To comprehensively investigate the diversity of a chamfer technology and a convex roll technology under the same soft reduction process (i.e., section size, reduction amount, casting speed and solid fraction), a three-dimensional mechanical model was developed to investigate the effect of the chamfer profile and roll surface profile on the deformation behavior, cracking risk, stress concentration and reduction force of as-cast bloom during the soft reduction process. It was found that a chamfer bloom and a convex roll can both avoid the thicker corner of the as-cast bloom solidified shell, and significantly reduce reduction force of the withdrawal and straightening units. The convex profile of roll limits lateral spread along bloom width direction, therefore it forms a greater deformation to the mushy zone of as-cast bloom along the casting direction, the tensile strain in the brittleness temperature range (BTR) can obviously increase to form internal cracks. The chamfer bloom is much more effective in compensating the solidification shrinkage of mushy zone. In addition, chamfer bloom has a significant decrease of tensile strain in the brittleness temperature range (BTR) areas, which is expected to greatly reduce the risk of internal cracks.

Due to the large amount of binder and low water-cement ratio, high-performance cement composites have high compressive strength and a dense hardened cement paste microstructure. External curing is insufficient, as it cannot reach the interior parts of the structure, which allows autogenous shrinkage to occur in the inside. Lack of prevention of autogenous shrinkage and high restraint causes structural microcracks around rigid components (aggregate, rebars). Consequently, this phenomenon leads to the propagation of internal microcracks to the surface and reduced concrete durability. One way to minimize autogenous shrinkage is internal curing. The use of soaked lightweight aggregate to minimize the risk of cracking is not always sufficient. Sorption and desorption kinetics of fine and coarse fly ash aggregate were tested and evaluated. The correlation between the development of linear autogenous shrinkage and the tensile stresses in the restrained ring test is assessed in this paper. A series of linear specimens, with cross-section and length custom designed to match the geometry of the concrete ring, were tested and analyzed. Determination of the maximum tensile stresses caused by the restrained autogenous shrinkage in the restrained ring test, together with the approximation of the tensile strength development of the cement composites were used to evaluate the cracking risk development versus time. The high-performance concretes and mortars produced with mineral aggregates and lightweight aggregates soaked with water were tested. The use of soaked granulated fly ash coarse lightweight aggregate in cementitious composites minimized both the autogenous shrinkage and cracking risk.