Last weeks I worked with very raw materials: petrified earth, field stones, stones that have crumbled into earth, gravel and lots of beton. We built a floor in a part of an old cave, about 28 square meters. We chopped out a lot of earth and stones (because over the years, some of what was stored on the ground dissolved into some kind of soil), transported most of it into our garden as a foundation for a new vegetable bed, levelled the ground with gravel and concreted the ground.
I have to submit I like working with concrete, as I do with sand and lime and since a few weeks, bitumen.