Search

Natural pozzolans are defined as either raw (volcanic material, limestone) or calcined natural materials (burnt shale, calcined kaolinite) with pozzolanic properties. Historically, they are among the oldest materials that have been used in combination with lime for construction purposes. For example, Santorin earth is a natural pozzolan from a volcanic eruption around 1500 BCE on an island of the same name in Greece. Over the last decades, research into cement matrices has been changing direction, owing to deeper environmental concerns over the impact of the cement industry and its consequences for climate change. Global environmental policies are increasingly strict, prioritizing the re-use rather than the disposal of industrial wastes. In this context, one of the biggest challenges is the search for strategies that promote the industrial rotation of high volumes of wastes in their productive cycles. The main purpose of this research is to widen the existing knowledge base on the behavior of new mineral pozzolans of high added value in the cement sector, lending special attention to paper sludge wastes generated in the process of paper manufacture, in which recycled paper is used as a raw material. The results to date show that, once thermally activated (in the range of 650–700°C), paper sludge turns out to be an alternative source of recycled metakaolin. This product is characterized by its high pozzolanic activity and improved performance with regard to the benefits of certain binary cements. The possibility of incorporating this industrial waste in cements along with other already standard pozzolans focuses, as mentioned, on the notable increase in the production of these types of cements. This is due, at present, to the extensive constructive applications for type-II cements (single additive) and to their lower economic and energetic costs that also makes them more suitable in times of economic crisis. In the present paper, the influence that pozzolan blends (activated paper sludge and fly ash) have on the reaction kinetics of ternary blended cements (6 and 21% of replacement) is evaluated, paying special attention to the identification and evolution of hydrated phases with increasing reaction times. The results obtained represent a pioneering research line at a global level and represent a starting point for future investigations because in the case of using paper sludge, release of CO2 from organic matter is very low and is listed as zero release

This paper introduces the study on treatment on the secondary biochemical effluent of pulp and paper wastewater by ozonation, and investigates the effects of the ozonation process on the wastewater COD, chroma, UV 254 and turbidity removal efficiency during ozone dosage, contact time and so on. The results showed that ozonation treatment effect was good, and with the increase of ozone dosage and contact time, the wastewater COD, chroma and UV 254 experimental conditions removal rate was increasing, and the optimum were that the ozone dosage was 126.46~147.37mg/L and contact time was 1.30~1.74h. Ozonation has a certain removal efficiency for turbidity, and turbidity removal rate was in a large range of 1.88~77.51%, but there is no obvious correlation with the ozone dosage and contact time.

Over the last few years, students taking the Introduction to Geotechnical Engineering course at Tufts University have performed term projects where they develop written reports and oral presentations on various topics in geo-engineering. This paper presents how these efforts have enhanced the learning experience of the course. Specifically, the paper presents how the project is integrated into the course, assessment methods used for grading, and the value such projects have had on student learning, based on post-course evaluations. A shortened example of a student’s work is presented. It can be concluded that the project allows not only a deeper appreciation of geo-engineering by the students, but also provides an avenue for students to practice their communication skills; one of the ABET Criterion 3 outcomes.

A complex cleanup project that included dredging and capping of contaminated sediment, construction of two breakwaters, habitat enhancement, upgrade of a seasonal small craft facility and installation of new aids to navigation was completed by the Port of Anacortes, Washington in collaboration with the Department of Ecology, Washington and potentially responsible parties (PRP). The complexity of project site physical processes, extent of dredging, and strict regulatory requirements on the clean-up action necessitated an innovative engineering approach to all above elements of the project. The approach also included application of the most advanced coastal engineering modeling tools including wave, tidal flow, sediment transport and stability, and coastal geomorphology hydrodynamic simulators. Based on analysis of the numerical modeling results, optimal engineering decisions were made for design and construction of detached breakwaters, dredging and removing a portion of the contaminated sediment, capping of the remaining contaminated sediment, and removing the old deteriorating creosoted sheetpile wall breakwater. Also, the results of the study determined the possibility of creating a sheltered eelgrass habitat and year-round small craft facility for different types of activities such as fishing, kayaking, and sailing.