Do not use crushed limestone, it is about 50% calcium carbonate.
You can use play sand or some other type of sand, it is about the same size. Chick grit or sand will only be effective as grit for chickens to about 3 weeks of age so by 7 weeks thay can take #3 size adult grit.
This is from the TCC Materials website.
What size poultry grit do I need?
Cherry Stone Poultry Grit comes in four pre-sorted size options:
Poultry Grit #1 is the smallest with average size of 1/16”. It is best for turkeys age 1-5 days or chickens age 1-3 weeks
Poultry Grit #2 averages 3/16”. Recommended for turkeys age 6-21 days and chickens age 4-6 weeks
Poultry Grit #3 averages 5/16”. Recommended for turkeys age 3-8 weeks and chickens age 7+ weeks
Poultry Grit #4 averages 3/8”. Recommended for turkeys age 8+ weeks
When deciding between sizes for your birds, it is usually better to select a larger size than smaller.
To be effective as grit, it must be sharp insoluble stones like flint or granite.
