@aart , clay will turn into concrete when is gets wet and worked, whether there is sand in it or not. Clay will turn into concrete whether you put straw in it or not. The best soil to grow crops in is loam, a mixture of sand, clay, and organic material. If you get the proportions right it is very friable. That means it has a good texture. It can still form a bit of a crust or set up some when it gets wet but nothing as bad as pure clay.
Adobe brick makers put straw of other fibrous material in the clay because clay tends to shrink and crack when it dries. The straw or other fibrous materials help keep it from cracking Adobe brick is sun-dried.
Brick makers and potters put sand in bricks because by itself the clay shrinks when it dries. They add enough sand so the bricks keep their shape when they go into the kiln to dry so you get uniform bricks. The clay turns hard because the kiln gets hot enough to melt the minerals in the clay. That's one reason most brick are red, iron melts at a lower temperature than most other common minerals so it is more economical to heat the clay hot enough to melt iron than some other minerals that would color the brick a different color.
The reason clay sets up so hard is the electrical attraction on the molecular level. Clay is very active at that molecular level, sand is inert. That's what sand does not set up hard, You can pour a bucket of wet sand, try that with wet clay that's had some time to set up. The size of the particles has something to do with it. Clay particles are tiny compared to sand particles so the clay can fill in the voids. My run or garden does not get hot enough to melt the minerals in the clay, it's the molecular attractions between clay particles that cause it to set up so hard when I work it when it is wet, or the chickens work it.
Do some research. Don't take my word for anything, I'm just someone on the internet. I don't know any brick makers but I do know a couple of potters, one a true artist and the other very knowledgeable of the basics. Research online was a bit challenging, I'm probably not setting up the searches right. I took soils mechanics in college many decades ago so while it's been a while I do understand the basics on a molecular level. I spoke to one extension agent that was "Oh!! Sand in clay!! Oh!! Oh!!" Another one said the best ratio for a garden soil is 2 part sand, 1 part clay, and a lot of organic material (compost). I need to add more clay and more compost to my raised beds, they drain too well.