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The effects of chlorides on the corrosion of steel bars within a matrix comprising modified magnesium oxysulfide (MMOS) cementitious materials was investigated. The phase composition, morphology and distribution of steel corrosion products (SCPs) were studied. There was basically no corrosion of the steel bars in the MMOS cement without chlorides. A high chloride content and a high water/cement (w/c) ratio in the MMOS matrix had adverse effects on the steel bar corrosion. The primary SCPs in the MMOS mixes were iron oxyhydroxides (FeOOH) and ferric oxide (Fe2O3), while ferrous oxide (FeO) was only observed at low w/c ratios, indicating a lower degree of oxidation. The presence of di-iron nonacarbonyl (Fe2(CO)9) at high w/c ratios suggested a higher degree of oxidation. At lower w/c ratios, rust products readily diffused. Conversely, at higher w/c ratios, these products accumulated close to the steel bars, resulting in a compact structure. [ABSTRACT FROM AUTHOR]

Transforming the building sector toward sustainability based on green building (GB) technologies is a multi-faceted, multi-actor process of socio-technical transition. Understanding the different roles of primary actors in both technological and non-technological dimensions of GB transition is pivotal for effectively engaging multiple GB stakeholders during this process. However, relevant research is rare in the GB literature. This paper conducts an actor analysis based on a conceptual framework constructed on the actor and power relation typology from the multi-actor perspective approach and regime insights from the multi-level perspective theory. A qualitative case study of Singapore is adopted to exemplify the roles of the government, developers, citizens and NGOs, determined by their respective power and multi-actor power relations, and to evaluate their synergetic influence on the technological, social and governance dimensions of the GB transition. It was found that the government leads all three dimensions of GB transition and it has an indirect impact on promoting the technological transformation and social adaption by synergizing the other three actors. As the intermediary between government and non-government actors, NGOs indirectly influence GB transition by primarily assisting the government. Developers and citizens directly contribute to technological transformation and social adaption, respectively, and they have an indirect impact on the opposite dimensions through interacting with one another. We argue that a successful GB transition entails synergies from multi-actor interactions and the interplay of technical and non-technical development. This paper offers a heuristic framework for multi-actor analysis in the multi-faceted GB transition and generates policy lessons for other cities. [ABSTRACT FROM AUTHOR]