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- Alkali-activated (1)
- Ammonium Polyphosphate (1)
- Biosomposites (1)
- Cone Calorimeter (1)
- Corrosion (1)
- Deformation-induced martensite (1)
- Electrochemical investigations (1)
- Expandable Graphite (1)
- Fire retardancy (1)
- Flame retardancy (1)
The development of alkali‐activated materials (AAMs) as an alternative to Portland cement (PC) has seen significant progress in the past decades. However, there still remains significant uncertainty regarding their long term performance when used in steel‐reinforced structures. The durability of AAMs in such applications depends strongly on the corrosion behaviour of the embedded steel reinforcement, and the experimental data in the literature are limited and in some cases inconsistent. This letter elucidates the role of the chemistry of AAMs on the mechanisms governing passivation and chloride‐induced corrosion of the steel reinforcement, to bring a better understanding of the durability of AAM structures exposed to chloride. The corrosion of the steel reinforcement in AAMs differs significantly from observations in PC; the onset of pitting (or the chloride ‘threshold’ value) depends strongly on the alkalinity, and the redox environment, of these binders. Classifications or standards used to assess the severity of steel corrosion in PC appear not to be directly applicable to AAMs due to important differences in pore solution chemistry and phase assemblage.
A comprehensive characterization of the thermal and the fire behaviour is presented for polypropylene (PP) flax compounds containing ammonium polyphosphate (APP) and expandable graphite as fire retardants. Thermogravimetry coupled with an evolved gas analysis (TG-FTIR) was performed to ensure a significant thermal analysis. The fire response under forced flaming conditions was studied using a cone calorimeter. The external heat flux was varied between 30 and 70 kW m-2 so that the results could be evaluated for different fire scenarios and tests. Different flammability tests (UL 94, limiting oxygen index, glow wire test, GMI 60261) were performed and the results compared with the cone calorimeter data. The different char forming mechanisms are described and the resulting fire retardancy is classified. The successful and ecological friendly fire retardancy is a technological breakthrough for PP/flax biocomposites.
Contents of deformation-induced martensite in the lattice structure of austenitic stainless steels lead to an either beneficial or detrimental change of mechanical and magnetic properties depending on the prospective application. Whereas these changes are well-known and investigated widely the influence of deformation-induced martensite on the corrosion behaviour is frequently an issue of scientific discussions. There are opposing opinions that depend on the type of corrosion mechanism being investigated for example regarding pitting corrosion resistance in Chloride containing media. In it is stated that pitting resistance is not influenced by deformationinduced martensite while in it is discussed that more pitting occurs on martensitic structure. The same conflictive opinions appear regarding active dissolution in acidic media or intergranular corrosion. In addition, when having deeper insight into literature it can be concluded that even the type of test method, i. e. dynamic or static testing, has a big influence on the obtained results concerning the influence of martensite in austenitic stainless steels.