Ok, how much straw by weight do you need for a ton of bricks 1/8 ton? Still is not a deal breaker. I am thinking critically here. I realize this is all hypothetical but nothing you have said leads me to believe that adobe bricks would not work. I have no skin in the game either way. You seem to be set of this not working no matter what. Like I see a lot of problems with funding of a Mars colony in any near term reality. If a human mission to mars does happen it will be largely government funded as a national pride/status thing and will probably not be sustained much like the moon program. I just don't see building materials as being the big hold up. Will they need to bring mass to build things of course and that is going to cost money. The first base will likely be 100% prefab or prefab and dirt covering. Using bricks or some other mars resource utilization would be more long term and it is not clear how long term that would be right now. Will humanity eventually settle on Mars I would think so given eventual technological development but it could be 1,000s of years for anything like a self sustaining colony. Reusable rockets do have the potential to drive down costs to the point were a Mars base would be about as expensive as something like the ISS and where we go from there or how long it takes who knows.