Ghamelas are used in batching of concrete with different sizes and shapes. Sometime it can results in large errors and variation in batching of concrete. Following are some disadvantages of using ghamelas while batching of concrete.
01. Size and shape Different (Dia/Depth)
Different sizes of ghamela are used in batching of concrete on site. Sometimes labours use big diameter of ghamela for batching of aggregates and gamela of smaller diameter for batching of cement and therefore quantity of aggregate may get increase and quantity of cement may get reduced in batching of concrete. Therefore volume of concrete ingredients may differ from the actual mix design proportion and if it less than designed mix proportion, it can affect the desired strength of concrete.
Sometimes labours use damaged ghamelas having irregular shapes. Therefore volume of concrete ingredients differs from the actual mix design proportion.
Also Read: What is Volumetric Batching of Concrete?
02. Ingredients filling-varying volume
When concrete ingredients are filled in ghamelas, they are not filled exactly to the rim of ghamela. Sometimes it may be filled below the rim of ghamela or above the rim of ghamela and may produce heap in ghamela. Therefore volume of concrete ingredients is less or more from the actual mix design proportion and it affects the desired strength of concrete.
03. Counting of numbers
Most of the time on small site or works there are no Engineer-in-charge or supervisor on site while batching of concrete is carried out. Labours working on site are unskilled and sometimes they don’t count ghamelas suggested by Engineer-in-charge or supervisor. It may be that sometimes nobody watches. There may be less or more numbers of ghamelas batched in mixer and proportion of concrete ingredients may get changed, affect the desired strength.
Concrete batching with ghamela to be proven error prone method and concrete is not achieved with uniform quality. Sometimes concrete may not be workable and cohesive and there may be chances of voids in concrete that affects the strength and durability of concrete structure. It may certainly change the properties of fresh as well as hardened concrete.
Use of ghamelas for batching is very crude not at all recommended. Moreover this is highly unscientific method. It must be stopped immediately or should not be permitted under any circumstances.