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Direct foaming and seeding of highly porous, lightweight gypsum

Published online by Cambridge University Press:  15 July 2016

Elisabet Roch Isern  and
Gary L. Messing
Elisabet Roch Isern*
Affiliation:
Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802
Gary L. Messing
Affiliation:
Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802
*
a) Address all correspondence to this author. e-mail: eroch.isern@gmail.com
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Abstract

This paper describes the direct-foaming of plaster of Paris (CaSO4·½H2O) with up to 1.7 wt% of a nonionic surface-active agent to obtain highly porous, lightweight gypsum (CaSO4·2H2O) with 65–70% total porosity and a homogeneous, bimodal pore size distribution. Based on viscosity and temperature changes in the setting plaster of Paris slurry, the nonionic surfactant is seen to retard gypsum crystallization and thus extend the working time at higher water to solid ratios. The increase in viscosity during gypsum crystallization stabilizes the macropores formed during foaming. Gypsum foams of 32% density with a submicron matrix pore size, and relatively uniform macropore size of ∼100 µm were obtained. Seeding the process with 0.5 wt% 100 µm diameter gypsum particles accelerates gypsum crystallization in the presence of the nonionic surfactant and results in a more uniform, finer (92 µm) macropore structure due to less time for bubble coalescence.

Keywords

insulatorfoamporosity

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Type
Articles
Information
Journal of Materials Research , Volume 31 , Issue 15 , 15 August 2016 , pp. 2244 - 2251
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Copyright
Copyright © Materials Research Society 2016 

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References

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