norew:

how Ca(OH)2 + HCl increases free lime?

Norew,

I'm not sure what you mean.  Ca(OH)2 + HCl doesn't increase free lime.

Ca(OH)2 is produced during the reactions of clinker minerals and/or free lime with water, during cement hydration.  HCl is a titrimetric reagent used in the determination of CaO + Ca(OH)2 in clinker or cement using the Ethylene Glycol/Ethanol extraction method.

Regards,

Ted.