Interfacial Transition Zone

The Interfacial Transition Zone (ITZ) is a region of the cement paste around the aggregate particles in concrete.

In ITZ, a gradual transition in the microstructural features occurs.[1] This zone can be up to 35 micrometer wide. [2]:351 Other studies have shown that the width can be up to 50 micrometer. The average content of unreacted clinker phase decreases and porosity decreases towards the aggregate surface. Similalry, the content of ettringite increases in ITZ. [2]:352


  1. ^ a b Scrivener, K.L., Crumbie, A.K., and Laugesen P. (2004). “The Interfacial Transition Zone (ITZ) between cement paste and aggregate in concrete.” Interface Science, 12 (4), 411–421. doi: 10.1023/B:INTS.0000042339.92990.4c.
  2. ^ a b c H. F. W. Taylor, Cement chemistry, 2nd ed. London: T. Telford, 1997.