What is the maximum size of aggregate required for an unreinforced 4" wall?

The maximum size of aggregate used in concrete for unreinforced walls, specifically for a 4-inch wall, is indeed 3/4 inch. The reasoning behind this is primarily related to achieving the proper consistency and strength of the concrete mix.

When constructing a concrete structure, the size of the aggregate plays a crucial role in the mix's workability, bonding, and overall performance. For a wall that is only 4 inches thick, a smaller aggregate size such as 3/4 inch ensures that the concrete can fill gaps efficiently and maintain a dense, solid structure without leaving voids that could compromise its strength.

Using larger aggregate sizes, such as 1 inch or 1 1/2 inches, could lead to difficulties in achieving proper consolidation within such a narrow wall, potentially resulting in a weaker structure due to poor concrete compaction. Thus, the choice of 3/4 inch aggregate is ideal for balancing structural integrity and workability in thinner concrete applications.