The Constructor

Casting and Curing Concrete Specimens in Field Based on ASTM C31

Making Cylinder and Beam Specimens in Field Based on ASTM C31

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Casting and curing of concrete cylinder and beam specimens from representative samples of fresh concrete is crucial in building constructions.

This is because the results of the tests conducted on these specimens are employed for many significant purposes. For instance, acceptance of designated concrete strength, examine adequacy of mix proportions for strength, and quality control.

Moreover, the values of these specimen tests are also employed for specifying capacity of the structure to be put into service, check the adequacy of curing and protection of concrete structure, and form removal time requirements.

Lastly, the concrete used to make the molded specimens shall be sampled after all on-site adjustments have been made to the mixture proportions.


  1. Cylinder Molds
  2. Beam Molds
  3. Tamping Rod for which requirements are presented in Table 1.
  4. Vibrators
  5. Mallet
  6. Placement Tools
  7. Finishing Tools
  8. Slump Apparatus
  9. Air Content Apparatus
  10. Temperature Measuring Devices

Table 1 Tamping Rod Diameter Requirements

Diameter of Cylinder or Width of Beam, mmDiameter or Rod, mm
<15010 ± 2
$15016 ± 2
Fig. 1: Cylinder and Beam Molds

Testing Requirements

Table 2 Minimum Cross-Sectional Dimension of Beams

Nominal Maximum Aggregate Size, mmMinimum Cross-Sectional Dimension, mm
Equal or smaller than 25100 by 100
Greater than 25 but smaller than 50150 by 150


Measure and record the slump of each batch ofconcrete

Air Content

Determine and record the air content

Molding Specimens

Fig. 2: Casting Cylinder and Beam Specimens in Field

Table 3 Method of Consolidation Requirements

Slump, mmMethod of Consolidation
Equal or greater than 25rodding or vibration
Smaller than 25vibration

Table 4 Molding Requirements by Rodding

Specimen Type and SizeNumber of Layers of Approximately Equal DepthNumber of Roddings per Layer
Diameter of Cylinder specimens, mm  
Width of beam specimens  
100 to 2002One rodding for for each 14 cm^2 of the top surface area of the beam.  
Greater than 2003 or more equal depths, each not to exceed 150 mmOne rodding for for each 14 cm^2 of the top surface area of the beam.  

Table 5 Molding Requirements by Vibration

Specimen Type and SizeNumber of LayersNumber of vibrator insertions per LayerApproximate Depth of Layer, mm
Diameter of Cylinder specimens, mm   
10021one-half depth of specimen
15022one-half depth of specimen
22524one-half depth of specimen
Width of beam specimens   
100 to 2001Use rodding or vibrationdepth of specimen
Greater than 2002 or more  Use rodding or vibration200 as near as practicable

Finishing and Marking

Initial Curing

  1. After finishing, specimens should be stored for up to 48hours in a temperature range of 16 to 27°C or 20 and 26°C for specified concrete strength of 40MPa or higher,
  2. Specimens should be protected from direct sun light, radiant heating devices to prevent the loss of moisture. Heating and cooling machineries may be used for this purpose.

Final Curing

Standard Curing

Fig. 3:Curing of Concrete Specimens

Field Curing

Fig. 5: Field Curing of Concrete Specimens


The following data should be provided to the lab where the specimens are tested:

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