Original paper(Vol.45 No.9 pp.985)

Fundamental study on the control of setting time of fresh concrete

Takeuchi Tohru; Nagataki Sigeyoshi; Otsuki Nobuaki; Sakamoto Takeru

Abstract:The diversity of concreting methods in recent years has led to a demand for long retardation of concrete setting. Conventional research has achieved retardation for up to about 3 days by the addition of a set retarder, but few studies have dealt with concrete that is placeable after a much longer period.
This paper reports the effects of the set retarder dosage and temperature on the slump, period of set retardation, time limits for superplasticizing and compressive strength of concrete. The usability of concrete with long-retarded setting is discussed as well.

Key Words:retarder, setting time, slump, time limit of superplasticizing, compressive strength