- How to Prepare Soil for a Concrete Slab
- How to Prevent Frost Heave in Concrete Slabs
- How to Clean a Concrete Slab
- How to Replace Concrete Slab Separators
- How to Excavate for a Concrete Slab
- How to Lift Concrete Porch Slab With Hydraulic Jacks
- How to Build a Wooden Frame Over a Concrete Slab for a Floor
- How to Install Underground House Plumbing Slab Foundation
- Fixing Moisture Problems on a Concrete Slab
- How to Clean Concrete Slabs on a Patio
- How to Lift Up the Side of a Sunken Cement Slab
- How to Calculate the Weight of Broken Concrete
- How to Measure Yards of Concrete
- How to Lift a Concrete Slab
- How to Attach a Bottom Plate to a Concrete Slab
- How to Lay Brick on a Concrete Slab
- How to Make Clocks From Slab Wood
- How to Make a Cutting Board Out of a Tree
- How to Clean Paving Slabs
Concrete is beneficial in the garden and landscape. Offering a solid surface that holds up to rain and traffic, a concrete slab can provide a patio for entertaining, a base for a garden shed or a spot to store anything off the ground. Before you can pour a concrete slab, you must prepare the soil beneath to ensure that your slab remains level and to reduce cracking from unstable soil.
Remove the top layer of soil, including all the sod, with excavating equipment or with a shovel. While soil types vary in different geographical locations, the surface is usually unsuitable for pouring concrete. You may have to remove 5 inches or more of soft soil to reach the hard compacted soil.
Replace the removed soil with sand. Sand compacts well and provides an optimal base on which to pour concrete. The amount of sand you will need depends upon how much soil you removed. A concrete slab may be 4 to 6 inches thick, so add sand until it reaches the proposed bottom of your slab.
Pack the sand with a sand compactor, available from construction rental stores. You will run the compactor over the sand base and the machine will vibrate the sand, forcing the tiny particles to fill in tightly.
Excavate a foot into the ground and compact the soil with a soil compactor, which you can usually rent from hardware stores. This will prevent water from penetrating into the soil as easily and provide a solid base for the concrete slab.
Lay down 6 inches of crushed gravel as a layer between the soil and the concrete, creating a porous area from which the water can drain. Place a 4-inch perforated pipe in the gravel and route it to a dry well, or just outside of the area where the concrete slab is located.
Pour the concrete slab until it is about 3 inches thick. Lay down ½-inch steel reinforcing bars 2 feet apart from one another and then a fibermesh slab. These will prevent shrinking and cracking and strengthen the concrete, making it less susceptible to frost heave. Pour 3 more inches of concrete on top of that to finish off the slab.
Sweep the concrete with a broom to remove loose dirt, dust and debris. Thoroughly soak the concrete with water from the garden hose.
Scrub the concrete briskly with a stiff-bristled non-metallic brush. This will help to minimize the amount of cleaner that will be absorbed into the concrete.
Fill a bucket with a solution of warm water and an all-purpose cleaner. Follow the mildest mixing instructions on the bottle of cleaner. Formula 409, Simple Green and Fantastik are a few examples of all-purpose cleaners.
Scrub the concrete with a stiff-bristled non-metallic brush and the bucket of cleaner. Make sure to overlap your scrubbing strokes to ensure all of the concrete slab is cleaned.
Rinse the concrete promptly with water from the garden hose.
Use the hand shovel to remove the old dividers. If the separators are stuck to the concrete, you may need to use a hatchet or axe to chip off pieces until you can get them out.
Look for roots along the concrete. If you find any, chop them up with the hatchet, as they will prevent you from putting the new separator in properly.
Use the tape measure to find the width and length of the gap between the slabs of concrete. The gap is usually in the 1/4-inch range.
Buy new separators and separator nails. Regular nails will not work.
Put your concrete slab separators in the gaps.
Use a mallet to knock your separators firmly into place.
Hammer the separator nails into the slats. Space them evenly across the width of the area in which you're working.
Check to make sure your separators are not rising above the concrete. If they are, hammer them deeper down with the mallet, then repeat step 7.
Check your local ordinances for building outdoor structures. You may be limited as far as size, placement or type of structure. Make sure you are within ordnance laws before purchasing materials.
Measure out the area for the concrete slab. Shape by placing stakes in the four corners of the area and forming square with string. Check area for square by measuring from one corner diagonally to the other corner. Adjust position of stakes, if necessary.
Shovel down 10 inches-6 inches for gravel and 4 inches for thickness of the concrete slab. Remove rocks and large roots to leave the bottom of the excavated site as smooth as possible. For water runoff, pitch ground 1/4 inch for every foot. Slope away from the house or other outdoor structures.
Use 2-by-10 inch boards to build a form, which holds the gravel and concrete slab in place. Pour in 6 inches of gravel, and tamp down. Smooth out gravel to make a level surface, allowing enough space for the concrete slab to be level with top of the area you want to excavate.
Install 1/2-inch steel bars to form a reinforcing grid for the concrete. You can lay large flat rocks beneath the middle of the grid for additional support.
Place bars every 2 feet from the sides, back and front of the excavated area. Tie where the bars intersect with wiring.
