Recently, ultra high-early strength cement has come to be widely used in the field of concrete. Tests were conducted to clarify the effects of admixtures on the ultra high-early strength cement, selecting some kinds of admixtures with different composition, with reference in particular to the following items:
(1) The kinds and dosages of water-reducing agents that have effect on them
(2) The effect of air entrainment and compressive strength on them
(3) The effect of curing temperature, unit cement content and strength on them
(4) The effect of the time of setting of concrete on them
As a result, it has been found that proper use of an optimum kind of admixtures can also improve the properties of concrete with ultra high-early strength cement as in the case with normal or high-early strength cement.