Nanotechnology Applied To High Volume Fly Ash Concrete And Its Resistance To Freeze Thaw Damage
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| Author | : Sen Du |
| Publisher | : |
| Total Pages | : 226 |
| Release | : 2020 |
| Genre | : Fly ash |
| ISBN | : |
Partially replacing cement with fly ash in concrete is an effective approach for reusing fly ash. High-volume fly ash (HVFA) concrete contains more fly ash than cement and exhibits many advantages including low hydration heat, low shrinkage, and reduced production cost. In this context, HVFA concrete has been successfully used in the field, such as mass concrete and structural concrete. However, some drawbacks are hindering its wider acceptance, including low early-age strengths and low freezing-thawing (F-T) resistance.This dissertation firstly optimizes the mix design of HVFA mortar through a statistical design of experiment, aimed at obtaining the best performance in the mechanical properties. In the HVFA system that adopted the optimized mix design, a hypothesis is proposed that approaches that can improve the transport properties, matrix's microstructure properties, and the interfacial transition zone (ITZ) properties could finally benefit the F-T resistance of HVFA concrete. Nanotechnology, including nanoscience and nanoengineering, is applied to investigate the hydration characteristics of fly ash and modify the F-T durability of HVFA concrete.For transport properties, some chemical admixtures are admixed into HVFA mortars, the dosages of which are optimized based on the performance of water sorptivity and mechanical properties. Pore structure at nanoscale and microscale are investigated based on its close relationship with transport properties. Graphene oxide (GO), as a promising nanomaterial in cement-based material, is added into HVFA concrete to enhance its microstructure. The modification mechanisms of GO on HVFA mixture are studied. Focusing on the ITZ, GO and nanosilica (NS)-contained paste slurry are applied to coat the coarse aggregate. The effectiveness of this approach is verified through images analysis. HVFA concretes with the best performance in the aforementioned three sections are subjected to further F-T testing. A four-phase sphere model is proposed for HVFA concrete to predict the change in dynamic modulus of elasticity during F-T cycles. Future research may include the life-cycle assessment of HVFA concrete in the context of employing nanotechnology. Besides, the F-T durability of HVFA concrete in the presence of deicers should be researched given the fact that more deicers are applied on concrete infrastructures.
| Author | : |
| Publisher | : |
| Total Pages | : 162 |
| Release | : 1992 |
| Genre | : Coal-fired power plants |
| ISBN | : |
| Author | : |
| Publisher | : |
| Total Pages | : 134 |
| Release | : 1992 |
| Genre | : Coal ash |
| ISBN | : |
| Author | : Chengsheng Ouyang |
| Publisher | : |
| Total Pages | : 70 |
| Release | : 1997 |
| Genre | : Concrete |
| ISBN | : |
The freeze-thaw resistance of concretes was studied. Nine concrete mixes, made with five cements and cement-Class C fly ash combinations, were exposed to freeze-thaw cycling following 110 to 222 days of moist curing. Prior to the freeze-thaw cycling, the specimens were examined by a low-vacuum scanning electron microscope (SEN) for their microstructure. The influcence of a wet/dry treatment was also studied. Infilling of ettringite in entrained air voids was observed in the concretes tested. The extent of the infilling depends on the period of moist curing as well as the wet/dry treatment. The concretes with 15% Class C fly ash replacement show more infilling in their air voids. It was found that the influence of the infilling on the freeze-thaw durability relates to the air spacing factor. The greater the spacing factor, the more expansion under the freeze-thaw cycling. The infilling seems to decrease effective air content and to increase effective spacing factor. The infilling also implies that the filled air voids are water-accessible. These might lead to concrete more vulnerable to the freeze-thaw attack. By combining the above results with field observations, one may conclude that the freeze-thaw damage is a factor related to premature deterioration of PCC pavements in Iowa.
