Concrete DIY Tips
Every effort has been made to ensure accuracy and safety. We always recommend using a qualified concrete contractor
to ensure quality results. Chaney Enterprises cannot be held responsible for damages or injuries resulting from the use of the information in this document. Often times a contractor can be less expensive because of tools, experience and volume discounts in addition to the time savings and security of knowing it will get done right.
Most do it yourself projects are concrete slabs like a sidewalk, driveway, patio, etc. The guidance below is for that type of concrete work, but many of the principles apply to other concrete scenarios.
Tools and Materials you’ll Need
- Boards (or other suitable form materials)
- Garden Hose
- Finishing Trowel
- Brush or Broom (for dragging the surface)
- Cure and Seal
Preparation (Designing, Planning, Forming and Measuring)
The base under the concrete should be stabilized to ensure that it will not settle or move. Often time, concrete can be place directly on the non-frozen ground, but a compacted aggregate base (of stone or gravel) can help stabilize the ground.
Forms for the concrete are very important to get right. The first consideration for forms is exterior concrete slabs is that they will need to be set (pitched) at an angle to avoid water puddling on the concrete and drainage problems. A minimum angle of 1/8 inch per foot should allow water to flow off the slab and away from existing structures.
The more concrete within the forms, the more pressure that will be applied to them. You’ll want enough reinforcing stakes around your forms to protect the forms from bowing or blowing out entirely. A bowed form that bends from the weight of the concrete could leave you with undesired effects and might even have you come up short with the amount of concrete you order.
If any level of reinforcement is needed for major projects, it’s likely best to consult with a concrete contracting professional
. Too often, reinforcement is done incorrectly, in which case, it may be better to not have it at all. Proper jointing (see below) can address one of the reasons for reinforcement. If reinforcement is needed for load transfer between slabs or for significantly heavy loads, you will need to consult a professional
Placement and Finishing
Concrete is a perishable product, so speed of the pour is very important. This will protect the concrete and help you avoid additional charges for truck time. It’s best to have the truck be able to get close to your formwork and be able to discharge the concrete directly into the forms. If this is not possible, the concrete can be conveyed from one area to another with a variety of methods. Typically one wheelbarrow will not empty the truck fast enough. If using a wheelbarrow, be sure to have multiple wheelbarrows available and many willing and strong hands to keep the concrete flowing. A truck can hold about 10 cubic yards which weighs about 40,000 pounds. If you could take 400 pounds of concrete in each wheelbarrow load, that’s 100 trips back and forth to the truck!
Immediately prior to placing the concrete, the forms and base material should be wet down to insure that forms and base material do not absorb water from the concrete.
Now you are ready to place the concrete!
- Strikeoff or Screed – The concrete should be placed just over the top of the forms. You then level the concrete. Frequently a 2” x 4” board wider that the forms is dragged across the formwork in a sawing motion.
- Floating – This process will fill any rough voids left by the screeding action.
- Waiting for Bleed Water – Excess water will bleed out of the concrete. Never over-finish and trap the water below the surface, or finish the concrete while the water is on the surface. The water should evaporate from the surface.
- Jointing – All concrete cracks, so it’s important to let the concrete know where you want it to crack. This is the purpose of joints. An incorrectly placed joint will lead to unpredictable cracking. Joint depth should be at least ¼ the thickness of the slab, but not less than 1 inch. Joint spacing should be 24 to 36 times the thickness of the slab. All panels created from the joints should be nearly square. It’s better to have more joints than less joints, so for example, on a sidewalk that is 4 inches thick, you could joint every 8 feet, but if the sidewalk is 4 feet wide, that would not give you square panels, so you would want to add a joint every 4 feet.
- Edging – This prevents any chipping or damage at the edges of the slab.
- Final Floating and Troweling – This will level the surface.
- Brooming – Concrete can be finished quite smoothly (just think of the floors at a big box store). Typically on exterior slabs, you will want more traction so, a broom or brush finish can provide a nice, slip resistant surface.
Curing is one of the most important steps for concrete and one of the most neglected. Poor curing of a 4000-PSI mix can result is a 2000-PSI mix at the surface. We highly recommend a quality Cure and Seal compound
that will protect your concrete while it hardens and beyond. All exterior concrete should be sealed. Our Concrete Store
has many different types to fit your needs. If plastic is used instead, it should be placed without any wrinkles to avoid discoloring the concrete. Stapling the plastic to the firms can help with this.
You will need to provide a washout area for the truck after it is finished pouring the concrete. This should be a contained area that would not allow liquids to seep into surrounding areas. A wheelbarrow or other container is often the easiest to supply. Wash your tools and equipment thoroughly while the concrete is still wet. It’s easy and cheap to remove wet concrete and nearly impossible with dangerous and costly chemicals to remove it after it hardens.