Im a former Design and Technology High School Teacher. My degree major/minor is Industrial Technology and Design. I seriously have a bit of an issue with the term “mud” in the way in which it appears to be defined by some here.
My hope is that most do realise that without any kind of binding agent, mud will not form brick.
Straw is not a binding agent as such…it basically provides reinforcing…it is not glue.
Another example…steel reinforcing in concrete plays absolutely no part in the gluing of the various elements of concrete together. That glue in the concrete is a combination of clay and cement (fired lime) Steel is simply a substitute for straw…one that has far better tensile strength.
The “mud”, must contain a binding agent such as clay to glue the grains of sand together around the straw. Without this binding agent, it will simply crumble as soon as the sand dries out…even whilst its wet it wont bind adequately enough to build a brick structure like a wall.
perhaps I’m jumping to conclusions, however, just want to make sure that point is front and center because there seemed to be a lot of focus on making sand castles! These work on the beach only for a very very short period of time and that is because they don’t have any real binding agent. They have almost no capacity to hold weight (when compared with a properly made brick), and once hit by water or they dry out…the erosion is extremely rapid.