

To elaborate a little, the reason you use specific sand for concrete, and not just any sand is because of viscosity. When you use a sand that is too coarse, the mixture becomes more thick and viscous, which is harder to pour. So you end up adding more water to the recipe to make it pourable which makes it weaker since the ratio of water to cement is thrown off




So they get another page view every time you have to refresh to see the content behind the pop-up.
If they wanted to force logins they’d grey out the text like newspaper websites do.