene and Interface Engineering --- p.138 / Chapter 5.1 --- Introduction --- p.138 / Chapter 5.2 --- Experimental Section --- p.140 / Chapter 5.3 --- Results and Discussion --- p.144 / Chapter 5.4 --- Conclusion --- p.163 / Chapter References --- p.164 / Chapter Chapter 6 --- Controllable Modulation of Electronic Properties of Graphene and Silicene by Interface Engineering and Pressure --- p.169 / Chapter 6.1 --- Introduction --- p.169 / Chapter 6.2 --- Modeling and Methods --- p.171 / Chapter 6.3 --- Results and Discussion --- p.174 / Chapter 6.4 --- Conclutions --- p.200 / Chapter References --- p.201 / Chapter Chapter 7 --- Conclusions and Future Plans --- p.204 / Chapter 7.1 --- Conclusions --- p.204 / Chapter 7.2 --- Future Plans --- p.206 / List of Publications during Ph.D. Study --- p.207

Self-Compacting Concrete (SCC) is a material which under its own self-weight flows to form and fill any shape, attains full compaction, without external energy input, to create a dense homogenous mass (based on Holton, 2003; The Concrete Society and BRE, 2005; Damtoft et al, 2008). It is, in respect to the history of concrete, a relatively new development, with its first UK application occurring in the late 1990s. Since then a significant amount of research has sought to understand its physical and structural properties, but there is a lack of a knowledge base on its practical application and performance in construction projects. Where it does exist, such research lacks robust and transparent data, particularly relating to the claimed attributes of the material (such as better surface finish, faster construction and lower overall costs). Using a combination of qualitative and quantitative research methods, this research investigates the construction practices employed when pouring SCC and presents new data on its practical applications. Interviews with a range of building contractors, ranging from multinationals to small UK businesses (SMEs), show that current perceptions of SCC limit its use to specific applications because practitioners see SCC as just another type of concrete . A critical examination of these attitudes led to the identification of three distinct scenarios for the use of SCC: 1. Reactive selection: in which a particular attribute of SCC provokes its use to solve a particular problem, often as a last minute substitution for conventional concrete the most common scenario. 2. Strategic change: in which the material is chosen on the basis of a balanced assessment of all its benefits and on the understanding that such benefits can only be attained if the contractor appreciates that there may be implications for the construction process a rarely experienced scenario. 3. Specification: in which there is complete acceptance of SCC as a method, not just as a material; a significant amount of early project involvement with knowledge holders, such as contractors and material suppliers, optimises the construction process. A rigorous work measurement study of live construction projects has made it possible to quantify the as-built costs of SCC for selected UK residential slab and multi-storey flat slab applications and compare this with the equivalent conventional concrete slab construction. On-site use of self-compacting concrete vi The results indicate that SCC can reduce construction times of structural topping layers of residential slabs by up to 73%, and has shown that SCC can also match, if not reduce, total as-built concrete placement costs in multi-storey applications. This new data will enable contractors, designers and specifiers to better understand the practical implications of using SCC for on-site applications, thereby leading to more potential instances of its early and planned specification, hence resulting in more of its full benefits being realised.

<p>This exam report has been developed in association with Strangbetong AB, Sweden.</p><p>The natural gravel that is being used as fine aggregate for concrete production today is an ending natural recourse and the Swedish government has decided to strongly reduce the extraction from the year of 2020. The only reasonable replacement is aggregates from crushed rocks but this material has other properties than natural aggregates. The concrete manufacturers now have to learn how to use these new fine aggregates in a cost effective way in order to ensure the quality of their concrete production.</p><p>In this project, crushed aggregates and combination of crushed and natural aggregates have been tested with existing formulas for fresh concrete. The two parameters yield stress and plastic viscosity have been measured which gives a good description of the workability of the fresh concrete. Different methods to make measurements on the dry fine aggregates, has also been tested, to find out if there is any correlations between these parameters and the parameters from the measurement on the fresh concrete.</p>

QC20100709