De or het puinfundering?

The correct Dutch article is:

de puinfundering

Rule Words ending in -ing: almost always de. See the rule

How to use puinfundering

the puinfunderingde puinfundering
this puinfunderingdeze puinfundering
that puinfunderingdie puinfundering
our puinfunderingonze puinfundering
your puinfunderingjouw puinfundering
every puinfunderingelke puinfundering
which puinfundering?welke puinfundering?
a big puinfundering / the big puinfunderingeen grote puinfundering, de grote puinfundering