Improving Concrete Sustainability and Durability by Optimization of Aggregate Particle Packing and Use of Microfine Fillers PDF Download

Author: Majella Anson-Cartwright
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: FIB – International Federation for Structural Concrete
Publisher: FIB - Féd. Int. du Béton
ISBN: 2980676225
Category : Technology & Engineering
Languages : en
Pages : 650

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Author: Miras Mamirov
Publisher:
ISBN:
Category : Pavements, Concrete
Languages : en
Pages : 109

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Book Description
The main objective of this study was to evaluate the effect of aggregate particle packing optimization and cement reduction on Nebraska slip-form pavement concrete performance. A literature review was conducted to examine different aggregate optimization tools, quality control tests, and historical data of Nebraska Department of Transportation (NDOT) mixtures. It was found that the Modified Toufar Model has good potential in optimizing particle packing and predicting packing degrees. The combined void content test was found to be useful to experimentally justify optimized aggregate gradations. Two specific pavement concrete workability tests, i.e., the Box Test and the VKelly Test, were used to evaluate the effect of cement reduction and optimized aggregate gradation on pavement concrete workability. The Box Test ranking was modified to provide a more detailed and objective evaluation. Analysis of different aggregate combinations has shown that experimental packing from the combined void content test has a high correlation with estimated packing from the Modified Toufar Model. Results showed that when the optimized aggregate gradation is used, cement content can be effectively reduced by up to 1.0 sack (94 lb/yd3) without compromising the fresh properties, mechanical properties, and permeability. Based on the results of free and restrained shrinkage, it was justified that shrinkage and cracking potential can be reduced in optimized concrete mixtures. Freeze/thaw resistance can be slightly improved with optimized mixtures. A mix design improvement procedure considering both theoretical and experimental packing and the minimum excess paste-to-aggregate ratio can be used to design concrete with an optimum cement content.The main objective of this study was to evaluate the effect of aggregate particle packing optimization and cement reduction on Nebraska slip-form pavement concrete performance. A literature review was conducted to examine different aggregate optimization tools, quality control tests, and historical data of Nebraska Department of Transportation (NDOT) mixtures. It was found that the Modified Toufar Model has good potential in optimizing particle packing and predicting packing degrees. The combined void content test was found to be useful to experimentally justify optimized aggregate gradations. Two specific pavement concrete workability tests, i.e., the Box Test and the VKelly Test, were used to evaluate the effect of cement reduction and optimized aggregate gradation on pavement concrete workability. The Box Test ranking was modified to provide a more detailed and objective evaluation. Considering one of the goals of the study was to maximize the use of local materials, locally available cementitious materials and aggregates from East and West Nebraska were selected. Analysis of different aggregate combinations has shown that experimental packing from the combined void content test has a high correlation with estimated packing from the Modified Toufar Model. Results also demonstrated that the current aggregate combination is not the optimum gradation and can be improved. The experimental program included in this study consisted of three Phases. Phase 1 focused on obtaining promising aggregate blends by maintaining the standard cement content (564 lb/yd3, 335 kg/m3). Fresh concrete properties were the main criteria to select promising blends. Phase 2 included an evaluation of performance of pavement concrete with cement content reduced by 0.5 sack (47 lb/yd3, 28 kg/m3) steps for other reference and optimized aggregate blends. Results justified that when optimum gradation is used, cement could be reduced up to 94 lb/yd3 (56 kg/m3). Phase 3 is the performance evaluation phase, which included evaluating the reference mix and selected promising mixes for setting time, modulus of elasticity, free shrinkage, restrained shrinkage, and freeze/thaw resistance. Mixtures with reduced cement and optimized aggregate gradation have shown improved freeze/thaw resistance and lower shrinkage rate. Finally, a mix design improvement procedure incorporating theoretical and experimental particle packing and using excess paste-to-aggregates ratio as the control parameter was proposed. To sum up, the study has justified that the Modified Toufar Model and the combined void content test can be useful tools in aggregate gradation optimization. In order to evaluate workability of pavement concrete more accurately, the Box Test ranking was modified based on image analysis of surface and edge quality. It was also proved that mixtures with reduced cement content and optimized aggregate gradation perform better in terms of freeze/thaw resistance and shrinkage.

Author: Jiajian Chen
Publisher:
ISBN: 9781361279656
Category :
Languages : en
Pages :

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This dissertation, "Use of Fillers to Improve Packing Density and Performance of Concrete" by Jiajian, Chen, 陈嘉健, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: It is generally very difficult to produce high-performance concrete having concurrently high strength, high durability, high workability and high dimensional stability. This is because low water content is required to achieve high strength and high durability, high water content and large paste volume are required to achieve high workability, and low cement content and small cement paste volume are required to achieve high dimensional stability. One way of overcoming such conflicts is to add fillers to increase the packing density of concrete so that the amounts of water and paste needed to fill voids could be reduced. In this study, the use of fillers to improve the packing density and performance of concrete is investigated by measuring the packing density and overall performance of cement paste and concrete mix samples with different types and amounts of fillers added. The packing density results revealed that finer fillers are more effective in improving the packing density for releasing more excess water (water in excess of that needed to fill voids) to lubricate the solid particles. Moreover, triple blending of two fillers of different fineness with cement can better increase the packing density than double blending of just one filler with cement. On the other hand, the workability, strength and dimensional stability results showed that the addition of condensed silica fume, fly ash microsphere or superfine cement could improve the overall workability-strength performance of cement paste through increasing the packing density of the cementitious materials, while the addition of condensed silica fume, fly ash or limestone fine coeuld improve the overall dimensional stability-strength performance of concrete through decreasing the cement content or cement paste volume. Hence, the incorporation of fillers to improve the packing density opens up the possibility of using ultra-low W/CM ratio and ultralow paste volume to produce an ultrahigh-performance concrete. However, despite increases in packing density and excess water, the addition of fillers does not always improve the workability. Generally, the addition of fillers would more significantly increase the workability at low W/CM ratio and less significantly increase or even decrease the workability at high W/CM ratio. In-depth analysis indicated that both the excess water and solid surface area have great effects on the rheology. In this regard, a parameter called water film thickness (WFT), which is defined as the average thickness of water films coating the solid particles and may be determined as the excess water to solid surface area ratio, is proven to be the key factor governing the rheology. Therefore, it should be the WFT rather than the packing density that should be maximized in the mix design of high-performance concrete. The addition of fillers would increase both the excess water and solid surface area. If the proportional increase in excess water is larger than the proportional increase in solid surface area, the WFT would increase, but if otherwise, the WFT would decrease. To increase the WFT, a filler that can significantly increase the packing density