Push the tip of the prybar under one edge of the concrete slab and push a heavy block against the prybar to create a lever. The block can be anything dense and rigid, such as a cinder block or a piece of cut firewood.
Press down on the end of the prybar to elevate the edge of the concrete slab.
Slide the hydraulic jack under the edge of the concrete slab as soon as you've lifted it high enough to create space for the jack.
Release and remove the prybar, allowing the slab to rest directly on the lift of the hydraulic jack.
Pump the jack handle to raise the edge of the slab as high as you desire. If the slab is too heavy to move by hand, move to the other side of the slab and use the prybar and a second jack to elevate the slab.
Pump the handle of the second jack until you have the slab evenly balanced between the two jacks. If the slab is too heavy to carry, wheel it away with the two jacks.
Place a board against one wall. Cut the board with your circular saw so that it fits along the wall tightly. Stand the board on its narrow side so that it stands 3 1/2 inches tall.
Cut a second board to match the first one. Place it alongside the first board. Drive two of your 16d nails through the boards every 12 inches to form a secure double stud.
Repeat the process across the room on the parallel wall. Push each double stud tight against its own wall.
Build a double stud for each of the two remaining walls. Toe nail each perpendicular double stud to the original two double studs to complete the outer band of your frame.
Measure the distance between your last two double studs. Divide that number by 12. Cut that many rows of boards. Nail each of those boards into a double stud. Toe nail one of those double studs to the original two boards. Place one double stud every 24 inches across room.
Find the points on your blueprint where the plumbing will emerge from the finished, concrete slab, and measure the ground to find those precise points with the measuring tape. Mark the points and the path of the underground pipes with spray paint.
Dig trenches about 18 inches down and approximately 6 inches wide along all the marked, spray painted paths with a shovel.
Lay the horizontal pipe into the trenches, and at the point where they should come out of the ground, place the angled pipe fittings on them, angled upward toward the sky.
Cut lengths of pipe with a saw sufficient to attach to the other side of the angled fittings, come out of the ground, and stand at least 8 inches above the finished, concrete surface.
Attach the pipe lengths you cut in the previous step to the angled fittings using PVC glue.
Refill the trenches you dug and tamp the ground so that the only things visible are your vertical pipes coming out of the ground. Be sure refilling the trench doesn't knock the pipes over from being straight.
Allow the slab sufficient time to dry naturally. According to Plant Services, this takes upwards of 168 days in ideal conditions.
Ventilate the area containing the concrete. Ventilation allows the evaporating moisture an outlet, rather than having it hang in the air and fall back onto the concrete.
Use fans or blowers. Moving air is shown to triple evaporation rates.
Apply heat. According to TWResin Technologies, forced air heat works the most effectively.
Dehumidify the area containing the concrete. Removing excess moisture from the air also draws excess moisture from the concrete slab.
Remove all furniture, plants and other items from the concrete slab. Sweep off loose debris with a broom.
Fill a bucket with 1 gallon of water. Add a few squirts of mild dish soap.
Scrub the patio with a long-handled scrub brush and the soapy water. Rinse the soap off with water from the garden hose.
Cover plants, grass and landscaping around the concrete slab with plastic sheeting if it is still dirty or stained. Put on rubber gloves and protective eyewear. Combine three parts water and one part chlorine bleach into a clean bucket. Scrub the patio with the scrub brush and bleach mixture. Let the mixture sit on the concrete for 10 minutes, and then rinse the patio well with water from the garden hose.
Leveling the Slab
Drill a pattern of 1- to 2-inch holes through the sunken cement slab. Place the pattern of holes three to eight feet apart, depending on the size of the slab. Do not place holes within one foot of the edge of the slab.
Pump the grout mixture at the lowest point of the slab. Move the pump to the next lowest point as the slab rises one inch. Once all the holes are injected, move the pump back to the lowest point and continue the process until the slab is at the desired level or height.
Fill the drilled holes with concrete. Mimic the texture of the slab to hide the holes.
Measure the space the concrete was taken from. Note the length and width of the slab area. Measure the depth of a piece of the broken slab to determine the depth of the slab itself. These measurements will allow you to figure out the volume of the concrete before it was broken.
Multiply the length, width and depth of the slab for the size in cubic meters. For example, if the slab is 10 m long by 5 m wide and 0.15 meters deep , the volume is 7.5 cubic meters.
Multiply the total by the density of concrete, which is rated as 2,400 kg per cubic meter for poured concrete and 3,000 kg for standard, rebar-reinforced concrete. For example, 7.5 x 2,400 = 18,000 kg and 7.5 x 3,000 = 22,500 kg.
Use a measuring tape to measure the length and width of the concrete slab in feet. Round to the nearest foot. Dig alongside the slab until you reach the bottom and measure the height of the slab in inches, rounding to the nearest inch. Record your measurements. If you need to replace only part of the slab, measure only the length, width, and height of the section.
Convert the slab height to yards by dividing it by 36.
Calculate the area of the slab by multiplying the length by the width. Then multiply by 0.111 to calculate the area in square yards. Use the area when determining the amount of material (e.g., tile or paint) necessary to cover the surface.
