What? It’s extremely unclear what your concrete (ha) questions are. Your questions (while clearly well-meaning and well-intentioned, and probably from a perspective that most people in this discussion generally agree with, including myself) seem generally too broad and disconnected from the more detailed discussion of materials. You mentioned you can’t see the other side of the argument, but it’s unclear what exactly you are arguing for or against in relation to reclaiming cement from concrete versus down cycling concrete into roads. It’s unclear to me what environmental concerns you are talking about that directly relate to the discussion above.

There are all sorts of ecological/environmental/social concerns at various stages of the concrete lifecycle, but certainly at a global scale one of the most significant effects is the contribution to climate collapse associated with cement production for concrete (around 10% of global emissions). Concrete however is certainly not going away though as it is one of the primary structural materials in most of the world, especially in parts that are rapidly expanding the building stock, and so doing everything we can to mitigate the resulting carbon emissions is essential, as those emissions pose a dire threat…

My question was directed at the downvoter.