Author: Subhasis Pradhan
Publisher: Springer Nature
ISBN: 9819975166
Category :
Languages : en
Pages : 288

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Author: Paul O. Awoyera
Publisher: Woodhead Publishing
ISBN: 0128241063
Category : Technology & Engineering
Languages : en
Pages : 499

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Book Description
The Structural Integrity of Recycled Aggregate Concrete Produced with Fillers and Pozzolans presents a review on the use of by-products, fillers and pozzolanic materials in the development of concrete, with an emphasis on structural integrity. The volume is broken down into key sections, including a review of the types of materials that are used as latent hydraulic supplements, fillers and pozzolans for making recycled aggregate concrete, rheology and hydration phenomenon, the mechanical and microscale nature of concrete, and the impact of fillers and pozzolans on the workability of concrete with case studies. Durability and strength development are also discussed. The final section looks at issues such as performance effect, LCA, environmental impact, sustainability and cost benefit analysis. With detailed case studies throughout, this volume will provide useful information for all stakeholders involved in the built environment, including materials scientists, civil engineers, builders, architects and policymakers. Identifies several potential by-products, fillers and pozzolans for the development of durable concrete Acts as a guidebook for constructors and researchers working in the broad field of material science, engineering and in-situ application Presents the durability properties of concrete made of by-products, fillers and pozzolans

Author: Siti Dalila Ruslan
Publisher:
ISBN:
Category : Aggregates (Building materials)
Languages : en
Pages : 45

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Author: Leonid Dvorkin
Publisher: CRC Press
ISBN: 1000045250
Category : Technology & Engineering
Languages : en
Pages : 194

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Book Description
The use of concrete and mortar containing coal fly ash, blast furnace slag, and other dispersed technogenic materials is one of the major areas of potential resource savings and improving the environmental efficiency and sustainability of construction. Improving Concrete and Mortar using Modified Ash and Slag Cements presents the results of a study of high-tech concrete on composite Portland cement and slag Portland cement. It explains the possibility of significantly improving the properties of cements and concrete with the introduction of superplasticizers and hardening activators. Features: Describes how additives can reduce costs and lead to more environmentally sustainable production Explains the possibility of obtaining high-tech concrete with a high content of ash, slag, and clinker kiln dust Presents the possibility of significant reductions of the most energy-intensive component of cements Examines the calculated dependences for predicting the technical properties of concrete saturated with dispersed technogenic products Explains the methods of calculating the composition of concrete with specified properties of low-clinker cements Suitable for civil and structural engineers as well as for specialists working in the field of concrete technology, students of civil engineering, and researchers of new construction technologies, this book allows readers to understand new and sustainable ways to improve the properties of concrete and mortar by utilizing additives.

Author: Ali Akbar Ramezanianpour
Publisher: Springer Science & Business Media
ISBN: 3642367216
Category : Science
Languages : en
Pages : 345

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Book Description
The aim of this book is to present the latest findings in the properties and application of Supplementary Cementing Materials and blended cements currently used in the world in concrete. Sustainability is an important issue all over the world. Carbon dioxide emission has been a serious problem in the world due to the greenhouse effect. Today many countries agreed to reduce the emission of CO2. Many phases of cement and concrete technology can affect sustainability. Cement and concrete industry is responsible for the production of 7% carbon dioxide of the total world CO2 emission. The use of supplementary cementing materials (SCM), design of concrete mixtures with optimum content of cement and enhancement of concrete durability are the main issues towards sustainability in concrete industry.

Author: Adel Baghdady
Publisher:
ISBN:
Category :
Languages : en
Pages : 22

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This paper studies the effectiveness of applying value engineering to actual concrete mixtures. The study was conducted in the State of Qatar on a number of strategic construction projects with international engineering specifications for the 2022 World Cup projects. The study examined the concrete mixtures of Doha Metro project and the development of KAHRAMAA's (Qatar Electricity and Water Company) Abu Funtas Strategic Desalination Plant, in order to generally improve the quality and productivity of ready-mixed concrete used in construction and hydraulic projects. The application of value engineering to such concrete mixtures resulted in the following: • Improving the quality of concrete mixtures and increasing the durability of buildings in which they are used; • Reducing the waste of excess materials of concrete mixture, optimizing the use of resources, and enhancing sustainability; • Reducing the use of cement, thus reducing CO2 emissions which ensures the protection of environment and public health; • Reducing actual costs of concrete mixtures and, in turn, reducing the costs of construction projects; and • Increasing the market share and competitiveness of concrete producers. This research shows that applying the methodology of value engineering to ready-mixed concrete is an effective way to save around 5% of the total cost of concrete mixtures supplied to construction and hydraulic projects, improve the quality according to the technical requirements and as per the standards and specifications for ready-mixed concrete, improve the environmental impact, and promote sustainability.