Setting Times of Fly Ash and Slag-Cement Concretes as Affected by Curing Temperature

Using Test Method for Time of Setting of Concrete Mixtures Paste by Penetration Resistance (ASTM C 403), Proctor penetration resistance was determined under isothermal curing temperatures ranging from 6 to 80°C for concretes containing up to 50% of fly ash or ground-granulated blast-furnace slag. The results show that as the temperature increases, the initial and final setting times decrease for all types of concrete, with fly-ash concrete having the longest setting times. At high temperatures, slag concrete has shorter setting times than Type I cement concrete. Relationships are presented for setting time as a function of penetration resistance, temperature, and cement replacement level.