The method to calculate the gel porosity ϕgw depends on the model used to represent the C-S-H phase. An overview of the calculation methods are given in the table below.


Database

C-S-H model

Calculation Method

CEMDATA

CSHQ model

If the C-S-H is represented by the CSHQ model (Kulik, 2011), the volume of the C-S-H based on its end members includes both the volume of the solid phase and the volume of the gel porosity. The gel porosity is calculated based on the Ca/Si (CS) ratio of the C-S-H :


with a1, a2, a3, a4, and a5 equal to, respectively, -3.67474, 14.75335, -19.00002, 10.931594, and -2.266734. The mass of gel pore water, mgw [g], is obtained by:

where nSi is the number of moles of Si in the C-S-H, and MH2O is the molar mass of H2O. The volume is obtained by assuming a density of 1 kg/dm³.

Otherwise

ϕgw = 0