How to Harden Pea Gravel
A pea gravel path always looks attractive in a garden. The problem, however, is that it won’t keep its shape too well, and needs constant raking and reshaping. Hardening the pea gravel can solve the problem, and will also make a firmer surface for walking, which can be an advantage to people who aren’t too sure on their feet.
Step 1 - Frame
Hardening the pea gravel means mixing it with concrete. The best way to do this is to let it harden in a frame before laying it on the ground. To make the frame, cut the 2x4 lumber so you have 2 lengths of 24 inches and 2 lengths of 25 inches. These need to be put together, so that the same lengths are opposite to each other, the thinner edge uppermost. Nail them together.
Lay the frame you’ve made on a piece of plywood and trace around the outer edges. Cut out the area you traced and nail it to the bottom of the frame, so you now have a box without a lid.
Step 2 - Pea Gravel
In a mixing bucket mix concrete and pea gravel, with 2 parts pea gravel to 1 part concrete. Add water according to the directions that come with the concrete. You should have a mixture that's the consistency of rice pudding. Make sure that it’s thoroughly mixed together, and then line the box you’ve made with wax paper. This will make it easier to remove the gravel later.
Step 3 - Box
With your trowel, empty the pea gravel and concrete mix into the box. Tamp it down to ensure there are no air spaces, and level it out at the top. At this point, you need to set it aside for the concrete to harden. If you want to be able to work more quickly, construct 2 or even 3 of the boxes. This will allow you to harden greater quantities of the pea gravel at one time, so that you’ll be able to complete the path much sooner.
Step 4 - Laying the Block
After the concrete has hardened according to the directions on the pack, which should be about 3 hours, remove it from the box. The wax paper will help you. Stand the box on its side while holding the open face, and tip the box so that the pea gravel/concrete mix is aimed toward the ground. The block should just slide out. If not, tap the bottom with the trowel to loosen the block.
Lay the block where you want it. Make more blocks until you’ve created the full length of the path. If you want a path of small dimensions, you only need to adjust the size of the box forms that you make. Expect to take a weekend to create a path with this method, mostly because of the hardening time of the concrete that’s involved.