Making and Curing of Concrete Cubes (BS EN-12390 Part 2)

 

Making and Curing Concrete Cubes

 (BS EN-12390 Part 2)




Introduction

This standard specifies a method for making and curing test specimens for strength test


Apparatus

Cubes Molds = L 6 x W 6 x H6

Internal Vibrator = minimum frequency 120 Hz, diameter not exceeding one-quarter

Vibration Table = minimum frequency 40 Hz

Compacting Bar = having a square cross-section of approximately 25 by 25mm and a length of approximately 380mm

Mallet


Procedure

Remix the sample before filling the cube molds

Before filling the concrete, covered the mold's inner surface with a thin film of non-reactive release material 

Specimen compacted minimum of two layers, but no layer more than 100 mm in thickness

Mechanical vibration or hand compaction


Mechanical Vibration

Vibrate the concrete until the all entrapped air remove from the concrete and the depression left from the surface of a concrete

over-vibration is the cause of segregation

Hand Compaction

The first layer,
distribute the strokes in uniform manners over the cross-section of the mold

The compaction bar or rod does not touch the bottom of a mold forcibly when compacting the first layer

Subject the concrete to at least 25 strokes per layer or until the remove entrapped air from concrete

Tap the mold outer surface with the mallet until the depression left from the surface of the concrete

The Second Layer,
The compacted bar or rod does not penetrate the previous layer significantly

Subject the concrete to at least 25 strokes per layer or until the remove entrapped air from concrete

Tap the mold outer surface with the mallet until the depression left from the surface of the concrete

Surface Leveling

Remove all excess concrete above the mold with a trowel or other tools 

The surface should be level sawing motion smoothly without depression

Curing Specimens

Leave the specimens molds at least 16 hrs but not more than 3 days 

Protect the specimens molds from vibration and dehydration at a temperature of 20 + 5°C or hot climates of 25 + 5°C 

after the removal of the specimen from the mold cure the specimen till before testing

The water temperature of the curing tank is 20 + 2°C and relative humidity is > 95%

Transportation of Specimens

Avoid the loss of moisture and deviation from the required temperature at all stages of the transportation

 Covered the hardened specimens from wet sand, wet sawdust, wet cloth, or plastic bags








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