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You must provide STADIUM® with initial values for each variable in the model. You must also provide data on the initial composition of the hydrated cement paste. The window (see Figures 27) is divided into three main sections: moisture and temperature, concentration, and solid phases. If the user selected a material from the database without modifying its characteristics, he does not need to access the Initial Values menu.
Figure 27 – Material Properties window - Initial Values tab
In the Moisture and Temperature section, the user must provide the initial degree of the material saturation. Degree of saturation is defined as volumetric water content divided by porosity. The default value for this parameter is 100%, which means that water content is initially equal to porosity. In high performance materials, self-dessication can decrease this parameter. In that case, the user can make the appropriate adjustment to the degree of saturation. In this section, the user must also provide the initial temperature of the material at the beginning of the simulation.
In the Concentration section, the user must provide STADIUM® with the initial composition of the pore solution, in mmol/L. This experimental parameter may be obtained from the pore solution extraction procedure. This test is fully explained in the Experimental procedure section at the end of this document. The user must ensure that the solution is neutral, i.e. positive charges equal negative charges. If electro-neutrality is not respected, STADIUM® warns the user before the simulation starts. The solution may then be adjusted by modifying the sodium (Na+) content.
In the case of sequential scenarios (base scenario and repairs scenarios), Stadium ® automatically checks on Get Initial conditions from external file and link the corresponding initial values filename: previous scenario filename with extension “.ICF”.
Finally, enter the initial content of the solid phases that form the hydrated cement paste of the material (in g per kg of material). Usually, the paste is considered as initially composed of Portlandite (CH), C-S-H and monosulfate (Afm). These parameters can be estimated from the cement’s chemical composition and mixture characteristics. An embedded component in the Input Data –Material Properties Window is provided with the Software to assist in this calculation
If you select a material from the Database, the solid phases are computed and filled automatically. So the user is not invited to compute again these values.
Figure 28 – Material Properties window - Initial Values tab: Background Chloride content in aggregates
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