Making and Curing Concrete Test Specimens in the Field

ASTMDesignation: C 31/C 31M

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.

Why do we make these specimens?

• Acceptance testing for specified strength • Checking adequacy of mixture proportions for specified

strength• Quality control.

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

Making specimen

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.)

Small tools, trowels

,.

Thermometer

Beam mold

mallet

Cylinder moldstrowels

Slump measuringapparatus

Air contentapparatus

Slump test

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

MOLDING• Place of molding should be; Flat, Rigid, Free from vibration, as

near as possible to storing place.• Consolidation; Rodding and vibration.

Rodding

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• Vibrator should be withdrawn slowly to avoid large air pockets• Tap the sides of mold with mallet 10 to 15 times to eliminate the air entrapped

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.

Curingstorage• 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.

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)

Curing continues…

final curing• Maintain water on the surface of specimen at all times.• Keep temperature around 23 °C• According to ASTM C 511Beams • 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

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.

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.

Thank youThat’s all.