Path of the Juggernaut

Those rare barbarians who learn to correctly wear heavy armour are a truly devastating foe. They blitz through the battlefield like a meteor, easily able to turn aside blows from some of the mightiest warriors and return them in kind. One might assume that such thick armour would slow down these warriors, but their raw strength allows them to carry such protection with ease and their fury burns away any sign of fatigue. To try to stop a juggernaut would be like trying to move a mountain or outrun a tornado, for a juggernaut in motion is a force of nature

Armoured Titan

At 3rd level you gain proficiency with heavy armour. In addition you may use your rage class feature while wearing heavy armour.

Unstoppable force

From 6th level, if you move 10ft in a straight line during your turn, you add your momentum to the attack. Make a single attack roll, if successful you may add your Constitution modifier to the damage. In addition the target must succeed a strength saving throw or be knocked prone. The DC for this saving throw equals 8 + your Strength modifier + your proficiency bonus

For each additional 10ft moved during the same turn you may add your Constitution modifier to the damage an additional time, and increase the save DC by +1.

Colossal might

From 10th level you count as one size larger when determining if a target that is your size or smaller can grapple you, in addition you count as one size larger when checking if you can grapple a target, e.g a small creature could grapple medium and large creatures. When moving a grappled target, you do no suffer any movement penalties if they are your size or smaller.

Immovable object

Beginning at 14th level you may add your Constitution modifier to any save roll you are required to make. 
Additionally, when subjected to an effect that would move, knock you prone, or both, you can use your reaction to be neither moved nor knocked prone.