Friday, September 20, 2013

Nopel Patio Hardening

 September 14, 2013

Several of our shelters have a raised platform (or "patio") under the front overhang because of the slope of the ground where the shelter has been sited.  Picnic tables are placed under the overhang, not only for hiker's convenience, but to deter fires from being built directly in front of the shelter--so this patio needs to be reasonably level, pitched slightly for drainage.

Rock walls, or occasionally, wooden cribs are constructed, then filled with mineral soil taken from nearby borrow pits.  Because the patio is somewhat protected from the weather, the mineral soil never gets very wet and can be easily tracked into the shelter by hikers--especially when their boots are already wet.  Locations with sandy subsoils are particularly prone to this problem.  Earlier, we addressed the same issue at Wilcox South shelter  This post goes into a little more detail.

To remedy this, after the original patio has been used for a couple of years, we consolidate the mineral soil by mixing in cement and spread the mixture evenly over the surface and water it lightly.  The chemical reaction in the cement helps bond the dirt together creating a more durable surface.  Because the top coat has little structural strength, the soil underneath must be well-compacted. 

It starts with dirt.  Don harvests from the borrow pit.

3 parts mineral soil to one part cement.  Jim mixes small batches of the dry ingredients    

Dry mix is spread over well-compacted patio surface

Low spots are filled and lightly tamped with a rake

Jim and Steve use a screed board to make a smooth, flat surface

Surface is lightly watered

It sits for about a day while the mixture sets and dries.

1 comment:

  1. Last Friday I took a walk over Mt Greylock to Cheshire and stopped in to see how our patio hardening worked out. I found it had hardened nicely and with the help of a south bound thru hiker we set the picnic table back up on the patio.