The interfacial transition zone between filler and matrix in cement based composites with cenospheres
Wakdemar Pichór AGH University of Science and Technology, Faculty of Materials Science and Ceramics Mickiewicza 30, 30-059 Cracow, Poland
Quarterly No. 3, 2006 pages 71-77
DOI:
keywords: interfacial zone, cenosphere, cement composites, lightweight fillers
abstract Cenospheres from coal ash are lightweight filler applied in cement based composites. The interfacial transition zone between cement paste and cenospheres was investigated by SEM observations, X-ray analysis into micro regions and XRD method. In case of cement based composites the interfacial transition zone was found only for naturally hardened cement and the zone had discontinuous character. For autoclaved sample of Portland cement the cement paste in the vicinity of cenosphere’s surface was compact and there were no difference in relation to distant region of cement paste. In case of cenospheres with lime the pozzolanic properties of filler resulted in formation on its surface the hydration products. A needle-like forms of C-S-H phase and tobermorite were found. The interaction between high aluminum cement paste and cenospheres also leads to formation of bulk products of hydration. No interfacial transition zone was observed for sample with high aluminum cement. The paste close to cenosphere’s surface was compact, without microcracks and gaps, that usually indicate good adhesion of hydration products to the surface of filler. Obtained results suggest that the cenospheres are good filler for production of the cement based composites, both naturally hardened and autoclaved.