Poured Concrete Pathways

How to Pour a Concrete Pathway

1. 1 Lay out edges with stakes

   

   Lay out the precise edges of the finished walkway using stakes (or batterboards) and mason’s string (see pages 38 to 39 for additional help with setting up and using layout strings). Where possible, set stakes 12" or so outside of the walkway edges so they’re out of the way. Make sure any 90° corners are square using the 3-4-5 measuring technique. Level the strings, and then lower the strings on one side of the layout to create a downward slope of 1⁄4" per foot (if the walkway will be crowned instead of sloped to one side, keep all strings level with one another: see page 39). Begin the excavation by cutting away the sod or other plantings 6" beyond the layout lines on all sides of the site.

   
   

2. 2 Excavate and tamp soil

   

   Excavate the site for a 6"-thick gravel sub-base, plus any sub-grade (below ground level) portion of the slab, as desired. Measure the depth with a story pole against the high-side layout strings, and then use a slope gauge to grade the slope. Tamp the soil thoroughly with a plate compactor.

   
   

3. 3 Adding gravel

   

   Cover the site with a 4" layer of compactable gravel, and then tamp it thoroughly with a plate compactor. Add 4" or more of gravel and screed the surface flat, checking with a slope gauge to set the proper grade. Compact the gravel so the top surface is 4" below the finished walkway height. Reset the layout strings at the precise height of the finished walkway.

   
   

4. 4 Building the wooden mold/form

   

   Build the concrete form with straight 2 × 4 lumber so the inside faces of the form are aligned with the strings. Fasten the form boards together with 3 1⁄2" screws. Drive 2 × 4 stakes for reinforcement behind butt joints. Align the form with the layout strings, and then drive stakes at each corner and every 2 to 3 ft. in between. Fasten the form to the stakes so the top inside corners of the form boards are just touching the layout strings. The tops of the stakes should be just below the tops of the form.

   
   

5. 5 Creating curved corners

   

   Add curved strips made from hardboard or lauan to create curved corners, if desired. Secure curved strips by screwing them to wood stakes. Recheck the gravel bed inside the concrete form, making sure it is smooth and properly sloped.

6. 6 Reinforcing and coating the form

   

   Lay reinforcing wire mesh over the gravel base, keeping the edges 1 to 2" from the insides of the form. Overlap the mesh strips by 6" (one square) and tie them together with tie wire. Prop up the mesh on 2" wire bolsters (“chairs”) placed every few feet and tied to the mesh with wire. Install isolation board (see page 37) where the walkway adjoins other slabs or structures. When you’re ready for the concrete pour, coat the insides of the form with a release agent or vegetable oil.

   
   

7. 7 Begin to pour concrete

   

   Place the concrete, starting at the far end of the walkway. Distribute it around the form (don’t throw it) with a shovel. As you fill, stab into the concrete with the shovel, and tap a hammer against the back sides of the form to eliminate air pockets. Continue until the form is evenly filled, slightly above the tops of the form.

   
   

8. 8 Immediately screed surface

   

   Immediately screed the surface with a straight 2 × 4: Two people pull the board backward in a side-to-side sawing motion, with the board resting on top of the form. As you work, shovel in extra concrete to fill low spots or remove concrete from high spots, and re-screed. The goal is to create a flat surface that’s level with the top of the form.

   
   

9. 9 Isolation board Optional

   

   Option: Cut an isolation board and glue it to the existing concrete structures at the point where they meet the new sidewalk. Steps, foundation walls, driveways, and old sidewalk sections  are examples of structures you’ll need  to isolate from the new concrete.

   
   

10. 10 Float surface

    

    Float the concrete surface with a magnesium float, working back and forth in broad arching strokes. Tip up the leading edge of the tool slightly to prevent gouging. Stop floating once the surface is relatively smooth and has a wet sheen. Be careful not to over-float, indicated by water pooling on the surface. Allow the bleed water to disappear and the concrete to harden sufficiently.

    
    

11. 11 Use edger

    

    Use an edger to shape the side edges of the walkway along the wood form. Carefully run the edger back and forth along the form to create a smooth, rounded corner, lifting the leading edge of the tool slightly to prevent gouging.

    
    

12. 12 Mark joint locations

    

    Mark the locations of the control joints onto the top edges  of the form boards, spacing the joints 11⁄2 times the width of  the walkway.

    
    

13. 13 Cutting control joints with groover

    

    Cut the control joints with a 1" groover guided by a straight 2 × 4 held (or fastened) across the form at the marked locations. Make several light passes back and forth until the groove reaches full depth, lifting the leading edge of the tool  to prevent gouging. Remove the guide board once each joint  is complete. Smooth out the tool marks with a trowel or float.

    
    

14. 14 Create a nonslip surface

    

    Create a nonslip surface with a broom. Starting at the far side edge of the walkway, steadily drag a broom backward over the surface in a straight line, using a single pulling motion. Repeat in single, parallel passes (with minimal or no overlap), and rinse off the broom bristles after each pass. The stiffer and coarser the broom, the rougher the texture will be.

    
    

15. 15 Cure concrete, cover in plastic, let dry

    

    Cure the concrete by misting the walkway with water, and then covering it with clear polyethylene sheeting. Smooth out any air pockets (which can cause discoloration), and weight down the sheeting along the edges. Mist the surface and reapply the plastic daily for a few days.