CHEMICAL AND MICROSTRUCTURAL CHANGES AT ALKALI-RESISTANT GLASS FIBER-CEMENT INTERFACES


YILMAZ V. T. , LACHOWSKI E., GLASSER F.

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, vol.74, no.12, pp.3054-3060, 1991 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 74 Issue: 12
  • Publication Date: 1991
  • Doi Number: 10.1111/j.1151-2916.1991.tb04301.x
  • Title of Journal : JOURNAL OF THE AMERICAN CERAMIC SOCIETY
  • Page Numbers: pp.3054-3060
  • Keywords: CEMENTS, FIBERS, GLASS, REINFORCEMENT, ALKALI RESISTANCE, REINFORCED CEMENT, DURABILITY, SURFACE, ATTACK

Abstract

Portland cement matrices have been reinforced by 5 wt% of "CemFIL 1" alkali-resistant glass fiber and isothermally wet cured for up to 1 yr at 20-degrees and 55-degrees-C. Degradation of mechanical properties occurs as a consequence of chemical attack on the fibers. Various stages of the degradative process are followed by electron microscopy and analysis. The original composite microstructure is described in terms of a solid fiber reinforcing system. However, the fibers gradually become hollow, leaving a concentric shell of cement-fiber reaction product which still gives a useful measure of reinforcement. These changes, together with fiber shortening arising from local impingement of Ca(OH)2 crystals, give rise to what is termed a hollow cylinder reinforcement system. The hollow shell structures consist of gel and semicrystalline material; glass is absent or nearly so. The role of zirconia in stabilizing the hollow cylinder structures is described. It is considered that the microstructure developed at approximately 20-degrees-C, while not as effective a reinforcement as solid fibers, still provides useful tensile reinforcement relative to plain paste matrices.