Improvement in Water Resistance of Polymer-Modified Gypsum-Based Composites

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Title: Improvement in Water Resistance of Polymer-Modified Gypsum-Based Composites

Author(s): Y. Ohama, K. Demura, S. Kumagai, M. Joo, T. Katsuhata, D. Sugawara, and D. W. Fowler

Publication: Special Publication

Volume: 193

Issue:

Appears on pages(s): 659-672

Keywords: blast-furnace slag; cement (ordinary Portland); curing; gypsum; silica fume; strength (compressive); strength (flexural)

Date: 8/1/2000

Abstract:
Gypsum is widely used for the manufacture of various building materials because of its advantages such as rapid setting, good thermal insulating property and fire resistance, but their use is limited to interior finishings because of its poor water resistance. This paper deals with an improvement in the water resistance of gypsum composite by the polymer modification and partial replacement of sum with ground granulated blast-furnace slag (Blaine fineness=1 0,000 cm /g , silica fume and ordinary portland cement. Polymer-modified gypsum-based composites are prepared with various polymer-binder (a mixture of gypsum and mineral admixtures) ratios, and tested for water absorption, flexural and compressive strengths before and after water immersion. The water resistance of the gypsum composite is markedly improved by the polymer modification and partial replacement of gypsum with ground granulated blast-furnace slag, silica fume and ordinary portland cement. In addition, the effects of curing conditions on the strength properties of the polymer-modified gypsum-based composites are investigated. As a result, an SBK-modified gypsum-based composite with an optimum mix proportion is proposed from the viewpoints of water resistance, strength development and hair crack disappearance.