By Michael Swiderski, Ph. D.More in Blog Cabin
Using string, sand, stakes, a framing square, a hose or any other creative tool, outline the shape of the area being covered in concrete.
Wooden concrete forms hold the liquid cement in the desired shape for the base. Create straight runs from economy grade, or scrap 2x4s. Use 1/4” exterior plywood or tempered hardboard for curves. Drive wooden stakes (grade stakes) into the ground and screw to the wooden forms.
Builder's Tip: Building concrete forms is not a finished carpentry project. Strength is more important than good looks, so brace the forms well. Stakes secure the straight runs every 2' to 3'. Stake the curves every 18”. Keep both sides of the form tops level.
To assist in leveling the concrete once it is poured, the forms may be built with both top sides being level so a screed board can “skim” the top and level the concrete.
Reinforced wire mesh may be needed (check with your concrete supplier). Cut the reinforced wire mesh with a heavy-duty wire cutter and lay it on the ground, inside the forms.
Order the concrete truck, if pouring over a yard. If a small amount is needed, rent a cement mixer (which is different than a mortar mixer).
Builder's Tip: Concrete is a mixture of sand, course aggregate, Portland cement and water. The sand used in concrete should be blank-run sand, which is fairly round in shape and of various sizes. The course aggregate is gravel or crushed stone. The aggregate pieces should be no larger than 1/4 the thickness of the pour. Portland cement is made of clay, line and other ingredients that have been heated in a kiln and ground into a fine powder. Choose Type I cement.
If mixing the concrete in a DIY fashion, read the cement bag carefully for proper ratios of cement, sand, aggregate and water.
If the concrete comes from the truck, use a shovel or rake to maneuver the liquid cement inside the forms. Climb inside the forms, wearing rubberized mud boots to help evenly distribute the concrete pour. The truck trough can be relocated to uniformly distribute the pour to different locations within the form. Using the shovel or rake, bring the poured concrete up to the 4” level, or to the top of the forms. A screed board will skim the top and level the pour. If a large area is being poured, the reinforced wire mesh should be pulled up from the bottom into the middle of the 4” pour. Use the tines on the rake to pull up the wire mesh throughout the pour area. Keep the forms in place until the concrete has set (usually 24 hours).
If a large area is being poured, a darby, bull float and finishing trowel will smooth the concrete surface. This surface does not need to be perfect, since it is being covered with bricks and cobblestones.
The brick at Blog Cabin 2011 formed a border around the cobblestone. The possible brick patterns can be discussed when visiting the brick supplier.
Consult the supplier for the best mortar mix for this DIY project. Consult for proper ratios of sand, cement and water. Use a wheelbarrow or cement mixer to blend the mortar mix. Test the mortar by picking up a small amount with the trowel and quickly turning the trowel upside down. If the mortar sticks to the trowel, it is the correct consistency. If the mortar stiffens before being applied, add water and remix.
Pour the mortar into a wheelbarrow or mortar pan. Getting the mortar on the brick trowel may take some practice. Slice off a gob and shape it so it is about the size and shape of the trowel. Bricklayers talk of “throwing” mortar onto the bricks: In one motion, flick the wrist and pull the trowel toward the body. Furrow the mortar to an even thickness. Lightly draw the point of the trowel across the length of the mortar to make a furrow down its middle. Don't make the furrow too deep or an air pocket may be formed. “Butter” the new brick end by scraping the end with the trowel, depositing mortar to “squish” against the adjacent brick. Place the brick so it can slide into place, pushing it firmly up against the preceding brick, allowing the mortar to “squish” out. Tap the brick down with the handle of the trowel to seat the brick. Immediately slice off the excess mortar oozing from the sides. Use this excess mortar as part of the next brick. Continue laying brick, using the 4' level to keep the border level. After all the bricks are laid, take the joint strike or piece of pipe and smooth the joints when they begin to stiffen. Let the brick set overnight before laying the cobblestone.