this would vary greatly depending on the type of soil, temperature, moisture content, etc. and the specifics of the construction that you are doing. A geotech, on-site should be consulted to give this advice.
Engineered fill cannot be placed on frozen subgrade and frozen soil cannot be used.
You can wait for warmer weather or you can place all frozen material in a stockpile for use later in the year; and yes this means that you have to strip the site every morning of all frozen material and waste it.
We have done quite a bit of site work in the winter. It is more expensive than in season work. Significantly. I do not know of an industry standard except that you can not place frozen material or backfill on frozen ground. (even this is not completely true - stay tuned) When the ground freezes, the water in the soil swells (Water is about the only liquid that is less dense as a solid than as a liquid. The ice will prvent compactive effrotrt from densifing the soil. When the ground thaws, the soil will settle.
Techniques for winter site work:
1. Don't do it unless you have to.
2. Try to open as small an area at a time and fill it as soon as possible.
3. Subgrade can be thawed using ground heaters. These heaters have long hoses taht can be stretched out. The hoses circulte hot liquid which will thaw the ground. They are expensive not only to rent but also to operate.
4. Frost will penetrate a few feet. This can be dug out and stockpiled. Once the frost is dug out work quickly as this face will begin to freeze. If it is left open at night, it might be protected using concrete blankets.
5. The backfill should be clean gravel or crushed stone. I like 3/4 in. stone. If using gravel, try to get the cleanst you can as it is the fines that cause the greast problem with frost. Keep the exposed face of the pile as small as possible. Dig into the pile and remove any surficial frozen ground. I prefer crushed stone as it will not freeze nor does it need compaction.
6. If you do not have any need for compaction, you can place frozen material onr have frozen subgrade. Just note that if this material is placed, it should be proof rolled in spring and readjusted.
Here is a caution that can bite you if you miss what is going on,
Granular fill, in a low moisture condition, not sturated,can be below the freezing point and you will not know it is frozen by physical means, such as digging it, kicking, etc. the moisture will freeze on the grains and won't be noticed.
Put the stuff in and compact it. Then run an inplace density. You will not achieve a reasonable degree of compaction.
If you don't do any tests, later on when things melt, you will see settlement.
This problem can happen using the clear stone mentioned above also.
For a general rule when working in winter, even using apparently unfrozen material, is don't expect any reasonable progress if temp. is below 20 F. Below zero nothing works.
We have used the clean stone frequently in very cold temperatures. Sub zero, we don't work. Actualy you get around 10 and it is not a good idea to be out there. however, if there is moisture and the stone is frozen, hard it can be a problem. Typically, the material breaks up upon handling and seems to be okay, but I see your point and would conceede that under some conditions it might be a problem.
