Factors Affecting Creep

In concrete mixes, the hardened cement paste primarily contributes to creep, while the aggregates in the mix restrain creep.

Aggregates with a high modulus of elasticity, being stiffer, reduce creep. Hence, the greater their volume in the concrete, the lower the creep.

Creep linearly increases with the stress applied within design limits. Beyond the design limits, creep increases non-linearly with the applied stress.

Consequently, for concrete mixes with similar cement paste content, lower water-to-cement ratio mixes exhibit higher strength and less creep.

Moreover, as the age of load application increases, the creep decreases as the concrete gains strength with time. 

Curing concrete at elevated temperatures before loading enhances its strength, further reducing creep.

Early-loaded members with high-early-strength cement have less creep than those with ordinary Portland cement.

Admixtures in concrete that increase the volume of fine pores holding moisture lead to increased creep.

Lastly, the concrete member's size and the relative humidity of the surrounding air affect creep. The higher the relative humidity, the lower the creep, and larger members exhibit less creep at constant relative humidity.