Josephus, doesn't it make you wonder why ZEN would even put forward the idea of supplying graphene for ordinary concrete?

One tonne of concrete costs about $70 on average. There are 2200 pounds/tonne, therefore 16 X 2200 = 35,200 ounces. At .02% by weight, there would be 7.04 ounces graphene per tonne of concrete. Even at $10 an ounce, it would still double the price of the concrete.

1 yard of concrete wighs about 4050 pounds, or 64,800 ounces. Using the same .02% by weight, there are 12.96 oz/yd of concrete. You have indicated that $312. would be manageable per ounce graphene. But at 12.96 oz/yd, that would add $4043 per yard to the cost. That would take the cost/yd from your current $2500 to $6543. 

Both of these calcs have ZEN's selling price being a (small) fraction of the $1000-$6000/oz that Glorieux included in his interview. And there has been no word at all of the costs of graphene production for ZEN, so there is no way of knowing what price ZEN will need to sell their graphene for to provide a healthy margin.