What is the maximum aggregate size relative to flatwork?

What is the maximum aggregate size relative to flatwork?

• A. 1/3 size of flatwork
• B. 1/2 size of flatwork
• C. 1/4 size of flatwork
• D. 1/5 size of flatwork

Answer: (A)

In flatwork like slabs, the largest coarse aggregate you can use is limited by the slab’s thickness. The standard rule is that the maximum coarse aggregate size should not exceed about one-third of the slab thickness. This keeps the aggregate small enough to be fully surrounded by cement paste and properly compacted, which leads to a smooth finish and fewer voids or honeycombing. If the aggregate were too large relative to the depth, placing and consolidating the concrete becomes difficult, and the surface can be weak or rough. Smaller sizes, while workable, are usually unnecessary for typical mixes and add cost without giving a real benefit. So the one-third rule best balances workability, finish, and strength.

In flatwork like slabs, the largest coarse aggregate you can use is limited by the slab’s thickness. The standard rule is that the maximum coarse aggregate size should not exceed about one-third of the slab thickness. This keeps the aggregate small enough to be fully surrounded by cement paste and properly compacted, which leads to a smooth finish and fewer voids or honeycombing. If the aggregate were too large relative to the depth, placing and consolidating the concrete becomes difficult, and the surface can be weak or rough. Smaller sizes, while workable, are usually unnecessary for typical mixes and add cost without giving a real benefit. So the one-third rule best balances workability, finish, and strength.