Jay Sanjayan

Bio: Jay Sanjayan is an academic researcher from Swinburne University of Technology. The author has contributed to research in topics: Geopolymer & Compressive strength. The author has an hindex of 64, co-authored 387 publications receiving 15051 citations. Previous affiliations of Jay Sanjayan include Monash University, Clayton campus & RMIT University.

Green house gas emissions due to concrete manufacture

Abstract: The issues of environmental impacts of concrete have become important since many major infrastructure owners are now requiring environmentally sustainable design (ESD). The carbon dioxide (CO2) emissions are often used as a rating tool to compare the environmental impact of different construction materials in ESD. Currently, the designers are forced to make estimates of CO2 emissions for concrete in ESD based on conjecture rather than data. The aim of this study was to provide hard data collected from a number of quarries and concrete manufacturing plants so that accurate estimates can be made for concretes in ESD. This paper presents the results of a research project aimed to quantify the CO2 emissions associated with the manufacture and placement of concrete. The life cycle inventory data was collected from two coarse aggregates quarries, one fine aggregates quarry, six concrete batching plants and several other sources. The results are presented in terms of equivalent CO2 emissions. The potential of fly ash and ground granulated blast furnace slag (GGBFS) to reduce the emissions due to concrete was investigated. A case study of a building is also presented. Portland cement was found to be the primary source of CO2 emissions generated by typical commercially produced concrete mixes, being responsible for 74% to 81% of total CO2 emissions. The next major source of CO2 emissions in concrete was found to be coarse aggregates, being responsible for 13% to 20% of total CO2 emissions. The majority contribution of CO2 emissions in coarse aggregates production was found to from electricity, typically about 80%. Blasting, excavation, hauling and transport comprise less than 25%. While the explosives had very high emission factors per unit mass, they contribute very small amounts (<0.25%) to coarse aggregate production, since only small quantities are used. Production of a tonne of fine aggregates was found to generate 30% to 40% of the emissions generated by the production of a tonne of coarse aggregates. Fine aggregates generate less equivalent CO2 since they are only graded, not crushed. Diesel and electricity were found to contribute almost equally to the CO2 emissions due to fine aggregates production. Emission contributions due to admixtures were found to be negligible. Concrete batching, transport and placement activities were all found to contribute very small amounts of CO2 to total concrete emissions. The CO2 emissions generated by typical normal strength concrete mixes using Portland cement as the only binder were found to range between 0.29 and 0.32 t CO2-e/m3. GGBFS was found to be capable of reducing concrete CO2 emissions by 22% in typical concrete mixes. Fly ash was found to be capable of reducing concrete CO2 emissions by 13% to 15% in typical concrete mixes. The results presented are based on typical concrete manufacturing and placement methods in Australia. The data presented in this paper can be utilized to compare green house gas emissions due to concrete with those associated with alternative construction materials. The various rating schemes used to compare alternative construction materials should use models such as the one presented in this paper, based on hard data so that reliable comparisons can be made. A case study is presented in this paper demonstrating how the results may be utilized.

Additive manufacturing (3D printing): A review of materials, methods, applications and challenges

Abstract: Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.

Climate change 2014 - Mitigation of climate change

Abstract: The talk with present the key results of the IPCC Working Group III 5th assessment report. Concluding four years of intense scientific collaboration by hundreds of authors from around the world, the report responds to the request of the world's governments for a comprehensive, objective and policy neutral assessment of the current scientific knowledge on mitigating climate change. The report has been extensively reviewed by experts and governments to ensure quality and comprehensiveness.

Polymers for 3D Printing and Customized Additive Manufacturing

Abstract: Additive manufacturing (AM) alias 3D printing translates computer-aided design (CAD) virtual 3D models into physical objects. By digital slicing of CAD, 3D scan, or tomography data, AM builds objects layer by layer without the need for molds or machining. AM enables decentralized fabrication of customized objects on demand by exploiting digital information storage and retrieval via the Internet. The ongoing transition from rapid prototyping to rapid manufacturing prompts new challenges for mechanical engineers and materials scientists alike. Because polymers are by far the most utilized class of materials for AM, this Review focuses on polymer processing and the development of polymers and advanced polymer systems specifically for AM. AM techniques covered include vat photopolymerization (stereolithography), powder bed fusion (SLS), material and binder jetting (inkjet and aerosol 3D printing), sheet lamination (LOM), extrusion (FDM, 3D dispensing, 3D fiber deposition, and 3D plotting), and 3D bioprinting....

Properties Of Concrete

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