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Imperial On-Site Concrete calculator.

Use this calculator to determine how much sand, aggregate (gravel) and cement is required for mixing on site a given area of concrete (1:2:4 ratio).

The calculations will be completed when you leave the last input field. See below for help on concrete.


Dimensions  
Feet Inches
Length
Width
Depth
Cubic Yards
Cubic Feet     

Results
   40lb bags    60lb bags    80lb bags
Cement lb    
Sharp Sand lb    
Gravel Kg    
Water gallons    
OR
80lb concrete bags    
60lb concrete bags    
40lb concrete bags

These figures are dependant on many factors such as use of concrete, thickness of concrete, location, price of materials etc.


Desirable properties in a concrete mix

  • Ensure the concrete mix is workable which allows correct placement and consolidation
  • Ensure the optimum desired quality of the hardened concrete is met which improves resistance to freezing and thawing, water tightness (low permeability) , wear resistance, and strength.
  • The quality of the concrete is dependant mainly on the water to cement ratio, so water requirements should be minimised to reduce the cement requirement thereby reducing the overall cost.
  • The mix should be a stiff as possible.
  • Use the largest aggregate practicable.
  • Use the optimum ratio of fines to coarse aggregate.
  • A low water to cement ratio is the number one issue that affects concrete quality. Do not add too much water.

Components in concrete

  • Portland Cement - the aggregate and sand is coated by a paste formed from the cement and water. This paste then hardens and binds the fines (sand) and aggregate together
  • Water - this is needed to chemically react with the cement and to make the concrete workable.
  • Aggregate - The fines are sand and gravel or crushed stone is the coarse aggregate (10, 20 & 40mm) in most mixes.

Admixtures in Concrete

  • Accelerators - added to the concrete to reduce overall setting times and gain early strength. Calcium chloride is the lower cost accelerator, however a non-chloride accelerator should be specified if reinforcing has been used, to prevent corrosion of the steel.
  • Retarder - used in hot weather to delay setting. Also used for difficult jobs and specialist finishes. May also act as a water reducer
  • Fly Ash - improves workability, easier to finish and reduces the cement content.
  • Air Entrainment - improves the workability of the concrete as well as the durability.





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