Determination of Optimum Ingredients for Phosphogypsum Composite Stability under Marine Conditions-Response Surface Analysis with Process Variables
Publication: Journal of Environmental Engineering
Volume 129, Issue 4
Abstract
The construction of mixture designs and the methods of response surface analysis of mixture data are discussed and applied for determining the optimum ingredients for stabilized phosphogypsum (PG) composites conducive to marine application. Of particular importance is the ability of the composites to maintain physical integrity when submerged. Therefore, potential indicators for the survivability of the stabilized PG composites were also screened. The triangular coordinate system was used to present the three ingredient components of the PG composites as well as their dependent variables. The augmented simplex centroid design with pseudocomponents was used in determining mixture ingredient composition. A quadratic model with two process variables was used to analyze the experimental results and predict the optimum ingredient composition. The model predicts that a series of PG: class C fly ash:portland type II cement ingredients, such as 62%:35%:3% PG:class C fly ash:portland type II cement and 65%:31%:4% PG:class C fly ash:portland type II cement composites with class C fly ash content (30.7–36.6%) and portland type II cement content (2.7–4.2%), can survive in marine environments for more than two years. The indicator screening for the survivability of the stabilized PG composites in the marine environment showed that the minimum wet leached surface hardness, minimum wet control surface hardness, and maximum effective diffusion coefficient may serve as indicators.
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Information & Authors
Information
Published In
Journal of Environmental Engineering
Volume 129 • Issue 4 • April 2003
Pages: 358 - 365
Copyright
Copyright © 2003 American Society of Civil Engineers.
History
Received: Dec 14, 2001
Accepted: Jun 21, 2002
Published online: Mar 14, 2003
Published in print: Apr 2003
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