[Manish Jain]

2.0 INFLUENCE OF BATCIDNG AND MIXING PROCESSED ON FRESH CONCRETE

2.1 The factors which influence the quality of fresh concrete are as follows :
2.1.1 CONSISTANT QUALITY OF RAW MATERIALS
Consistent quality of raw materials is very essential. Batching and mixing is more consistent if the raw materials with consistent specific gravity, fineness,
grain size, strength and other properties are used. Variation in grading and fineness can; create variations in concrete quality as the water demand or
workability for the same proportions may increase or decrease. 

2.1.2 ACCURACY. OF BATCHING (VOLUMETRIC I WEIGHMENT)
Batching accuracy is also important. It is preferred to do weigh hatching and not volumetric hatching of cement and aggregates. However, if accurate weigh
hatchers are :not available it is preferable to do proper volumetric hatching. Bulkage correction for natural moist sand is necessary in case of volumetric
hatching. ·
2.1.3 ADEQUACY OF MIXING (MANUAL/MECHANICAL)
Mixing is generally practiced manually in case of mortar and at times even for concrete. Manual mixing is not recommended until
and unless the work is carried out by trained skilled worker in a systematic manner. Machine mixing is faster and more efficient than manual mixing.
It is often observed that mixers Figure 1 : Inadequately designed mixer causes mix to segregate. 
used in our country are not properly
designed to cater to adequate mixing of concrete materials . Care should be taken that mixers available on site are capable of mixing the concrete ingredients.

2.1.4 MIXING TIME
It is necessary to ensure that adequate time is given for proper mixing of concrete ingredients. However; mixing time may greatly depend on the workability of concrete mix, type of mixer and it's size or capacity.

2.1.5 BATCHING AND MIXING EQUIPMENTS AND METHODS
There are various types of hatching and mixing equipment's and methods that is to say from manual to most sophisticated computerized hatching and mixing. 
Mechanization improves quality of batching and mixing, its speed and thereby can most often result in economy. 
Manual batching and mixing is more prone to errors and slower in speed than mechanical arrangement. Volumetric batching if done with proper boxes (farmas) and filled up to brim and levelled is quite accurate for batching aggregates.

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 batching and mixing of mortar and concrete ingredients-fd.pdf