This document provides guidance on making and curing concrete test specimens in the field according to ASTM C 31/C 31M. It describes why test specimens are made, including for acceptance testing of specified strength, checking mixture proportions, and quality control. The key steps covered are: making specimens using molds, consolidating the concrete through rodding and vibration, finishing, initial curing within 48 hours at 16-27°C, final curing by maintaining moisture on the surface at 23°C, and transporting specimens only after 8 hours without jarring or temperature extremes to prevent damage.

1. Making and Curing
ConcreteTest Specimens
in the Field
ASTM
Designation: C 31/C 31M

2. PRESENTATION OUTCOMES
• Why do we make these specimens?
• To know purpose of test conducted.
• To enable you to Make, cure and transport concrete test specimens under
field conditions.

3. Why do we make these specimens?
• Acceptance testing for specified strength
• Checking adequacy of mixture proportions for specified strength
• Quality control.

4. Purposes the tests are conducted for.
• Determination of whether a structure is capable of being put in service
• Comparison with test results of standard cured specimens
• Adequacy of curing and protection

5. Making specimen

6. Apparatus:
• Cylinder mold (C 470)
• Beam mold (c 470)
• Tamping rod
• Internal vibrator (150 Hz)
• Mallet (o.6 kg)
• Sampling receptacle
• Slump apparatus (C 143)
• Air content apparatus (C 173)
• Temperature measuring device (C 1064)
• Small tools (shovels, trowels etc.)

7. Small tools, trowels
,.
Thermometer
Beam mold
mallet
Cylinder molds
trowels
Slump measuring
apparatus
Air content
apparatus

8. Slump test
• To check the adequacy of our concrete
• To decide the method of consolidation
• According to (ASTM C 143)

9. MOLDING
• Place of molding should be; Flat, Rigid, Free from vibration, as near as
possible to storing place.
• Consolidation; Rodding and vibration.

10. Rodding

11. Vibration
• Vibrator should be withdrawn slowly to avoid large air pockets
• Tap the sides of mold with mallet 10 to 15 times to eliminate the air entrapped

12. Finishing
• Strike off extra concrete from the surface with least manipulation
• Level the surface with suitable tool like trowel or float.
• No projection or depression greater than 3.3 mm be tolerated.
• If desired, cap the surface of freshly made cylinder with a thin layer of
Portland cement paste.

13. Curing
storage
• Move to a place where initial curing is possible immediately after finishing.
• Storing surface shall be leveled within 1⁄4 in. per feet [20 mm per m].
• Support the bottom of mold with flat surface during movement.
• Refinish the surface immediately if marred.

14. Curing continues…
initial curing
• Initial curing temperature must be 16 to 27 °C during 1st 48 hours.
• Prevent moisture loss.
• Specific temperature(20-26 °C) needed for specific strength(40 MPa)

15. Curing continues…
final curing
• Maintain water on the surface of specimen at all times.
• Keep temperature around 23 °C
• According to ASTM C 511
Beams
• Beams are to be cured the same as cylinders except that they shall be stored in
water saturated with calcium hydroxide at [23 °C] at least 20 h prior to testing

16. Transportation
• Specimens shall not be transported until at least 8 h after final set.
• Prevent jarring damage
• Prevent freezing and over heating by proper insulation.
• Prevent moisture loss by wrapping specimen with plastic, burlaps etc.
• Transportation time shall not exceed 4 hours.

17. Report
Report the following information to the laboratory that will test the specimens:
• Identification number.
• Location of concrete represented by the samples.
• Date, time and name of individual molding specimens.
• Slump, air content, and concrete temperature, test results.
• Curing method.

18. Thank you
That’s all.