gravel road with Portland cement
I have an architect that wants me to build a winery a road. He doesn't want the look of pavement or the expense of concrete. So he wants me to put down a 6" 21A base (crusher run) and 3" of brown pea gravel, then spread 100lbs of portland for every 2 lineal ft. I am looking for any tips on how to make this work. The architect wants a hard road with that brown gravel look. I don't see how the portland is going to hold the brown gravel. So should I put the portland on top of the 21A base and then roll and vibrate that, then go with the pea gravel? Also on a 12' wide road do you guys think it is critical to crown the road with 2 ditches or have positive drainage across the whole road and into one ditch? Thanks for your advice.
Originally Posted by Jim Dandy
Your best chance to make the Portland scenario work in my opinion would be. Get your material(s) and process them together through a Pug Mill, adding the optimum moisture at that time.
I would construct your subgrade with a super elevated profile... a crown is going to be too difficult to accurately construct on a road this narrow, furthermore, most likely there is nothing that would require it. I would place this material with a paving machine; I think this would be the most effective at achieving the results you specified. You could also place and grade it with a grader and use a roller and possibly get the 3/8" pea gravel worked to the top for the desired appearance.
I think the Pug Mill will process the materials more effectively than anything short of having a batch plant mix up some 1 or 2 sack slurry.
Running aggregates through the augers on a paving machine for extended periods of time is hard on things due to the fact there are no oils to help lubricate as there is with asphalt.
See my article on road maintenance where I talk about crowns versus super elevated road designs.
I would run the numbers on the aforementioned options and see how they stack up? I am anxious to see how you proceed.
Anytime I've mixed cement into the topcoat of a gravel road it broke out in slabs. If there's no frost going in and coming out you may be okay, but frost will kill it in short order.
i see the problem they have an( architect )
That's funny right there!
Originally Posted by mrkw77
During the late 90s I was working in the Portland Oregon area. A company by the name of Baker Resources sold a product called S.T.B. which consisted of basically 3"- rock, overburden and lime. All of which was mixed in a pugmill.
It was intended for use as a subgrade material for streets in new subdivisions and worked so well that Washington County made it a requirement on all new public roads and street
improvement's. We would place a minimum of 12" with up to 36" depending on existing soil moisture content.
Final subgrade was then accomplished by placing 6" of normal 1"- on top of the S.T.B.
S.T.B. looks like dirty brown rock which holds up perfectly fine on its own in the wettest conditions and was often placed in the rain simply by excavating only what could be backfilled by the next round of trucks.
Oftentimes we would place S.T.B. in late fall or early winter which allowed pipework to continue through the rainy season.
Pretty amazing stuff that was much more cost effective at the time than regular crushed spec rock.
Ought to be a law against architects doing civil work.
Agreed, I just can't see how a 3" layer of what is basically a substanard Portland-based concrete with no reinforcement is going to stand up to any traffic. It will be too weak to hold its shape if you will, and to brittle to flex under load.
Originally Posted by ben46a
I don't know about how it is working with this architect, but what about a chip seal surface as an alternative? The oil base will allow some flex and the top coat of rock will maintain the look of gravel especially if it is not all broomed clean after building it. It's done all the time around here.
Another thing I just noticed... 6 inches isn't near enough of a base in most cases, especially if he wants to cap with concrete; unless its or something quite hard and stable already (not soil or clay)