De or het asfaltverharding?

The correct Dutch article is:

de asfaltverharding

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

How to use asfaltverharding

the asfaltverhardingde asfaltverharding
this asfaltverhardingdeze asfaltverharding
that asfaltverhardingdie asfaltverharding
our asfaltverhardingonze asfaltverharding
your asfaltverhardingjouw asfaltverharding
every asfaltverhardingelke asfaltverharding
which asfaltverharding?welke asfaltverharding?
a big asfaltverharding / the big asfaltverhardingeen grote asfaltverharding, de grote asfaltverharding