Porosity from density measurements

Question 1

What is formula for open porosity?

Answer 1

Po = vol of H2O in open pores / (vol of H2O in open pores) + (vol of solid including closed pores)

Question 2

What’s the equation for weight of water in open pores?

Answer 2

~ (1/p(H2O))*(Ws-Wa)

~ Ws: weight of object + water in open pores

Question 3

What’s the equation for volume of solid including closed pores?

Answer 3

~ (1/p(H2O))*(Wa-Wi)

~ Wi: weight of object - weight of water of volume of object and closed pores

Question 4

What’s the formula for total porosity?

Answer 4

~ Pt = (Vo-Vc)/Vt = 1 - (Wa/Vt)/p

~ p : theoretical density
~ Vo: vol of open pores
~ Vc: vol of closed pores
~ Vt: vol of solid and all pores

Question 5

What’s the formula for Vt; vol of solid and all pores?

Answer 5

~ Vt = Vm + Vo + Vc = (Ws - Wi) / p(H2O)

Question 6

What is the formula for closed porosity?

Answer 6

~ Pc = Pt - Po

Question 7

Where is theoretical density taken from for a pure phase? What about for a multiphase?

Answer 7

~ for a pure phase: the x-ray crystollographic density

~ for a multiphase: the solid is crushed into a fine powder to expose all porosity (no closed porosity), then use PYCNOMETRY