Early-Age Drying and Shrinkage Cracking

Water leaves the surface of fresh cement paste, the surface contracts against a restrained interior, and a crack network forms in the first hours, before the concrete has carried any load. Those cracks matter for durability because they give a path to everything that attacks concrete later.

The group measured the drying itself, including experiments under reduced pressure to separate evaporation from the internal transport that feeds it, and built a model for the early-age rate of evaporation and the moisture loss that follows.

The second half of the work is what to do about it. Restrained shrinkage cracking was modelled and measured with and without fiber reinforcement, including alkali-resistant glass fibers and wollastonite micro-fibers, and quantified in two dimensions by image analysis of the crack pattern rather than by a single crack width reading.

This is also the subject of a keynote at the International Conference on Durability of Concrete Structures in Leeds in 2018, and of lectures in the Politecnico di Milano summer school, whose slides are on the presentations page.