Cracking risks associated with early age shrinkage

When assessing the cracking potential of concrete it is critical to refer to the total shrinkage: both early age and long-term deformation, in both drying and autogenous conditions. A Finnish test arrangement has been used to measure linear and volumetric deformations of concrete immediately after mixing. The slabs are tested in either drying or autogenous conditions. Long-term shrinkage can be measured on the same slabs to give an accurate representation of the total free shrinkage. From these measurements it is possible to assess the likelihood of cracking due to early age shrinkage. Results have shown that both drying and autogenous shrinkage can be significant in certain early age scenarios. Environmental factors greatly affect drying shrinkage, while material properties affect autogenous shrinkage. This paper provides insight regarding how to interpret early age deformations, how environmental and material factors play a role, and how to minimize shrinkage and thus cracking potential in the early ages. (C) 2003 Elsevier Ltd. All rights reserved.