Kesan penggunaan koswer multimedia animasi visual terhadap pencapaian pelajar dalam mata pelajaran matematik

Ramai pelajar yang bermasalah dalam topik Pelan dan Dongakan. Ini kerana pelajar sukar untuk membayangkan objek yang tersembunyi melalui proses pengajaran dan pembelajaran (P&P) secara konvensional. Penyelidik telah membangunkan satu koswer multimedia animasi visual dalam topik Pelan dan Dongakan dengan menerapkan kesemua elemen-elemen yang dapat membantu meningkatkan kemahiran visual iaitu elemen animasi, video, audio, grafik dan teks. Seterusnya, kajian kuasi eksperimental ini turut dijalankan bertujuan untuk mengetahui kesan penggunaan koswer multimedia animasi visual terhadap pencapaian pelajar bagi mata pelajaran Matematik di sekolah menengah. Ujian Pra dan Ujian Pos digunakan untuk melihat perbezaan pencapaian yang signifikan selepas menggunakan koswer multimedia animasi visual yang menggunakan teori Kognitif Visual Wiley. Responden yang terlibat dalam kajian ini ialah seramai 40 orang pelajar Tingkatan Lima yang dibahagikan kepada dua kumpulan iaitu kumpulan rawatan dan kumpulan kawalan yang dipilih daripada sebuah sekolah di daerah Batu Pahat, Johor. Hasil analisis menunjukkan peningkatan skor min markah bagi pelajar kumpulan rawatan. Hasil analisis ujian-t (paired-sample-t-test) membuktikan bahawa wujudnya perbezaan skor min markah yang signifikan di antara markah ujian pra dan markah ujian pos bagi kumpulan rawatan. Oleh itu, terdapat perbezaan yang signifikan di antara skor min markah ujian pra dan ujian pos bagi pelajar kumpulan rawatan selepas menggunakan koswer multimedia animasi visual. Manakala instrumen soal selidik yang digunakan untuk melihat tahap penerimaan pelajar selepas menggunakan koswer multimedia animasi visual berdasarkan tiga aspek iaitu aspek isi kandungan, aspek interaksi dan aspek persembahan telah memeperolehi skor min yang tinggi bagi ketiga-tiga aspek tersebut. Dapatan kajian ini menggambarkan penggunaan koswer multimedia animasi visual dapat membantu meningkatkan pencapaian Matematik di dalam bilik darjah terutama yang tidak melibatkan pengiraan

Innovative Structural Materials and Sections with Strain Hardening Cementitious Composites

abstract: The motivation of this work is based on development of new construction products with strain hardening cementitious composites (SHCC) geared towards sustainable residential applications. The proposed research has three main objectives: automation of existing manufacturing systems for SHCC laminates; multi-level characterization of mechanical properties of fiber, matrix, interface and composites phases using servo-hydraulic and digital image correlation techniques. Structural behavior of these systems were predicted using ductility based design procedures using classical laminate theory and structural mechanics. SHCC sections are made up of thin sections of matrix with Portland cement based binder and fine aggregates impregnating continuous one-dimensional fibers in individual or bundle form or two/three dimensional woven, bonded or knitted textiles. Traditional fiber reinforced concrete (FRC) use random dispersed chopped fibers in the matrix at a low volume fractions, typically 1-2% to avoid to avoid fiber agglomeration and balling. In conventional FRC, fracture localization occurs immediately after the first crack, resulting in only minor improvement in toughness and tensile strength. However in SHCC systems, distribution of cracking throughout the specimen is facilitated by the fiber bridging mechanism. Influence of material properties of yarn, composition, geometry and weave patterns of textile in the behavior of laminated SHCC skin composites were investigated. Contribution of the cementitious matrix in the early age and long-term performance of laminated composites was studied with supplementary cementitious materials such as fly ash, silica fume, and wollastonite. A closed form model with classical laminate theory and ply discount method, coupled with a damage evolution model was utilized to simulate the non-linear tensile response of these composite materials. A constitutive material model developed earlier in the group was utilized to characterize and correlate the behavior of these structural composites under uniaxial tension and flexural loading responses. Development and use of analytical models enables optimal design for application of these materials in structural applications. Another area of immediate focus is the development of new construction products from SHCC laminates such as angles, channels, hat sections, closed sections with optimized cross sections. Sandwich composites with stress skin-cellular core concept were also developed to utilize strength and ductility of fabric reinforced skin in addition to thickness, ductility, and thermal benefits of cellular core materials. The proposed structurally efficient and durable sections promise to compete with wood and light gage steel based sections for lightweight construction and panel applicationDissertation/ThesisDoctoral Dissertation Civil and Environmental Engineering 201

