Maybe you could specify what you want to know? Do you want to estimate the absorption rate or the final uptake capacity?

Regarding the uptake capacity it depends on 1) how you do the sorption process and 2) the geometry of the pore space.

1) Sorption: If it is a hydrophilic material and sorption happens via spontaneous imbibition generally air is trapped in the systems. This can be 30 -40% of the whole pore space. Even well connected parts of the pore space will contain air.

2) Factors that prevent complete filling of the pore space (follows from 1) are related the geometry of the pore space. Isolated voids will anyway not be filled. Dead-end pores will also be responsible for air trapping.

Of course, if you keep your samples very long under water and/or do it under vacuum you will finally fill the complete space.

Hi Huinink,

Thanks for your answer.

Actually I am doing an experiment on perlite. I pour perlite into water and shake

for some time then I strain out the water from the mixture. I would like to estimate the amount of water perlite can hold in it. If I know the porosity of the perlite particles, is it possible to estimate the water sorption?

you can measure water vapor isotherm of your materials using IGA , or you can simulate the isotherm if you know the crystal structure of your material. you cannot calculate directly from the pore volume since the total adsorption capacity = excess adsorption capacity + capacity calculated from pore volume

Water penetrates from solis because there are interconnected channels (pores) inside the solid which facilitate its transportation.A stone absorbs moisture from the environment in the vapor form when exposed to rain/rising damp / water vapor condensation.

In the liquid form, it rises up due to capiliary action/ diffusion/ osmosis.In the vapor form, it rises by[1] diffusion as vapors- from pores with high vapor content to pores with lower vapor.[11] hygroscopic action of dissolved hygroscopic salts [111] condensation.

Experiment to calculate water absorbed and % porocity:

Wash the sample with deionized water.Dry for 24hrs at 60C.Place in a descicator over dry silica gel to cool off and wiegh.Repeat the drying process for another 24 hrs; cool and wiegh again to a constant weight (the difference between the two wieghings should not be more than 0.1% of the mass of the sample). Let this constant weight be [Mc].Now place it in a container on a base of glass rods and slowly cover with deionized water untill the sample is totally immersed with about 2cm of water above it.Take the sample out of the container after 8 hrs. Blot it with damp cloth to remove surface water and weigh it. Repeat and weigh again so that the difference in two weights is less than 1% of the water absorbed in 24hrs. Let the constantweight be [Ms].Put the sample in a graduated cylinder filled with deionized water and note the increase in volume indicated by the cylinder. Let this volume be [VApp]; App. stands for apparent.

NowVPore=Ms-Mc.

% open porocity= 100.VPore/Vapp.

the size of pore and their capillarity would play key role in defining the relationship. 

It depends on the material and how much it prefers to imbibe water rather than the other fluids. if your material is water-wet, lower porosity leads to higher inhibition and vice versa.

Side matter, im studying hempcrete. If hempcrete absorbs carbon dioxide from the air does that mean it is porous.