PC-Rev Method

Recent studies have shown that sometimes grout does not completely fill the intended space with conventional materials and methods. Thus, there are concerns that existing structures may lack durability due to cavities in the grout. The PC-Rev method can renovate concrete structures while the prestressed steel is still relatively sound by drilling through the sheath with a super-low-vibration drill, estimating the cavities inside the sheathing, and then filling the cavities with grout using a snake pump.

Small-diameter drilling with sheath detected type

• A super-low-vibration drill with a long drill bit (LGD-B1) can drill through concrete without causing any damage around the drilling site. By using the same small-diameter hole for both measurement and grout filling, the load on the concrete structure can be reduced.

Measurement of cavities inside sheath

• Cavities inside the sheath are estimated accurately by measuring pressure changes with decompression equipment connected to the sheath.

Grout filling with switching valves

• The volume inside the sheathing is decompressed with a vacuum pump, and the low pressure draws grout into the cavities. After that, switching valves are used to pump more grout into the sheath with a snake pump, which produces a smoother flow. Finally, pressure is added inside the sheath.

Rust-resistant grouting material

• Corrosion of prestressed steel is suppressed by adding calcium aluminate, which can immobilize hazardous soluble chloride ions by crystallization.

Application of PC-Rev method