Christina Kr
Abstract
Recently, a new approach was developed and published which focuses on the preparation of inorganic foams and their application in foam concrete production. Through the incorporation of nanostructured pozzolans in the foam structure, so-called three-phase-foams show a higher stability than foams only ...
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Recently, a new approach was developed and published which focuses on the preparation of inorganic foams and their application in foam concrete production. Through the incorporation of nanostructured pozzolans in the foam structure, so-called three-phase-foams show a higher stability than foams only based on surfactants. Due to pozzolanic hardening, shrinkage cracks were healed and reaction products can be observed. By implementation of nanotubes in the foam structure as nanoreinforcement, a further stabilization was reached. After incorporation of wet three-phase-foams in cement paste, foam concretes with improved mechanical properties were achieved. It was also shown that the pore size distribution was similar to the introduced three-phase-foams and also smaller pore sizes can be observed compared to foam concretes based on surfactant foams. Additionally, a specific shell-like pore structure was obtained and a theoretical model developed. This could be confirmed by investigations of the influence of the surfactant used on the formation and carbonation of calcium hydroxide. To further enhance the mechanical properties of foam concretes based on three-phase-foams, an UHPC (Ultra-high Performance Concrete) formulation has been applied. Resultant UHPC foam concretes showed dense packed borders, improved homogeneity related to the pore size distribution and enhanced mechanical properties. Furthermore, the UHPC approach was combined with nanoreinforcement.
I. Koirala; B. P. Singh; I. S. Jha
Abstract
We have used simple statistical model to report the energetic and its effect on the alloying behavior of Bi-Sn and Bi-In liquid alloys. The energetic of mixing in liquid alloys has been analyzed through the study of bulk and surface properties. In the bulk, we have studied thermodynamic properties, which ...
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We have used simple statistical model to report the energetic and its effect on the alloying behavior of Bi-Sn and Bi-In liquid alloys. The energetic of mixing in liquid alloys has been analyzed through the study of bulk and surface properties. In the bulk, we have studied thermodynamic properties, which include Gibb’s free energy of mixing, enthalpy of mixing and entropy of mixing. The surface behavior has been analyzed by computing surface concentration and surface tension of the alloys. For the microscopic structural investigation our study includes concentration-concentration fluctuation in long wavelength limit and Warren-Cowley short range order parameter, they have been discussed in term of the energetic of the bulk as well as that of the surface part. The computed results are in good agreement with experimental data and support a weak phase-separation tendency in molten Bi-Sn system and ordering behavior in Bi-In system. In both system, temperature dependent energy parameter takes important role to explain bulk and surface properties.
