Basic Concrete Finishing Knowledge for Tacoma, Washington

   Planning and Preparation

  Before you begin your project, it is important to properly  plan and prepare. Proper planning will save time in the end, and helps  to assure your satisfaction with the product. If you are unsure of how  much concrete you need or if the area is suitable for concrete,  give Cascade Mobile Mix Concrete & Line Pumping a call today at  253-847-9119. Our staff is experienced in all types of concrete pouring  situations and will answer all of your questions. 

Thickness

For common household projects - driveways, walkways, and patios – 4  inches thick should do the trick. Thicker concrete (i.e. 6" is  recommended for heavy-duty use or heavy vehicles) It is recommended to  use a ¾ minus crushed gravel compacted base. You can get a compactor  from a rental equipment store. Drainage industry standard calls for a  slope of ¼ inch per foot away from structures. Some projects may be able  to use ⅛ inch slope. 

Excavation

While taking care to only dig as deep as necessary (keeping an eye out  for power lines; if you are unsure where lines are, call your utilities  for a locator), ensure you remove tree roots, leaves, wood and any other  organic matter in the desired area. 

Isolation

Install expansion joint material anywhere concrete will come into  contact with existing slabs, steps or buildings. The expansion joint  should reach the bottom of the slab; this ensures the new slab will be  separated from existing structures.

Now that you have your planning down, we suggest you review our Concrete Calculator to determine your exact needs. 

Specifications

Specifying the correct mix for your job can be the difference between  long-term satisfaction and disaster. Concrete specifications consist of  strength (PSI), slump (thickness) and chemical additives. 

Strength

Concrete Exposed to freezing and thawing temperatures should have a  compression strength of 3000 psi and have at least 5% entrained air (+/-  1.5%). Air entrainment allows for the expanded water when frozen to  travel into the air voids created by the air additive. Without the air,  concrete is at risk for cracking. 

Slump

For our environment, we recommend a slump of 4 inches (+/- 1"). Note: a  slump greater than 4" may prolong the time you have to wait before  finishing, particularly in cool weather. It will also increase the  tendency for shrinkage cracking. 

Compaction

Will ensure your slab won't settle or vary in thickness, make sure to compact the soil/gravel base in the desired area. 

Forming

Take care to stake your forms securely to the ground, while paying close  attention to the slope (for proper drainage). 2x4s are perfectly  adequate for use as forms; though make sure you have the desired  thickness (usually 4") available at the edges. 


Chemical Additives

In addition to air entraining admixtures, chemical additives may be used  to accelerate or retard setting, reduce water or plasticize the  concrete. 

Cascade Mobile Mix Concrete & Line Pumping

Cascade Mobile Mix Concrete & Line Pumping's concrete is a  high-quality concrete and we run a plasticizer in our concrete unless  requested not too. 

Placing and Finishing

 

Placing
Concrete  delivery should be closely coordinated with placing and finishing  operations. Concrete should not be poured faster than it can be worked -  spreading, consolidating, bull floating. Instead, concrete should be  poured continuously as near as possible to its final position. You  should never dump concrete into separate piles and work together.

Consolidation
Placing  concrete in forms and then consolidating is popular for some types of  construction. The consolidation process uses vibration and gravity to  compact fresh concrete within the forms and around embedded items and  reinforcement. This process eliminates unwanted pockets of trapped air,  honeycomb, and stone while maintaining significant amounts of entrained  air. The vibration temporarily suspends the natural friction between the  aggregate particles, causing the concrete to behave as a liquid.  Internal friction resumes as the vibration is stopped.

