MASS CONCRETE TEMPERATURE
Problem:
In many mass concrete technical specification, the allowable maximum temperature is 71ºC and temperature difference isn’t more than 20 ºC.
(John Gajda & Alsamsam, “Engineering Mass Concrete Structures”, PCA Professional Development Series, November 2002; John Gadja & Martha Vandgeem, “Controlling Temperature in Mass Concrete”, ACI Concrete International, January 2002; Specification for Structural Cocrete ACI 301-99; ACI 301-99, “Specification for Structural Concrete”)
Reason:
Primary reason is to prevent damage to the concrete. Studies and reseach have shown that the long-term durability concrete could be compromised as long as the range of maximum temperature is not exceeding 71ºC.
The primary damage mechanism is Delayed Ettringite Formation (DEF). DEF can cause internal expansion and cracking concrete, which may not be evident for several years after placement.
Settlement:
In some literature (ACI), it’s required 7-10ºC initial temperature of concrete poured to achieve maximum temperature 71ºC. The efforts to make that initial temperature (7-10ºC) are applying ice, cooling down the aggregate and cement temperature, or other cooling system such as with nitrogen. Those efforts are very expensive.
Many experiences in Indonesia are showing that it’s almost impossible to achieve initial temperature of 20ºC only using ice in concrete mixture without any other efforts and most of mass concrete curing temperature at 80-90ºC.
Does the research prevail in tropical country likes Indonesia? (Does it show concrete damage when maximum temperature exceeding 71ºC in tropical country?)
So, the possible method (to maintain the mass concrete quality) is to maintain the temperature difference of 20ºC.
Source: Concrete Experts
