cementtisauma

Cementtisauma is a term used in civil engineering and materials science to describe a planar seam of cementitious material that can occur within concrete. It is observed in both cast-in-place and precast elements and can influence the material’s behavior under load and exposure conditions.

Definition and appearance: a cementtisauma is a narrow, continuous plane where the cement paste concentrates, forming a seam-like feature that runs parallel to a structural plane or along a joint. The seam may show a different microstructure and porosity compared to the surrounding paste, sometimes producing a visible contrast in colour or texture.

Formation and causes: cementtisauma can form during casting when segregation of aggregates and paste occurs, during bleeding as water migrates through the surface, or through differential curing and shrinkage. Interfaces created by multi-pour construction, restraints, or thermal gradients can enhance seam development. The result is often a region with distinct paste composition and microcrack pattern.

Properties and implications: the seam’s width can range from micrometers to millimeters and its length may span a substantial portion of the element. It can affect permeability, bond strength with overlays or repair materials, and may act as a preferential path for moisture, chlorides, or crack propagation under stress. In some designs, extended seams are avoided, while in others they may be tolerated or even exploited to create intentional joints.

Detection and mitigation: non-destructive methods such as ultrasound or X-ray imaging, along with surface inspection, help identify cementtisauma. Mitigation focuses on improving mixing uniformity, minimizing segregation, controlling temperature during curing, and careful placement and compaction to reduce seam formation.

See also: concrete microstructure, paste-aggregate interface, shrinkage cracking.