Which method of production sampling requires that production be shut down?

The method of production sampling that requires the production to be shut down is known as on-belt sampling. This technique involves taking samples directly from the production conveyor where aggregate materials are being transported. Because this method necessitates a precise and uncontaminated sample that accurately represents the material being produced at a specific moment, it's essential to halt production during the sampling process. This prevents any ongoing movement or mixing of materials that could compromise the integrity of the sample.

In contrast, the other methods listed do not require a shutdown. For example, off-belt sampling allows for samples to be taken from the finished product without interrupting the production line. Spot checks are conducted at various intervals during a production run, typically when production is ongoing. Continuous sampling involves taking samples over a longer period without stopping the production, allowing for a representative analysis without the need to halt operations.