Why the foam concrete with cement stability requirements?

Why the foam concrete with cement stability requirements?
Cement stability refers to the volume change whether is even after hardened cement, cement stability is unqualified, foam concrete cracks, the project was dangerous, so the production of foam concrete cement to pass test, stability good to use.Otherwise, will bring great bad effect!
In addition of cement storage time not too long, the cement particles of air and water vapour, carbon dioxide (hydration reaction) reduce the cementing ability.Be affected with damp be affected with damp serious when, all formed lumps, cannot use.Cement strength decreased significantly after be affected with damp be affected with damp, setting time will also be extended.This can affect the final effect of foam concrete, please careful choice!