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What are autographic batch records?

The term ‘autographic’ is taken to mean records produced by the plant equipment or system as opposed to records hand produced by plant personnel. This automatic information comes from computerised systems with input from load cells on materials weigh scales, flow meters on water and admixture dispensers, moisture contents from meters fitted to the aggregate bins and concrete mixer etc.

While batch records come in many formats, the information provided should comprise the following:

• information related to the identification of the load
• size of the load in cubic metres
• theoretical quantities of constituents to be batched, (which are the mix proportions for a cubic metre multiplied by the load size)
• moisture contents of the aggregates
• required quantities of constituents to be batched, (which are the theoretical quantities after adjustment for the moisture content of the aggregates)
• the actual quantities batched
• the difference between the required quantity and the actual quantity. (This information may be used to confirm that the batching tolerances have been achieved. It is rare that the exact required quantities are batched and this is why standards permit small batching tolerances)
• the effective or total w/c ratio for the load.

However, many autographic records do not provide enough information for back-analysis if so desired.

Note: w/c (water/cement) ratio can also be written as w/b (water/binder) ratio, the binder being the sum of the various cementitious components.

Acknowledgement: The Concrete Society

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Control and conformity of water to binder ratio in fresh concrete