Technical Questions

ACI Committees, Membership, and Staff have answered common questions on a variety of concrete related topics.



Pozzolans in mass concrete

Q. What are the benefits of a pozzolan in mass concrete or in massive structural concrete?

 

A. Used as a portion of the cementitious material in large amounts (usually more than 15% by mass of the cementitious material, depending on the amount and time of strength requirement), a pozzolan reduces the rise in temperature up to one-half of what the portland cement would have generated, thereby helping to control temperature differentials that cause cracking due to cooling (ACI 207.1R). The continuing chemical reaction of the pozzolan with lime sustains and increases strength development at later ages well beyond 28 days, especially when the pozzolan is used in larger amounts in low cementitious material (lean) concrete.

 

References: SP-1(02); E3-13; ACI 207.1R-05; ACI 232.1R-12; ACI 232.2R-03; ACI 234R-06; ACI PRC-232.4-20; ACI 211.1-91

Topics in Concrete: Pozzolan; Cementitious Material; Mass Concrete

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