Potential of Portland cements for MDF materials

Macro-defect-free (MDF) materials comprise a "hot topic" example in the field of cement-based materials and composites. The methods of MAS-NMR and thermal analysis gave key data for monitoring the scope of A1-O-P cross-links both in virgin MDF test pieces and in those exposed to moisture. The increased contents of calcium aluminate hydrates, calcium silicate hydrates and CaCO3 in moisture-attacked (as opposed to virgin) MDF probes have been detected by these methods. The controlling feedback from cross-links and interfaces to the extent of secondary interactions of MDF materials with out-door atmospheric humidity is evident. Data on both the next-nearest-neighbour (NNN) interactions and the thermal stability of cross-linked interfaces show that for MDF materials chemical knowledge is crucial to (i) procedure design; A1-O-P cross-linking is the key nano-scale aspect of the MDF formation process and (ii) exploitation; interfaces comprise compact and stable regions in which A1-O-P cross-links support moisture resistance in the MDF materials. (c) 2007 Elsevier Ltd. All rights reserved.