Stucco Aging

Castle Lemberk Middle age Stucco decoration Collagens... 

The stuccos prepared in the laboratory were aged at ZTC and 65% relative humidity for various periods of time. Two stucco properties, that is, consistency and disintegration, were determined immediately after calcining and after various periods of aging. These tests were continued until equilibrium values had been reached the times required to reach these values are given in Table 1. The consistency test methods and the techniques to obtain particle size data, as well as the treatment of these data, are described briefly below. 

Figures 3 through 6 illustrate the effect of aging time on consistency and disintegration, as well as the relationship between consistency and disintegration for continuously calcined Terra Alba. These data show that both consistency and disintegration decrease with time and suggest a linear relationship exists between these properties. Regression analysis of the data yields slopes, intercepts, and correlation coefficients of these curves a.s given in Table 2. Similar data for batch calcined stucco are summarized in Table 3.

In considering other factors that may influence water demand, many intrinsic stucco properties must be taken into account such as purity, particle size and morphology of the gypsum, calcination methods, and stucco surface properties. In addition, the water demand of stucco is dependent on its history such as aging time and conditions, aridization, and presence of surface active agents. 

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