Hi Justin R.
I am researcher in field of Nanotechnology, so I am a eligible person for answering your question.
The photocatalytic activity is tested in air purification after NOx removal. Also the self cleaning properties are tested during dye removal.
TiO2 effects the hydrated Cement: It is a stable , during hydrated process.
TiO2 makes C-S-H bond more compact , which increase the compressive strength.