Investigations of nanostructured three-phase-foams and their application in foam concretes – A summary
Advanced Materials Letters,
2017, Volume 8, Issue 11, Pages 1072-1079
AbstractRecently, 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.
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