“At first, this section was just an earth canal, dug by hand, and seepage was serious,” said He Qiang, project manager of Section 6 of the Daqing Canal works. Later, hexagonal precast slabs were installed, but they did not last long either. Peeling, sand shedding, and frost heave damage became routine, and half the canal was clogged with silt. “The irrigation of 89,000 mu (59.33 hectares) of farmland was always under pressure. Every irrigation season, we had to rely on dredging boats,” he said.

　　Winter temperatures are too low for construction, leaving only two workable windows each year: more than 40 days before spring irrigation from March to April, and about 50 days after autumn irrigation from September to October. “All told, we only have about a hundred days a year to work,” He said.

　　This time, the team introduced a factory-based prefabricated reinforced concrete rectangular canal design. On site, rows of concrete components were neatly arranged. The prefabrication plant can produce and shape these components in 28 days before transporting them for assembly.

　　During installation, expansion waterproof strips are inserted between each slab, and epoxy resin mortar is applied to the outside as well. As He demonstrated with a level at the joint, the surface was flat and the seams were almost invisible. “It’s a double-layer anti-seepage system, and the concrete can fully withstand severe cold.”

　　He calculated that for a 5-kilometer canal, traditional cast-in-place construction would require 300 workers, while prefabricated assembly needs only 150. In addition, earthworks and prefabrication can proceed in parallel, without waiting for concrete to cure.