Had to add my reply here. I work in a Soils mechanics laboratory. We determine what compaction is needed and the rate of settlement on construction projects. Depnding on the lay of the land, and your soil type you may not need to get rid of 8'10" of soil. First and foremost is to correct any drainage problems before starting on your pad.
You may have to ditch or trench to redirect the water away from your pad. Save this material. Now remove your top soil with any organic material from the pad area. You can build up your pad area with soil (cheaper than gravel) (any soil as long as it doesn't contain organics). I would suggest using a plate tamper here you can rent one faily cheap. Compact in layers(lifts) no greater than 2-4". Sprinkle with water as you compact. the water addds in achieving maximum density. I would suggest using a landscape fabric on top of your earthen pad. Now you can add your gravel here. A word of caution, You do not want a pourous pad under your concrte when you pour. The water will drain out of the concrete from the under side and be weak. You should have enough fine material to compact your top layer very hard. THe organic topsoil you removed from the pad area can now be used around your pad to achieve the proper grade for drainage away from the base. Plastic can be added added underneath the slab before the pour. This will help your slab cure slowly. If you do a monolithic slab my suggestion would be to use rebaron the edges and thicker members. When curing your pad, let it dry slowly. Concrete reaches maximum strength in 28 days. The greatest strength is achieved in the first 5 days. Don't use any deicing salts on concrete for the first year or it will spall. Sorry about the long post but I really like to see a job well done that looks good and last forever. Most concrete cracking can be attributed to drying to quickly or a poor foundation (not enough compaction). You tractor doesn't exert enough compaction if you are more than 4 inches thick. Use a plate tamper, you won't be sorry.

Reply

Quote Reply

Digg It

Del.icio.us