International RILEM Conference on Materials, Systems and Structures in Civil Engineering Conference segment on Service Life of Cement-Based Materials and Structures

Vol. 2O volume I encontra-se disponível em: http://hdl.handle.net/1822/4341

Proceedings of the International RILEM Conference Materials, Systems and Structures in Civil Engineering segment on Service Life of Cement-Based Materials and Structures

Vol. 1O volume II encontra-se disponível em: http://hdl.handle.net/1822/4390

Microwave material characterization of alkali-silica reaction (ASR) gel in cementitious materials

Since alkali-silica reaction (ASR) was recognized as a durability challenge in cement-based materials over 70 years ago, numerous methods have been utilized to prevent, detect, and mitigate this issue. However, quantifying the amount of produced ASR byproducts (i.e., ASR gel) in-service is still of great interest in the infrastructure industry. The overarching objective of this dissertation is to bring a new understanding to the fundamentals of ASR formation from a microwave dielectric property characterization point-of-view, and more importantly, to investigate the potential for devising a microwave nondestructive testing approach for ASR gel detection and evaluation. To this end, a comprehensive dielectric mixing model was developed with the potential for predicting the effective dielectric constant of mortar samples with and without the presence of ASR gel. To provide pertinent inputs to the model, critical factors on the influence of ASR gel formation on dielectric and reflection properties of several mortar samples were investigated at R, S, and X-band. Effects of humidity, alkali content, and long-term curing conditions on ASR-prone mortars were also investigated. Additionally, dielectric properties of chemically different synthetic ASR gel were also determined. All of these, collectively, served as critical inputs to the mixing model. The resulting developed dielectric mixing model has the potential to be further utilized to quantify the amount of produced ASR gel in cement-based materials. This methodology, once becomes more mature, will bring new insight to the ASR reaction, allowing for advancements in design, detection and mitigation of ASR, and eventually has the potential to become a method-of-choice for in-situ infrastructure health-monitoring of existing structures --Abstract, page v

Rehabilitation of concrete structure using composite materials

In the United Arab Emirates, most of the concrete structures including road, infrastructure and different types of buildings have been reported to be in need of rehabilitation. It is universally acknowledged that the environment of the countries in the Arabian Gulf is extremely severe and very aggressive to construction materials and operations. It is anticipated that the cost of rehabilitation of civil infrastructure will gradually increase over the next decade as a direct consequence of the increase in the number of structures reaching their expected service life. Accordingly demand on rehabilitation methods will increase. In addition the severe climatic conditions of the country will require additional features for this method such as excellent exposure to high temperature fluctuation, moisture and UV contents. The main reasons of reinforced concrete structure\u27s deterioration are corrosion of the steel bars (because of high temperature and humidity of the UAE environment) or continual upgrading of service loads (increase of the traffic load on bridges for example). The solution to these problems is to either re-build the structure or repair the concrete. One of the promising solutions to this problem is to use fiber reinforced concrete (FRC) as replacement for the old methods of repair. The advantages of FRP are lightweight, high tensile strength, corrosion resistance, flexibility and electromagnetic resistance. The object cue of this thesis to, investigate the use of FRP as a strengthening method of concrete structures and its long-term performance, especially in the severe climatic conditions prevailing in the Arab Gulf region

Ceramic technology. How to characterise ceramic glazes

Glazes add value to ceramic, improve its appearance (colour and shine) and make it waterproof. Through the choice of colours and designs, glazes made ceramics fashionable, even luxurious, and therefore, an object of trade. Each region and ruling dynasty developed its own style or trademark which makes them particularly suitable for dating purposes. Therefore, the study and analysis of glazes offers direct information about the acquisition of technical skills (technology), trade of specific materials (interregional links), migrations and the introduction/adoption of new trends. A ceramic glaze is a thin glassy layer fused to the surface of a ceramic body through firing. The interaction between the glaze and the ceramic body results in the interdiffusion of elements between both. A glaze consists mainly of an amorphous phase, but also includes bubbles, cracks and crystalline phases (undissolved compounds and crystals formed during the firing). Finally, the glazes were also decorated, and a large variety of materials and methods of applying the decorations were used. In this chapter, we present a summary of the technical characteristics of glazes (composition, microstructures and technical requirements), their discovery and use throughout history and decorative techniques. The methodology and analytical techniques to obtain the information are also discussed.Peer ReviewedPostprint (author's final draft

Sustainability of Concrete With Synthetic and Recycled Aggregates

Concrete is a material used widely in building and construction applications worldwide; hence, it plays a significant role in the global construction sector. Cement is a major component of concrete and is used in construction applications, either on its own or as a composite with other materials, to improve workability, durability, strength, weight, and shrinkage. However, cement and concrete production and use have adverse environmental effects. Thus, great efforts have been made to produce eco-friendly concrete. This book examines several aspects of sustainable concrete technologies, including new forms of concrete as well as different approaches for creating sustainable cement