Concrete Structures: New Trends and Old Pathologies

Application of hazardous waste management model for cities look into planning a model for collection, storage and disposal of potentially hazardous waste for sustainable cities. The model particularly, illustrates an innovative design for industrial hazardous waste management in a petroleum corporation at Mumbai, India. It is significant that cities shall handle the hazardous waste effectively for sustainable environment conservation. Hazardous waste is potential danger for the citizens in event of disaster. So, what can be effective way to plan a hazardous waste management in cities? How we can develop an accurate model? Some of these research questions are discussed in this research. Finally, this research looks into the major methods for designing a model storage unit for industrial hazardous waste.

In Brazil, buildings use ceramic bricks and Portland cement mortar as constituent materials of the walls, which act as coatings and delimiting elements for internal areas. These materials are porous and highly susceptible to degradation due to the presence of moisture. Water penetrates structures through pores and compromises the useful life of buildings if not identified and treated early. The region between two layers of a wall is called the interface, and due to the presence of this region, the transport of moisture in multilayer elements diverges from those found in monolithic elements. The change in moisture transport behaviour is proportional to the change in the nature of the contact and the water properties of the interface, and it is called as interface resistance. This work sought to obtain information on the storage and transfer of moisture, throughout the useful life of the system formed by ceramic brick and Portland cement mortar. For this, the analysis of the performance of standardized samples was carried out, with different interface configurations, mortar traces, and base dimensions. Different performances were observed for samples of different traits, where some absorbed less water than others. When comparing the different areas of the specimen bases for each trace, in all cases the absorption (moisture content) of water increases as the area is increased. This work presents and discusses the current situation, original techniques, and strategies used in the development of structural reinforcement design of both towers of the Basilica of Penha Church. Repair techniques were, poorly, designed, and conducted in 1981, along with a lack of preventive maintenance, leaks and even the growth of bushes embedded in the masonry led to the instability of the towers of the Basilica of Penha Church. This paper, which combines integrated solutions in a historic monument reinforcement project, was initially challenging and became an important case study, possibly one of the first works using carbon fiber reinforcement in masonry. Another important contribution is the insertion of visitable galvanic protection that enables monitoring and possible replacement of sacrificial anodic inserts, keeping the protection active over time.

Electrical resistivity (ER) becomes an essential tool for decision- making by managers responsible for plans and strategies for concrete structures maintenance. ER is a non-destructive technique for evaluating reinforced concrete structures, mainly regarding reinforcement corrosion risk due to its easy operation, reliability, and quick and low-cost results. Although ER is a widely used technique, little clear information is discussed in the literature regarding the concrete role as an electrical circuit component. Thus, this chapter presents concepts about circuit types applied to understand electrical resistivity and a comprehensive analysis regarding the concrete role in different electrical circuit types. The main parameters that most influence concrete resistivity are discussed.

Self-compacting concrete (SCC) has considerably lower yield stress as compared to the conventional vibrated concrete (CVC) in their fresh condition and this forms one of their primary differences. To place CVC and SCC via pumping, the latter would require a lower pumping pressure to pump and place as it requires lower yield stress in comparison. Pumping is one of the most preferred methods of conveying and placing concrete due to the field requirements of reaching heights and less accessible places. It is obvious that the intensity of pumping pressure might affect the state of fresh properties of concrete, while being pumped and/or placed. Currently, Rheometers are available to measure the fresh properties of pumped concrete under dynamic condition, i.e., while the mixes are being agitated and pumped; similar instruments are not extensively available or used after pumping and placing concrete i.e., when concrete is at rest when supported on a formwork post pumping and placing. It is necessary to study the fresh properties of placement of concrete at rest i.e., under static condition to understand the actual phenomenon under said condition. The current experimental study attempts to determine the fresh properties of concrete under rest i.e., static condition using shear box test. The concrete mixes were proportioned using volume fraction technique and their characteristics were evaluated using both empirical and material science approach.

The results show the uniqueness of the approach for determining the rheological properties of CVC and SCC mixes under static conditions. The study exhibits an interesting finding, which is the invalidation of the use of Bingham model for SCC with a flow value of 800 mm and beyond.

The use of civil construction waste has been consolidated as a way to achieve sustainability in civil construction, as well as reduce the environmental impacts resulting from the improper disposal of this material. Due to the specificities of its products, civil construction has a large field where this waste can be used as raw material. The objective of this work is to contribute to studies on the possibilities of using sewage sludge as a way to improve the characteristics of the soil in collapse and as small concrete aggregates. Sewage sludge with 25, 50 and 75 mg/ha from the Mangueira and Curado treatment stations was used with an addition of about 5%, 10%, and 15%. In order to characterize the properties of sewage sludge and analyze its interaction with the soil and concrete specimens, several tests were carried out, such as: physical and chemical tests, scanning electron microscopy tests, hydraulic conductivity tests, chemical mobility tests, compressive strength tests, sclerometric tests, and ultrasonic pulse velocity tests. The results obtained allowed us to conclude that the addition of sewage sludge to the soil contributed to reduce its collapsibility, showing that this procedure can be useful for improve the performance of collapsible soils. It was also observed that when the proportion of sewage sludge was increased in substitution for small-size concrete aggregates, the compressive strength and water absorption decreased when compared to a concrete block made with usual aggregates. The behavior obtained indicates that the use of sewage sludge to replace the small-sized concrete aggregate part should be used with caution, even in small-sized buildings, requiring advanced studies to explore its use as a material building.