Finishing
Visible  concrete - slabs used for driveways, patios, etc. - will often need  finishing. You can finish your concrete in many ways, including color  tinting and texturing. Patterned-stamped finishes are very popular on  projects of all sizes. Some surfaces may require just strike off and  screeding to proper contour and elevation. Others may be better off with  a broomed, troweled or floated finish. Strike off and screeding is the  process of cutting off excess concrete to bring the top surface of the  slab to proper grade. A straight edge is moved across the concrete with a  sawing motion and progresses forward a short distance with each  movement.
Bull floating  eliminates high and low spots and embeds large aggregate particles  immediately after strike off. This looks like a long-handled straight  edge pulled across the concrete. Jointing is required to eliminate  unsightly random cracks. Contraction joints are made with a hand groover  or by inserting strips of plastic, wood, metal, or preformed joint  material into the unhardened concrete. Saw cut joints can be made after  the concrete is sufficiently hard or strong enough to prevent raveling.  After the concrete has been jointed, it should be floated with a wood or  metal hand float or with a finishing machine using float blades. This  embeds aggregate particles just beneath the surface; removes slight  imperfections, humps, and voids; and compacts the mortar at the surface  in preparation for additional finishing operations. Where a smooth,  hard, dense surface is desired, floating should be followed by steel  troweling. Troweling should not be done on a surface that has not been  floated; troweling after only bull floating is not an adequate finish  procedure. A slip-resistant surface can be produced by brooming before  the concrete has thoroughly hardened, but it should be sufficiently hard  to retain the scoring impression.

Curing and Drying

Curing
Curing is  one of the most important steps in concrete construction, because proper  curing greatly increases concrete strength and durability. Concrete  hardens as a result of hydration: the chemical reaction between cement  and water. However, hydration occurs only if water is available and if  the concrete's temperature stays within a suitable range. During the  curing period, from five to seven days after placement for conventional  concrete – the concrete surface needs to be kept moist to permit the  hydration process. The most common method of curing (and one of the  simplest) is to utilize a liquid membrane, which is sprayed or rolled on  the surface of a slab after finishing to prevent premature drying of  the surface. Water may be used when you are able to ensure constant  wetting for at least 3 days.
 

Curing in Extreme Weather
Temperature  extremes make it difficult to properly cure concrete. On hot days, too  much water is lost by evaporation from newly placed concrete. If the  temperature drops too close to freezing, hydration slows to nearly a  standstill. Under these conditions, concrete ceases to gain strength and  other desirable properties. In general, the temperature of new concrete  should not be allowed to fall below 50°F during the curing period.  Membrane curing does not keep the concrete warm enough in freezing  temperature, nor does calcium chloride accelerator prevent concrete from  freezing. Only adequate insulation or heating will maintain proper  curing temperatures during freezing weather.

Curing Shortcuts to Avoid Compaction
Avoid  any curing method that lets the surface dry in a short time. Quick  drying stops the hardening process, thus making a weak surface that is  likely to scale.
 

Drying
After curing, newly  placed outdoor concrete needs time to dry in warm air. For best results,  plan to place your concrete early enough in the season so that it has  one month of temperatures above 40°F for curing and still another month  for drying out before hard freezes are expected.



 

Concrete Maintenance Tips

 

Sealing
Water-repellent coatings or  sealers can help prevent damage from freeze/thaw cycles and salting.  They deter water from getting into the surface pores. Newly cured  concrete should have a period of air-drying before being sealed.
 

First Winter
Do  not use salt or other deicers during the first winter. Use sand instead  to 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.
Saturation

Proper drainage should be maintained to avoid saturation of concrete.

Why Choose Us?

    

  • Deliveries 24/7 from 3 locations by appointments
  • Dependable delivery timelines
  • Work with homeowners and contractors
  • Residential, commercial, and industrial pouring available
  • Very knowledgeable and trained staff and crew

  

  • From small to large jobs, we will assist you
  • Locally and family owned company, since 1979
  • Serving all of Western Washington state
  • Our line pump truck can reach most areas

We deliver concrete  to Pierce, South King, Lewis and Thurston Counties. Upon request we can  go anywhere and are capable of pouring in remote wilderness areas, on  barges in our waterways, whatever you need is, we will try our best to  accommodate you. 

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Cascade Mobile Mix Concrete

253-847-9119

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