free concrete ?
I had a good friend, ( Killed in a car wreck last year ) .he had a 1 ton flatbed dump and contacts with a local concrete company, He could get concrete left over and brought back to the yard for free. they would call him and he would throw a plastic tarp over the cab and bed and they would dump it in the back / He would use it for non structural things on his 5 acre place. A concrete vibrator really helps to be able to work it. He brought me 2 loads last year. we poured a sidewalk in front of the shop and from the shop tp the house. It was HARD work since we were building forms and pouring at the same time. watered down concrete left overs won't be as strong but better than rocks.