I think that most people consider "dirt" to be the stuff near the surface that's composed mostly of decayed organic material, not the gravel from smashed up stone from below. Under that understanding, no, dirt does not make good concrete. Bring on the sand, the aggregate, and the cement paste.Most concrete these days can be comprised of up to 25% sand and 50% aggregate - while the sand is "engineered" in the sense of particle size and quality, "dirt" does make good concrete.
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