As you progress throught the rounds using C4 you just might destroy most of the usable cover. To combat this effect I've added the option to add more objects to the map. This option is available during the downtime between rounds.
You can place...
sandbags_big
sandbags_big_curve
concretebarrier
jersey_barrier
hesco_bastion_big
hesco_bastion_small

These can be placed anywhere on the map, rotated and then locked in place. You can also delete objects you previously placed.

Use these to build defensive positions and in your statigies.