Chloride binding of alkali-activated slag/fly ash cements

Study on chloride binding capability of coal gangue based cementitious materials

Utilization of pretreated fly ash to enhance the chloride binding capacity of cement-based material

https://northumbria-test.eprints-hosting.org/id/document/273565

Mechanical and durability performance of marine sand and seawater concrete incorporating silicomanganese slag as coarse aggregate

Slag hydration and chloride binding in slag cements exposed to a combined chloride-sulphate solution

The corrosion of steel caused by chloride ions is considered to be the main durability problem of reinforced concrete structures. This paper investigates the total chloride ion content, free chloride concentration in expressed pore solution, Friedel’s salt content, and porosity of portland cement (PC) and PC/fly ash (FA) combination pastes after 7 days of water curing followed by 28 or 150 days immersion in water or 0.3, 0.7, 1.0, and 2.0  mol/L sodium chloride solutions. Results showed that the chloride ion binding capacities of the pastes increased with increase of free chloride ion concentration. The relationship between bound and free chloride ion contents could be described by Langmuir’s equation. The addition of fly ash decreased the bound chloride content and showed negative influences on Friedel’s salt formation due to low activity. Porosity of cement paste decreased as the concentration of soaking chloride ion increased, and was inversely proportional to the amount of Friedel’s salt formed.

Effects of Chloride Ion Binding on Microstructure of Cement Pastes

Significance About 90% of all mechanical service failures are caused by fatigue. Avoiding fatigue failure requires addressing the wide knowledge gap regarding the micromechanical processes governing damage under cyclic loading, which may be fundamentally different from that under static loading. This is particularly true for deformation-induced martensitic transformation (DIMT), one of the most common strengthening mechanisms for alloys. Here, we identify two antagonistic mechanisms mediated by martensitic transformation during the fatigue process through in situ observations and demonstrate the dual role of DIMT in fatigue crack growth and its strong crack-size dependence. Our findings open up avenues for designing fatigue-resistant alloys through optimal use of DIMT. They also enable the development of physically based lifetime prediction models with higher fidelity.

The dual role of martensitic transformation in fatigue crack growth

Quantitative thermographic methodology (QTM), which takes energy dissipation as a fatigue indicator, has been successfully applied to predict the fatigue life of materials and welded joints under constant amplitude loading. This study advances the QTM approach for predicting the fatigue life under variable amplitude loading in both low and high cycle fatigue regimes. Experimental data, obtained by fatigue tests under variable amplitude loading, were used in order to apply the developed QTM approach and to demonstrate that it is able to take into account the loading sequence effect. Good predictions of the fatigue life were achieved.

Quantitative thermographic method for fatigue life prediction under variable amplitude loading

This paper focuses on a comparative study of the critical plane approach (CPA) and the dissipated energy approach (DEA) for multiaxial fatigue evaluation on an AISI 316L steel. It is a follow-up to our previous study on the development of a DEA model for multiaxial fatigue life prediction. The results demonstrate that the developed DEA model can provide overall better performance compared with some classic CPA models both in terms of prediction accuracy and versatility to multiaxial loading paths. An in-depth crack mechanism investigation reveals that the multiaxial fatigue life is mostly spent in the formation of micro-cracks, which exhibits distinct characteristics under the different loading paths examined. This effect can be better considered by using DEA model compared with the CPA models adopted. 

Xiaogang Wang

Papers

Effects of Chloride Ion Binding on Microstructure of Cement Pastes

The dual role of martensitic transformation in fatigue crack growth

Quantitative thermographic method for fatigue life prediction under variable amplitude loading

Multiaxial fatigue evaluation of type 316L stainless steel based on critical plane and energy dissipation

Effect of Texture Evolution and Defect on the Crack Initiation of a Ni-Based Superalloy Electron Beam Welded Joint