Effect factors of drying shrinkage of steam-cured concretes incorporating fly ash

Steam-cured concretes are used widely in the precast industry to speed up production. The drying shrinkage of steam-cured concretes is closely related with its durability. To reduce the drying shrinkage of steam-cured concretes, this paper investigated the values of drying shrinkage of steam-cured concretes with various mixes by dial indicators fixed in a frame and the effect of mix parameters on the drying shrinkage of steam-cured concretes. Test results indicate that with the increase in fly ash, drying shrinkage is not a monotonous change in value, and the lowest value of drying shrinkage is obtained for the mix with 30% fly ash. With water-cement ratio decrease to below 0.28, autogenous shrinkage create due to self-desiccation and then shrinkage increase; When the sand ratio increase from 0.33 to 0.36, the drying shrinkage of steam-cured concretes decrease 27%.