Reaction of Sodium Silicate (water glass) with Zinc Oxide?

I was reading about [different additives](https://adhesives.specialchem.com/tech-library/article/sodium-silicate-adhesives) for Sodium Silicate (water glass) and noticed this line in particular:



> 
> The water-resistance of sodium silicate solution adhesives may also be
> improved by the addition of fine powders such as zinc oxide or
> amorphous calcium carbonate. These additives will react slowly with
> the silicate to form an insoluble mass
> 
> 
> 


I would like to understand what kind of *insoluble mass* is formed by the addition of Zinc Oxide.


What I've found so far points towards "disodium zinc silicate" (Na2(ZnSiO4)), which according to [this paper](https://www.sciencedirect.com/science/article/abs/pii/S0304386X12002599) forms as a precipitate from the combination of Na2SiO3 + ZnO + NaOH. Could this also occur without the NaOH present as implied by the additives website? I don't currently have access to the full paper, so I'm just going off of the info in the abstract.


I also see very little info online about "disodium zinc silicate". Is it electrically or thermally conductive? Is it stable at high temperatures?


Does it really do anything different for the properties of the Sodium Silicate than adding an inert filler?


