It basically takes three steps to turn agave bagasse into a building material:

They physically remove the alcohol, sugar, bone, and shell, so just the fiber remains.

They dry the remaining fiber, then pulverize it into a powder.

They add a compatibilizing agent to make the powder behave like a plastic and interact well with the recycled plastic.

via Eat Drink Better | Healthy recipes, good food: sustainable eats for a healthy lifestyle!.