The minimum cementitious material that is required for concrete bridging deck is ______________lbs/cu yd.

• A. 675
• B. 700
• C. 650
• D. 600

Answer: (A)

Bridge deck mixes are required to have a minimum amount of cementitious material to ensure durability, proper paste content, and resistance to freeze–thaw and deicing salts. Cementitious material includes cement plus any supplementary cementitious materials (such as fly ash, slag, or silica fume) counted toward the total.

The standard minimum is 675 pounds per cubic yard. This level provides enough paste to coat aggregates, achieve the necessary density and bonding, and work well with air-entraining admixtures to improve durability under harsh conditions. Values lower than this would create a leaner mix with higher permeability and greater risk of cracking, scaling, and salt damage, while the total can be met by combining cement with SCMs as long as the overall content reaches 675 lb/yd^3.