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2011-Sustainable Industrial Processing Summit
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Editors: | Florian K |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2012 |
Pages: | 646 pages |
ISBN: | 978-0-9879917-6-8 |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
It is a general perception that cement-based materials as concrete and reinforced concrete are relatively simple and as such are considered "low-tech" materials, or at least are ranked as far less complex if compared to bio-engineered materials or fuel cells for example. However, concrete has never been a "simple" material. The development of the required mechanical properties and further the necessary engineering performance starts on the nano/micro level of a hydrating cement matrix. Concrete is the material with highest level of consumption (second after water) and is essential in each aspect of our life. Concrete is a durable material, however, it surely has weaknesses and a more or less determined service life, since environmental factors affect to a large extent the life cycle of our structures. Further, when it comes to reinforced concrete, both materials, i.e. steel and concrete, have to be considered and their material performance taken into account within service life. To this end, corrosion of steel in reinforced concrete is a major concern, since it affects the global performance of a structure and can have detrimental influence in short terms. In order to control (minimize or stop) the corrosion related issues, various methods, techniques and applications are well known and available. Novel solutions and smart materials are, however, currently demanded by the engineering practice. Damage initiation (e.g. due to corrosion) or the development of the cement-based matrix, start on nano/micro level. Therefore, the purpose of our study is to influence the material properties (both steel and concrete) on the nano/micro level and thus to control eventual deterioration mechanisms (as corrosion) or achieve superior properties of the cement-based matrix (e.g. uniform distribution of hydration products, reduced permeability etc.). Nano-aggregates (PEO-b-PS micelles) and/or hybrid composite aggregates (CaO particles, covered with a multi-layer of poly-electrolytes PDADMAC/PAA) were admixed in mortar and reinforced mortar in very low concentrations (0.006 wt.% per mortar weight). Some of the main results refer to achieved superior properties of the bulk matrix: significantly reduced porosity (at least 2 times) and water permeability (3 orders of magnitude) in the presence of micelles. Further, the presence of hybrid aggregates increases the corrosion resistance of steel, compared to the control, micelles and hybrid aggregates-free mixtures. The paper will further discuss the mechanisms, related to the influence of these "complex" formations on cement hydration mechanisms and the phenomena within their performance at the steel/cement paste interface, resulting in increased corrosion resistance of modified reinforced mortar.