Compaction Of Concrete And Methods Of Compaction Of Concrete


COMPACTION

Compaction is  one of the process of concreting. Compaction is the process of exhaust of air voids from the concrete. Because the presence of air voids make honeycomb in concrete. It will total make the concrete strength less. 1 % of air voids reduce the concrete strength approximately 6 %.

 Compaction of concrete can be done either by manually of mechanically. Manual compaction is the hand compaction without use any machines just it is done by using tamping rods. 

 Mechanical compaction in term machines is used to make compaction they are vibrators. 

 The compaction process is explained below deeply.

METHODS OF COMPACTION OF CONCRETE

 They are many factors consider for choosing compaction method such as reinforcement quantity and spacing, depth of concrete structure, nature of availability of machines, location of concrete structure, concrete paste consistency ,form work difficulty. Methods of compaction are below.

 HAND COMPACTION METHOD

 Hand compaction is done by three methods Roding, ramming and tamping.

 In Roding method a 2 m long and 16 mm dia rod is used. The edges of the rod should be sharp. Thickness of concrete is 150 mm to 120 mm this method is followed

 Compaction process is done throughout the concrete area.  Compaction should be proceeding until it is get fully compacted.

 Another method is tamping. In tamping method 10 cm x 10 cm size cross beam is used to compact the concrete. Compaction and concrete surface level is maintained uniformly. it is used for road pavement flooring concrete and roof concrete works.

MECHANICAL COMPACTION

 In mechanical compaction method vibration technique is mostly used. Vibration causes temporary liquefaction so the stored air between aggregates is removed immediately. Various types of vibrators are used. They are following below.

INTERNAL VIBRATORS OR NEEDLE VIBRATORS


 Internal vibrators or needle vibrators are used for compaction of slabs , beams, columns . Vibrator needle head is having diameter of 2 cm to 18 cm and the shape of the head is cylindrical. Internal vibration is maintained accurately because over vibration time make the concrete segregation. Vibrator needle should be submerged into concrete element.

EXTERNAL VIBRATORS


 External vibration method is used where internal vibration can’t be used. Because thin concrete layer or heavy reinforcement structure. External vibrators consume more power compared to internal vibrator, also it give less effect. Form work required extra strong for external vibration method.

TABLE VIBRATORS 


 This method is used only laboratories. Concrete is placed above table and the vibrator is fixed below table.

SURFACE VIBRATOR


 Surface vibrators are fixed a long board, vibrators are activated then the vibration is transferred into concrete surface. This is not effective method. Also this method is normally used where the depth of concrete is 10 to 15 cm like roof slab and floor slab.

RESULT OF IMPROPER VIBRATIONS OF CONCRETE

 Concrete structure required adequate compaction otherwise the following problems may be arise.

HONEY COMB


 In adequate compaction or without compaction make honey comb in concrete structure. Honey comb is nothing but air voids between it is after settlement of concrete it is formed pit. It is totally affect concrete strength.

ALSO READ
CRACKS IN BUILDING AND CONCRETE
PRE- STRESSED CONCRETE AND TYPES
PROCESS IN MANUFACTURING OF CONCRETE

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