Abstract: Effects of microdosage phosphate (≤0.05%) on the compressive strength of steam-curing concrete were investigated, the effects of the different dosage of CaCl2 and Na2SO4 on the compressive strength of steam-curing concrete were compared with mircodosage phosphate, and the microstructure of samples with different phosphate was also analyzed.The results show that the compressive strength of steam-curing concrete increases and then decreases with the dosage of phosphate increasing.In the dosage of 0.01%, the early compressive strength increases 14.7%, 28 d strength increased 15.3%, in the dosage of 0.05%, it is harmful for the strength.The microdosage CaCl2 and Na2SO4 have no influence on the compressive strength of steam curing concrete.Phosphate can promote the hydration of cementand make the cement hydration crystal growth regularly and well-distributed in the dosage of 0.01%, which is benefit to the development of the strength;In the dosage of 0.05%, phosphate have an ability to delay cement hydration, it is most detrimental to the development of steam-curing concrete strength.

Key words: phosphate;microdosage;steam-curing concrete;strength