What is the accuracy requirement for balances used with coarse aggregate or mixtures as stated in C136?

The accuracy requirement for balances used with coarse aggregate or mixtures, as specified in C136, indicates that the balance must be capable of measuring to the nearest 0.5 grams or the nearest 0.1%. This level of accuracy is critical because it ensures the precise measurement of aggregates, which directly affects the quality and consistency of the concrete mix. Coarse aggregates, which can vary significantly in size and weight, require careful handling and weighing to maintain the desired properties in construction applications.

This requirement allows for adequate precision while also accommodating the larger masses typically associated with coarse aggregates, acknowledging the potential for larger variation in weight compared to finer materials. Using a balance that measures to this standard helps ensure that mixtures are properly proportioned, which is crucial for achieving the desired strength and durability in the finished product.

Other choices like being readable to the nearest 1 gram or 0.1 gram may not provide sufficient accuracy for the intended applications, while a balance that is only readable to the nearest whole number would lack the necessary precision for consistent and reliable measurements of aggregate materials.