Towards a comprehensive framework for foam concrete mix design

Foam concrete is a low-density, highly workable cementitious material, created by blending a fine-aggregate paste with a foaming agent. Properties of foam concrete suggest potential for commercial exploitation of the material in a wide variety of applications and markets. However, reliably designing a foam concrete mix to a particular specification has proved a difficult challenge and a barrier to more widespread usage. This thesis builds a comprehensive framework for foam concrete mix design. A strategic set of mixes, across a broad range of densities, cementitious densities, and cementitious blends, is evaluated for an extensive array of properties: compressive strength, density, slump flow, segregation, modulus of elasticity, Poisson’s ratio, crushing behaviour, creep, drying shrinkage, capillary water uptake, moisture storage, moisture movement, thermal conductivity, freeze-thaw resistance, and air-void distribution. Critical and previously neglected engineering properties are quantified and characterized. A proposed model assimilates interrelated trends, to explain observed behaviour of foam concrete in plastic, curing, and hardened phases at a micromechanical scale. Knowledge is summarized in a series of mix design guides, to assist in developing appropriate solutions for given applications, with less reliance on trial-and-error and speculation. Finally, this study lays a foundation for a systematic and methodologically consistent approach to future foam concrete research

Properties and microstructure of pre-formed foamed concretes

In construction buildings, use of thermal insulating materials is essential and beneficial not only by reducing the cooling/heating cost and the structural element sizes but also reducing the pollution of the environment which results from heavy use of fuel. Foamed concrete is a lightweight material. In this research, by using the preformed foam method, foamed concrete mixes with/without lightweight aggregate (LWA), which are suitable for semi-structural or structural purposes with good insulation and durability properties, were designed and produced. Then, their behaviour and the effect of microstructure on their macro properties were established. As a result, the mechanical, thermal and permeation performance as well as damage behaviour of foamed concrete, associated with changes in its microstructure that result from inclusion of superplasticizer, additives (silica fume and fly ash) and LWA, were investigated. The results showed that, for a given density, although the additives in combination led to increased void numbers, both void size and connectivity were reduced by preventing their merging and this resulted in a narrow void size distribution. As a result, the mineral admixtures (silica fume and fly ash) and superplasticizer combination provides improvement in the strength properties of foamed concrete. In addition, due to their making the cement paste denser and less porous, addition of additives and superplasticizer in combination led to slightly increased thermal conductivity in the dry state. However, owing to reduced water absorption, the thermal conductivity in the saturated state was slightly lower for mixes with additives than conventional mixes. Adding additives (individually or in combination) helped in reducing the water absorption, sorptivity and permeability of foamed concrete. However, inclusion of LWA resulted in increased sorptivity and permeability compared to the same density mixes, conventional or with additives in combination. From elasticity, fracture and fractal points of view, it was found that brittleness increases with additives while it reduces with inclusion of LWA. However, at a micro level, less damage occurred in mixes with LWA and the bond microcracks percentage increased with inclusion of additives. Finally, although the findings of this study are encouraging for the potential of using modified foamed concrete with additives in semi-structural and structural applications, it was recommended that using it in reinforced structural elements such as beams, columns, slabs and reinforced walls or load bearing masonry walls needs to be experimentally examined and evaluated

Development of alkali-activated foamed materials combining both mining waste mud and expanded granulated cork

