A little preparation goes a long way in creating a durable, long-lasting base for your concrete. Check out these helpful tips to get started, and then give our experts a call at 360-699-1285 to schedule your concrete delivery and put over 20 years of experience to work for you and your project.
Thickness: 4" is generally a sufficient depth for parking areas, driveways, hot tub pads, and more. Additional depth may be beneficial for areas which receive higher traffic or which will hold heavier loads.
Base: Compacted earth may be entirely adequate as a base for residential concrete, however compacted rock is recommended for all applications of concrete placement. Base rock is usually 3/4" minus to 1" minus crushed.
Drainage or slope: The surface of the finished slab should slope at least 1/8 inch per foot away from structures for drainage. A slope of 1/4 inch per foot is ideal.
Excavation: Remove all organic matter and sludge, but don't excavate deeper than necessary. Place base rock of a minimum 2 inches.
Compaction: Soil on which concrete is to be placed must be compacted uniformly and evenly so the slab won't settle and vary in thickness. This also prevents future shifting and cracking of your concrete.
Concrete forms: You can form a 4" slab using 2" x 4's. Remove any loose materials from the edge to ensure full thickness around the perimeter of your pour. Stake securely.
Joint material: A barrier separating existing concrete from new concrete is necessary, and must extend to the bottom of the slab to ensure complete separation. Pre-molded material can be used, and should be placed against existing buildings, slabs, steps, and walls.
Strength: 3000 psi (5 sack mix) should suffice for most projects. The higher the concentration of cement (reflected in the sack mix or psi – pound per square inch), the greater the curing strength. Regardless of the mix, complete curing will take about 28 days.
Slump: A slump of about 5" is normally sufficient. A slump greater than 4" will extend the time needed for finishing, especially in cool weather. Higher slumps will also increase the potential for shrinkage and cracking.
Admixtures: Various products are available to accelerate or retard setting, reduce water content, and increase the plasticity of the concrete.
Calculation: Measure the length, width, and depth of the area that will be filled with concrete. A one inch difference in a 10' x 10' pad means approximately 21% more concrete, so make sure to measure carefully. Calculate the amount of concrete necessary.
Give us a call at 360-699-1285 to reserve a delivery time slot for the amount of concrete you need, allowing one to 2 days of notice during the winter months, and roughly a week's notice during the spring and summer months.
Filling Forms: Chute, wheel, or shovel the concrete to its final position, rather than dumping it in piles and then pushing or raking it to the desired location.
Leveling: Screed the concrete, which involves leveling the concrete by using a 2" x 4' in a sawing motion over the concrete. It is also recommended that the forms be gently tapped from the outside to eliminate any air pockets.
Immediately use wood or mag bull float to level out the high and low spots. At this time you can also edge the concrete with an edging tool, but do not do anything more to the surface until the water sheen disappears.
Timing: After the water sheen is gone (water is done bleeding to the top of your concrete), joint, edge, and texture your concrete as desired.
Final finish: A broom finish is the most common finish, particularly for driveways, sidewalks, and other exterior areas. A broom finish is also recommended for areas that may get wet and slippery. Machine floating and steel troweling are not recommended for exterior surfaces.
Joints: Control joints can be added with a hand tool or a saw, and must be cut at least 1/4 of the thickness of the slab. Joints must be continuous and straight – not staggered or offset. The spacing is 10' maximum, and square sections are preferable.
Control joints should be made after all finishing and curing applications are finished, and as soon as the concrete has sufficiently hardened to allow sawing without raveling.
Over-finishing: Over-finishing is the single best contributor to surface deterioration. Over-finishing pulls too much of the fine materials to the top, thus weakening the surface strength. Additionally, do not use a steel trowel on concrete that will be exposed to the weather.
Curing: Newly cured concrete should have a period of uninhibited exposure to the air before being sealed. A surface cure can be applied after final texturing is complete, and should not mar the concrete surface.
Curing is one of the most important steps in concrete construction. Effective curing is essential to good surface durability. Fresh concrete must be kept warm and moist until the water and cement hydrate (combine chemically). This is the process which hardens the concrete and gives it its strength.
Warm weather: The most common curing method is to spray or roll the slab surface after finishing to prevent premature drying. The rate of application should be consistent with the manufacturer's instructions. Water can be used in place of a cure if the surface can be kept wet for 3 days.
Cold weather: Newly poured concrete cannot freeze for at least a week. Only adequate insulation or heating will maintain proper curing temperatures during freezing weather.
Do not use a curing method that will allow the surface to dry in a short time. Concrete that dries too quickly is more likely to show surface cracking. Membrane curing is not sufficient, nor does the use of accelerants prevent concrete from freezing.
First winter: Do not use salt or other deicers during the first winter. Use sand instead to help improve traction. Even light applications of salt, or salt carried on cars, may cause severe scaling of newly placed concrete. Fertilizers are not an acceptable deicer at any time.
Drainage: Proper drainage will help avoid saturating the concrete.
Sealing: Sealing and curing are not the same. Water repellent coatings or sealers may inhibit water from getting into surface pores and help prevent damage from freezing, thawing, and salt. Newly cured concrete should have a period of air drying before being sealed.