Compaction Confusion? We understand: It is a bit of an art form!
The moisture content must be just right for the material (D.G. or Base) to get properly compacted. Too much water and the material will just get pushed around like mud. Too little water and material will not take compaction and stay loose.
Here are a couple of images that show what freshly installed, well compacted material looks like. The larger aggregate pieces get pushed down into the fines for a smooth hard surface.
We find it helpful to refer to these instructions for Stabilized Decomposed Granite:
Pre-blended stabilized decomposed granite provided by Decorative Stone Solutions should be installed using the following instructions as a guideline.
1) For pedestrian or equestrian surfaces the binder shall be blended at the rate of 10 lbs. per ton of granite fines and shall be placed to a minimum depth of 2”-3" compacted. For parking lots or roadways the binder shall be incorporated at the rate of 14 lbs. per ton and shall be placed to a minimum depth of 4" compacted.
2) Prepare the sub-grade by compacting native soil as much as possible for pedestrian use. For heavy vehicular traffic, consider a 4” base of wet and compacted Class 2 roadbase. Pre-soak base material with water prior to installing stabilized D.G..
3) Select and install a desired border material on peripheral edges of area to be paved which aren’t already adjacent to a solid surface. Some suitable materials include: Pressure treated lumber, secured masonry/stone units “block, brick, ledgestones, and cobbles”, as well as various landscape edgings capable of withstanding lateral forces of compaction.
4) Due to inadequate moisture penetration, applications of stabilized D.G. more than 3”must be installed in lifts. If stabilized D.G. is pre-moistened, such as in a drum type mixer, entire 4”-5” lifts may be installed in a single application.
5) Place the stabilized D.G. on the prepared subgrade, and rake smooth to desired grade and cross section. Place material to sufficient depth to allow approx. ¼” of compaction for every 2” of loose D.G.
6) Thoroughly water entire surface so as to achieve full moisture penetration. Water is the activation mechanism for the stabilizer. During water application test water penetration depth with a probing devise. *Do not underwater, it is not possible to over-water this product, it will however extend the set up time before compaction can take place*
7) Installer shall wait a minimum of 6 – 48 hours or until such time that the paving material is able to accept compaction from a 1 to 5 ton roller/compactor without separation, plowing or any other physical compromise of the paving material. Compact the material with compactor as specified above making 3 to 4 passes. Avoid a vibratory plate compactor when possible, however tight spaces may mandate the use of a small handheld unit.
a ) Remove debris, such as paper, grass clippings, leaves or other organic material by mechanically blowing or hand raking the surface as needed.
b) During the first year, a minor amount of loose aggregate will appear on the paving surface. If this material exceeds a 1/4", redistribute the material over the entire surface. Water thoroughly to the depth of 1”. Compact with power roller of no less than 1000 lbs. Repeat process as needed.
c) If cracking occurs, simply sweep fines into the cracks, water thoroughly and handtamp with an 8” – 10” hand tamp plate.