When you say 3/4 minus , Is this crushed shale or is it the 3/4 minus that many of the rock pits sale around here ? There is a huge difference in the quality of how well river pit run rock will hold up on a sloped driveway versus crushed shale . I get my crushed shale at North Slope on Hwy. 238 , ( it's about 3/4 mile west of the top of Jacksonville Hill as you go from Jacksonville towards Ruch ) . The problem with river rock 3/4 minus is much of the rock is round , in addition to the fines , ( which is basically sand ) , all of which , although you can roll it and compact it , It still wants to travel or shift .
My crushed shale driveway , ( 800' + ) starts out flat , then progresses uphill at an increasing pitch till the top . We just had it top again last summer with a 3" to 4" cap , no rolling or compacting , and it holds up great even when I turn my Bobtail Semi ( Semi without a trailer ) around at the bottom and back up the drive . With out a trailer , Semi's are pretty light in the back , so they have a tendancy to spin , yet I have yet to tear up the driveway or create any wash boarding effect . We have ours capped every 4 or 5 years , which usually equals about 3 to 5 loads depending on what else we have done .
This driveway is shared by 2 households , so it gets lots of travel .
The sealing that you are refering to is a process that the Forest Service uses around here in that they use various oils ( usually organic and last I heard it was like Banana oil or something ) to seal the rock . Not sure how well it would work on river run rock , since as I mentioned , that rock shifts on slopes , were as the Forest Service also uses crushed shale on their roads . Once they rock or grade a road , they then block it off to keep traffic off for 24 to 48 hours , spray the oil and let it cure . This is usually done on roads that are going to be seeing alot of traffic in the near future like for maintanance or logging operations to keep the dust down and to keep the road in better condition . It kind of acts like a glue , in that , once cured , it holds everything together pretty solid . Even though my better half and neighbors better half are both lead foots , we don't get much dust from our shale even with the driveway being a straight shot up the hill . Have looked at having it sprayed , which you can also buy the oil yourself and do , but once sprayed , you cannot use driveway for something like a minimum of 24 hours . Personally I have no plans on walking up my driveway any time soon .
Fred H.