The pressure method for air content determination can be used on concrete containing what type of aggregate?

The pressure method for determining air content in concrete is particularly effective with relatively dense aggregates. This method relies on the ability to create and manage stable air bubbles within the concrete mix, which can be accurately measured by observing changes in pressure. Dense aggregates typically provide a reliable matrix through which air can be entrained and maintained effectively, allowing for a more accurate assessment of air content without the risk of aggregate-related interferences.

In contrast, lightweight aggregates and high porosity aggregates may alter the air content readings due to their inherent physical properties, which can complicate the measurement process. Lightweight aggregates can absorb moisture and may trap air differently than denser materials, while high-porosity aggregates might not provide as consistent of an air distribution. Air-cooled blast furnace slag, while it has its own set of properties, can also behave differently, potentially leading to inaccurate air content determinations when using the pressure method. Thus, the suitability of the pressure method is maximized with relatively dense aggregates, making them the ideal choice for this specific testing approach.