Fig. 5

Schematic diagram of special mold A Overview of mold freezing system. 1.boxes containing liquid nitrogen and warm water 2.drainage rod 3.clamps with tendon 4.mold 5.collection box B. 1.boxes containing liquid nitrogen and warm water 2.drainage rod 3.clamps with tendon 4.mold 5.collection box. The whole system consists of three layers. The top layer is two boxes containing liquid nitrogen, sandwiched by boxes containing warm water. The middle layer is the mold with clamps, and holes shall be drilled on the mold to ensure liquid infiltration. The bottom layer is a collection box to collect the liquid flowing from the middle layer. The bottom ends of the three boxes on the top layer shall be perforated, and drainage rods shall be installed next to the bottom holes of the liquid nitrogen boxes at both ends to make the liquid nitrogen flow to the clamp along the drainage rods. The central warm water box is perforated in the middle so that it is located on the same vertical line as the center point of the tendon in middle layer. C. The clamping part of the tendon in the mold group was completely frozen, but the test part was not frozen