| Author | : V. Mohan Malhotra |
| Publisher | : |
| Total Pages | : 120 |
| Release | : 2005 |
| Genre | : Fly ash |
| ISBN | : 9780973150728 |
| Author | : Tijani Mohammed |
| Publisher | : |
| Total Pages | : 68 |
| Release | : 2021 |
| Genre | : Aggregates (Building materials) |
| ISBN | : |
Concrete industry is one of the main industries using large proportion and volume of our natural resources. Ordinary Portland Cement is an important source for the emission of carbon dioxide into the atmosphere because of burning fuel and raw materials' decomposition during the production process of cement. Due to the increasing demand in concrete, one of the most effective and reliable ways to reduce the negative impact on the environment in the concrete industry is through the use of waste and by-product materials such as aggregates and ordinary portland cement replacement in concrete. The prospect of producing structural lightweight concrete using large volume of waste materials and by-products is investigated in this current study. The lightweight material used as coarse aggregate comprised of expanded shale and expanded clay. While the waste and by-product material comprised of a high volume (50% and 70%) of type C and type F fly ash, as replacement for cement by volume. The mechanical properties such as compressive strength, split-tensile strength, flexural strength, modulus of elasticity and drying shrinkage for up to 28 and 56 days are investigated as well as slump and unit weight for fresh density. The durability properties such as abrasion resistance, water absorption, resistance to chloride ion penetration and freeze and thaw resistance are also investigated. All lightweight concrete containing 50% fly ash class C and F replacement showed adequate strength in the mechanical properties. While lightweight concrete with 70% fly ash both class C and F exhibited strength lost compared to other concrete samples. Test results showed that the early ages of drying shrinkage of ordinary Portland cement and fly ash are similar but with the growth rate of drying shrinkage in OPC, it is expected for concrete incorporated with fly ash to exhibit good resistance to drying shrinkage. Test results also indicated that, concrete incorporated with fly ash showed good resistance to chloride ion penetration and there was no significant difference in abrasion for either OPC or fly ash incorporated concretes. There was significant difference in water absorption of the concrete containing fly ash. However, concretes with fly ash performed poorly and could not resist exposure to freeze and thaw mechanism especially concretes incorporated with 70% fly ash F.
| Author | : Carmen Andrade |
| Publisher | : Springer |
| Total Pages | : 196 |
| Release | : 2014-10-30 |
| Genre | : Technology & Engineering |
| ISBN | : 3319099213 |
This book presents key advances in the modeling of reinforcement corrosion and concrete durability. It also examines various further aspects of reinforcement corrosion and concrete durability, striking a balance between modeling and testing. Particular attention is paid to innovative treatments for avoiding deterioration, and to methods for modeling performance in a real environment. Some basic aspects related to non-destructive testing techniques are also discussed. Deterioration-related topics addressed in the book include the basis for modeling alkali-silica reactions, chloride diffusion and the development of concrete microstructure; measurement-related topics include cathodic protection, polarization resistance and resistivity. A combined approach using the AFM technique and polarization measurements is examined, and the relation between cracking and corrosion and the treatment of concrete with hydrophobes or innovative products such as hydrotalcite is also discussed.
| Author | : Dr. SS. Asadi & Dr. Vennam Swathi |
| Publisher | : Laxmi Book Publication |
| Total Pages | : 107 |
| Release | : 2024-01-20 |
| Genre | : Art |
| ISBN | : 1304796221 |
When infrastructure is built quickly, development occurs. Concrete is the go-to material for construction projects. Manufacturing cement is a significant contributor to atmospheric carbon dioxide. Using carbon-neutral materials like crimson mud or powdered snail shells can reduce cement's carbon dioxide emissions by half. As an adaptable alternative to traditional concrete, HVFA concrete has many uses. Long-lasting and useful in Plain Cement Concrete (PCC) projects, fly ash also enhances concrete's workability. The positive effects of fly ash on the environment, such as lower carbon dioxide emissions, are not new. Adding fly ash to concrete increases its strength and segregation, which reduces its price and makes it simpler to pump.
| Author | : K. Wesche |
| Publisher | : CRC Press |
| Total Pages | : 298 |
| Release | : 2004-03-01 |
| Genre | : Architecture |
| ISBN | : 0203626419 |
This book is a state-of-the-art report which documents current knowledge on the properties of fly ash in concrete and the use of fly ash in construction. It includes RILEM Recommendations on fly ash in concrete and a comprehensive bibliography including over 800 references.
| Author | : Dietmar Lutze |
| Publisher | : Verlag Bau+Technik |
| Total Pages | : 176 |
| Release | : 2013-03-20 |
| Genre | : Technology & Engineering |
| ISBN | : 3764005378 |
When used as an addition and binder component, fly ash has become an indispensable construction material for many concrete applications. The conditions produced in power stations when firing fine pulverized coal result in the formation of a reactive, flour-fine, pozzolanic mineral material from the accompanying rock in the coal. Owing to its specific characteristics it has a positive impact on the properties of fresh and hardened concrete and facilitates cost-effective production of high-grade, durable concretes. The authors of this handbook have combined the latest discoveries from the field of research with practical experience of the use and effects of fly ash in concrete. This handbook provides the necessary information and makes interesting suggestions for selective use of fly ash in concrete.
