Finally I and my husband decided to make laundry room in basement. Currently unfinished dirt floor in the room. What is the best and cheap solution (can be gravel and concrete?)? Thank you!
Concrete will be best, but you will have to properly compact the soil, lay the proper sub-base for drainage, have a vapor barrier, and pour the correct concrete mix atop the above. If not, you may end-up with a floor that looks great but slowly allows moisture to penetrate your new concrete flooring and rust your appliances. In other words, seek and install a properly engineered floor to save you years of potential grieve.
If you went with gravel you'd have severe rusting issues with the washer/dryer due to the ground moisture coming up through the gravel.
Concrete would be the best, making sure a drain is installed in the floor too.