In Portugal, the significant amount of mine waste mud from tungsten mining operations has led to growing concerns about their ecological and environmental impacts such as the occupation of large areas of land, generation of powder and the contamination of surface and underground water. Furthermore, natural by-products in general, and natural cork particles in particular, have been used to manufacture new materials which not only provide good thermal insulation but also have a limited impact on the environment and a lower cost. Alkali-activated foamed materials have been introduced in the field of alkali-activated materials which have been produced from different raw and waste materials. It has been proposed as a new idea that involves the production of lightweight materials, thus combining the performance and the benefits of energy-saving (Carbon footprint) with the reduction of the cradle-to-gate emission obtained. Besides, in order to reduce the density of the alkali-activated materials holes or lightweight aggregates can be added for such purposes. Therefore, in this research, novel alkali-activated lightweight foamed materials (AALFM) from a combination of tungsten mine waste mud (TWM), waste glass (WG), and metakaolin (Mk) using alkali activators solution of Sodium Silicate (SS) and Sodium Hydroxide (SH) was developed and combined with natural expanded granulated cork (EGC) using aluminium powder (Al) as a foaming agent. The objective of this study is to develop a new alkali-activated foamed tungsten-based binder/mortar and to characterize the cork waste composite made from this binder/mortar and natural granulated aggregates (EG-Cork). Cork, which is the exterior bark of Quercus suber L., a natural, organic, and lightweight plant tissue with a high dimensional stability substance. Physical properties of tungsten-based alkali-activated binder/mortar such as bulk density, thermal conductivity and pore sizes distribution were provided. The formulations of the alkali-activated binders are based on a combination of tungsten waste mud (TWM), waste glass (WG), and metakaolin (Mk). The mechanical and thermal properties of alkali-activated foamed materials produced were then tested. The research work includes three main phases. The first part shows the feasibility to produce new improved lightweight foamed alkali-activated materials using Panasqueira tungsten waste mud (TWM) as major raw material incorporating expanded granulated cork (EGC). During this preliminary study, a series of mixes containing mining waste mud, milled waste glass, metakaolin and Ordinary Portland Cement, in different proportions, were prepared. The influence on porosity, density, and compressive strength of incorporating granulated expanded cork at different percentages was first studied with potential applications in artistic, architectural, and historical heritage restoration. The second part investigates the influence of different precursors’ particle sizes on the physical and mechanical properties, such as density, porosity, expansion volume, and pore size by image analysis. The design and development of tungsten-based alkali-activated foams (AAFs) were studied systematically. Moreover, the manufactured AAFs with enhanced compressive strength from non-calcined tungsten waste mud (raw material) by changing the precursor particle sizes showed results of the same level or even higher as other research results obtained with fly ash and MK. The third part of the research investigates the effect of the incorporation of expanded granulated cork (EGC) to produce alkali-activated lightweight foamed materials (AALFM) with thermal properties. The findings indicate that experimental research on different combinations of raw materials particularly tungsten mining waste mud (TMWM) contribute to the development of alkali-activated materials (AAMs) and alkali-activated foamed materials (AAFMs). These new improved materials can be used as building materials with enhanced properties such as compressive strength, density, thermal conductivity, and fire resistance. This doctoral research contributes to a sustainable development by promoting the complete recycling and use of mining wastes as construction materials.Em Portugal, a quantidade significativa de lamas residuais provenientes das operações de mineração de tungsténio, tem gerado preocupações crescentes relativamente aos impactos ecológicos e ambientais, tais como, ocupação de grandes áreas de terreno, libertação de poeiras, e a contaminação de águas superficiais e subterrâneas. Nesta pesquisa, um novo material espumoso leve obtido por ativação alcalina (AALFM) de lamas residuais da mina de tungsténio (TWM) foi desenvolvido, utilizando pó de alumínio (Al) como agente de formação de espuma e, ainda, combinado com cortiça granulada expandida natural (EGC). O trabalho de pesquisa comtemplou três fases principais. A primeira parte demonstra a viabilidade de produção de novos materiais expandidos ativados alcalinamente utilizando lamas residuais das minas de tungsténio da Panasqueira (TWM) como principal matéria-prima e, incorporando cortiça granulada expandida (EGC), com aplicações potenciais na restauração de património artístico, arquitetónico e histórico. Neste estudo preliminar, foram preparados conjuntos de misturas, contendo lamas residuais, resíduo de vidro moído, metacaulino e cimento Portland, em diferentes proporções. Em primeiro lugar, foi estudada a influência na porosidade, densidade e resistência à compressão da incorporação de cortiça expandida granulada em diferentes percentagens. A segunda parte investiga o projeto e o desenvolvimento de ligantes /argamassas espumosas ativadas alcalinamente com lamas das minas de tungsténio, utilizando três tamanhos de partícula de diferentes. As propriedades físicas e mecânicas, densidade, porosidade, volume de expansão e tamanho dos poros, foram estudados de forma sistemática. Além disso, foi também estudado o aprimoramento da resistência à compressão de espumas ativadas alcalinamente (AAFs), alterando os tamanhos das partículas precursoras. A terceira parte da investigação investiga o efeito da incorporação da cortiça granulada expandida (EGC) na produção de espumas leves ativadas alcalinamente (AALFM) nas suas propriedades térmicas. Os materiais espumosos ativados alcalinamente inserem-se no campo dos materiais obtidos por ativação alcalina, os quais têm sido produzidos a partir de diferentes matérias-primas e resíduos. Foi proposto como uma ideia nova que envolve a produção de materiais leves, combinando assim o desempenho e os benefícios da poupança de energia (pegada de carbono) com a redução da emissão “cradle-to-gate” obtida. Além disso, a fim de reduzir a densidade dos materiais ativados alcalinamente, podem ser adicionados orifícios ou agregados leves para esse fim. Os resultados dos estudos experimentais permitem desenvolver diferentes tipos de materiais, utilizando resíduos de minas como matéria-prima. Este novo material produzido pode ser usado como materiais de construção com propriedades aprimoradas, como resistência à compressão, densidade, condutividade térmica e resistência ao fogo. Esta investigação de doutoramento contribui para o desenvolvimento sustentável, promovendo a reciclagem completa e a utilização de resíduos de mineração como materiais de construção.This doctoral research work was conducted at the University of Beira Interior (UBI) and partially financed by the following grants: A Doctoral Incentive Grant (BID) – Santander-Totta/UBI research grants ‘‘Bolsa BID/ICI-FE/Santander Universidade – UBI/2017”; Portuguese national funds through FCT – Foundation for Science and Technology, IP, within the research unit C-MADE, Centre of Materials and Building Technologies (CIVE-Central Covilhã-4082), University of Beira Interior, Portugal and the European Commission Horizon2020, MARIE Skłodowska-CURIE Actions, Research, and Innovation Staff Exchange (RISE), - “REMINE- Reuse of Mining Waste into Innovative Geopolymeric-based Structural Panels, Precast, Ready Mixes and in-situ Applications”, project no. 645696, Coordinator: University of Beira Interior (PT), comprising three months secondments abroad at the company ALSITEK Limited (Ltd), Peterborough, United Kingdom (UK)