Multiply the area in square yards by the slab height in yards to calculate the volume of the slab in cubic yards. The cubic yardage is necessary when determining the amount of concrete used to create all or part of the slab.
Hire a clay truck to come to your job site. They are similar to cement trucks, but they hold a mixture of sand and clay that will not erode much over time.
On the side of the slab that you want to lift, use a concrete bore saw to drill a hole through the concrete, approximately 1 3/4 inch in diameter. A bore saw makes a hole just like a drill, but leaves the cylinder of material in tact so you can put it back in when you're done. If the slab is long, you may want to bore two holes, one on either side of it. The process of boring the hole will create concrete cylinders that fit back into the hole. Set aside the concrete cylinders.
Lower the clay truck valve into the hole and begin injecting the clay slowly, being sure not to lift the concrete above the level you want. When in doubt, inject less clay because you can always raise it a bit more, but you will not be able to get it lower once you’ve injected too much.
Replace the cylinders into the concrete, and spread some wet concrete or concrete-patching product over it to close the seams.
Choose the proper concrete screw for your application. See the resources below for information on strength and capability of a sampling of fasteners.
Since bottom plates are usually specified as pressure-treated wood, choose a fastener that is compatible with the wood composition.
Put on your safety glasses.
Using a masonry bit, drill a hole into the bottom plate and concrete 1/2 inch deeper than the concrete screw will reach. For 1/4-inch screws, use a 3/16-inch bit.
Drill all the holes needed for this piece of wood. Generally, concrete screws should be placed no closer than six inches apart, and not closer that four inches to the butt end of the bottom plate.
Clean the debris out of the hole.
Use the caulking gun and spread a bead of adhesive on the wood. Choose an adhesive that is compatible with concrete and the wood composition, and rated for outdoor use.
Place the wood on the concrete and line up the holes.
Place a concrete screw in each hole, and use the driver drill to slowly tighten the screw.
Depending upon the wood type, you may want to add a washer to distribute the load across the wood. Make sure that any washers are compatible with the wood type you are using.
Clean up any excess glue.
Laying Bricks on a Concrete Slab
Clean and inspect the concrete slab. Look for cracks and holes. Repair any damage to ensure that the slab is flat and even.
Measure the area of the slab in order to purchase the correct amount of bricks needed to cover the slab. Buy a few extra in case you damage some of the bricks.
Decide on the method you want to use to install your bricks. You may choose to use mortar in between the bricks to keep the patio more secure, or just lay the bricks on top of the slab without mortar.
Prepare the slab by covering it with mortar or compacted sand. You will need a 1/2 inch layer of coarse sand or prepared mortar.
Edge around the slab with strong plastic or metal. Do not allow the edging height to exceed the height of the bricks once the bricks are placed.
Lay the bricks on top of the sand or mortar as close together as possible. You may mortar in between the bricks if you choose. Otherwise, once the bricks are placed, put a layer of sand on top of and between the bricks then sweep away any excess sand.
Use a slab of wood at least 1/2 inch thick. You can make a shape out of any type wood. For a rustic look, cut a 1/2-inch slab from a tree trunk.
Use the belt sander with the 50-grit sand paper to rough sand the wood slab. Switch to the 80 grit to give a medium sand and use the 120 to give the wood slab a smooth finish.
Find and mark the center of the wood slab. This is where you will drill the hole for the clock mechanism to come through from the back. Use a drill with a drill bit the size of the center pole of the clock to make a hole on the mark.
Insert the clock mechanism from the back so that the pole is showing on the front side of the slab. Attach the square nut to secure the mechanism in place. Add the long and short hands to the center pole and fasten with the nut supplied in the kit.
Make marks on the wood slab where the numbers for the clock will go.
Use a rag to remove any dusk on the front side of the wood slab. Use the glue supplied in the clock kit to attach the numbers. Place a dab of glue on each number and place it where it should go.
Place the battery in the clock and set the hands.
From the downed tree, take a chainsaw or bow saw and cut several pieces of wood around 4 inches thick. Make them by cutting completely through the trunk of the tree. When finished you should have a roughly circular slab with the heart of the tree in the center surrounded by the concentric growth rings with a perimeter of bark.
Pass the slab through a planer, setting the height of the planer to allow all but the highest part of the slab to pass through. Repeat this step as needed until the slab is flat on one side.
Turn the slab over and repeat the process until both faces are flat.
Use a random orbit sander, and sand each face using progressively smoother grits starting at 80 grit and stopping at 220.
Apply a food-safe finish to the entire board, such as mineral oil or a specialty food finish. With mineral oil you will have to periodically reapply the finish. You'll also need to coat the top and sides and wait for them to dry before coating the bottom.
Use a hose on the highest setting to spray dirt and dust from the paving slabs.
Mix 2 tbsp. of liquid dish soap per gallon of hot water in a bucket.
Dip a mop in the solution. Mop the paving slabs.
Dip a cleaning brush in the solution. Rub the solution onto stains or embedded dirt that has not been removed by mopping.
Rinse all soap residue away from the paving slabs by spraying them with a hose.
Allow the paving slab to air dry.