Weigh Batching vs Volume Batching

Weigh Batching vs Volume Batching Sr.  No.

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Weigh Batching

Volumetric Batching

The concrete ingredients are batched/  proportioned based on weight. weight. Batching by mass mass is achieved by using weigh batching machine/ plant.

The concrete ingredients are batched / proportioned  based on volume. Batching by volume achieved by using a constructed gauge boxes (Farmas) for proportioning the materials according to various mix proportions and based on the quantity of material needed per batch.

In small works gamellas works  gamellas are  are also used for  batching. But it is not recommended recommended for batching of concrete. 03.

 Nominal mix is batched by mass using regularly maintained and well-calibrated equipment, therefore high degree of uniformity in proportion of the fresh and hardened state concrete can be achieved.

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Materials batched by mass are exact in measurement taking cognisance of the differences in the material properties. Water for mixing is weighed out precisely as a function of the weight of cement used for each mix proportion. Hence uniform water-cement water-cem ent ratio can be maintained, which plays an important role in achieving strength of concrete. Each batch is weighed which makes it easy to detect overruns or incorrect dosages. The slump of concrete batched by mass is higher than batched by volume for same mix proportion and water cement ratios. i.e. slump varies from medium to very high slump. For same mix proportion, the compressive strength of concrete batched by mass is higher than that batched by volume at all w/c ratios and for curing ages 7 to 28 days. Admixtures are pre-weighed then held in the hoppers ensuring rapid discharge with no impact on batch cycle Admixtures can be dosed at any stage of  batching and in multiple dumps- thereby achieving optimal performance. Concrete is of uniform and consistent quality.

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More precise method.  Need skilled labours Operation difficult. Speed of construction is high. Maintenance cost is high. This method is expensive.

When batching by volume is used, possible sources of error could lead to variation in the amount of aggregate in a specific volume and errors in measured volume. These errors often lead to variations in the fresh and hardened properties of concrete as against specified characteristics properties. Variations in quantity are very much likely for materials. ultimately affect strength of concrete. The volume of water required for mixing is not often specified. Sometime extra water is added to make concrete workable.

This makes concrete non uniform and reduce the strength. Difficult to detect overruns or incorrect dosages. Slump varies from low to high.

For same mix proportion, the compressive strength of concrete batched by volume is lower than that batched  by mass at all w/c ratios ratios and for curing ages 7 to 28 days. Admixtures are batched directly into correct mix, which could slow batching cycle. Admixtures are difficult to batch at certain stages of the batching sequence. The quality of concrete may differ because of bulkage of fine aggregates (Sand) and therefore concrete is not uniform and consistent.. Less precise method. No need to required required skilled labours. Easy to operate. Speed of construction is slower than weigh batching. Maintenance cost is practically nill. This method is cheaper and economical.