For best results, lay stone walkway on reinforced concrete base
The small loose stones between the pieces of rock can cause a mess. (Ron Bergnal / May 31, 2013)
DEAR RON: I'm quite sure I can help you with this project as I've got lots of experience creating walkways using brick, stone and other masonry materials. Perhaps you can learn best from my failures and successes.
When I was a greenhorn in the construction business, I decided to install a gorgeous brick sidewalk at the second home my wife and I rehabilitated. Back in the 1970s, home improvement television shows were in their infancy, and I watched a show where a man said to just lay the brick in coarse sand. All you had to do was level the sand, butt the brick against one another and sweep fine sand between the cracks in the brick.
That seemed like a great idea, and it was most certainly easier and less expensive than putting the brick down in concrete or on a gravel base. I proceeded with the job and it really came out looking spectacular.
But then I discovered that the bricks would shift at the edges, sand would track constantly into the house and weeds growing between the brick were a constant nuisance. In other words, my new brick walkway was a disaster.
A few years before, I had installed a brick walkway and path for my future mother-in-law using a very different method. I blended coarse, damp sand with Portland cement, spread this mixture about 3 inches thick, leveled it and then tamped it. I then butted the brick on top of this and swept the cracks with fine sand mixed with Portland cement.
That patio, to this day, still looks fantastic. It was a grand success, and only a few of the edge bricks ever popped loose. The few weeds that grew in the cracks were easily removed or treated with weed killer.
My best stone and brick walkways involved more work, but 30 years later they look the same as the day I installed them.
I discovered that if you want really professional results, you install the stone or brick on top of poured concrete that contains reinforcing steel. The reinforced concrete creates a solid foundation for the finished stone or brick so that it resists frost heave or other ground movement.
I would mortar the brick or the stone to the concrete slab with regular mortar made from medium sand and Portland cement. The mortar bed was usually only a half-inch thick. I would mix three parts sand to one part Portland cement for this bedding mortar.
The spaces between each piece of stone or brick was filled with extremely strong mortar made from clean sand and lots of Portland cement. I wanted a mortar that would possibly last 50 to 100 years so that I wouldn't ever have to worry about tuckpointing it.
I would estimate that the compressive strength of the mortar exceeds 8,000 pounds per square inch because it contains so much Portland cement. I made this mortar by mixing one part sand to one part Portland cement. It was extremely rich in cement content; fortunately, a bag of Portland cement is not really expensive.
As for trimming the stone, I discovered that you could use a tired old circular saw equipped with an abrasive masonry blade to create crisp cut lines in both brick and stone. If you desire the more rustic hand-chipped look on the edges of the stone, you can use the saw to make a score line on the bottom of the stone just under where you want the jagged line to appear.
Cut the stone at least halfway through its thickness and then tap the top side of the stone with a hammer along the line you want to create. This should produce an acceptable jagged line when the stone splits off.
Installing stone, brick or any other finished masonry material on top of a poured concrete base is lots of work. When I watch the modern television shows that show the fast and easy method, I usually chuckle because the young people on camera remind me of myself when I thought it was a grand idea to take the shortcut placing the brick in the sand.
If you do decide to place your stone on top of a concrete base, don't spend the time to put a smooth finish on it. You want the concrete to be in the same plane with no humps in it, but a simple screeded finish with some holes in it will do just fine. The coarse finish helps hold the bedding mortar to the concrete.
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