Crack formation in cementitious materials may start when the material is still in its plastic stage. Water loss in this very early age causes a curved water surface between the solid particles at open boundary faces. The resulting capillary pressure…
Crack formation in cementitious materials may start when the material is still in its plastic stage. Water loss in this very early age causes a curved water surface between the solid particles at open boundary faces. The resulting capillary pressure leads to the so-called plastic or capillary shrinkage. At a cer- tain material specific pressure, air penetrates locally into the pore system and cracks may originate from these locations. If air entry is prevented; i.e., if the absolute capillary pressure value is kept below a critical limit, this type of crack initiation does not occur. Results of the capillary pressure measurement in plastic cementi- tious materials are presented and a method of capillary pressure controlled concrete curing is proposed. By using a discrete particle-based model, capillary pressure induced crack initiation may be simulated. Further- more, it has been shown by Finite Element analyses that concrete cracks formed already in the plastic stage affect the behavior of the structures in the hardened s tage. Capillary shrinkage cracks might degrade the dura- bility of concrete structures.