Abstract: A concrete surface layer fragmentizing method of fragmentizing a surface layer of a concrete structure by a jet formed by ejecting high pressure water from a nozzle. The method comprises adjusting control parameters for controlling the ejection and movement of the jet, including a fragmentation width, a standoff distance, ejection water pressure, ejection water amount, nozzle lateral movement speed, and the number of nozzle swing times; and sweeping the jet over a predetermined range so as to fragmentize only deteriorated concrete deteriorated in strength with leaving sound concrete (selective excavation).

Abstract: In the present invention, testing is performed by injecting grout (G) into a full-scale specimen comprising a cable that is fabricated at a place other than a construction site. The cable has a sheath made of a transparent material and has the same three-dimensional configuration as that of an internal cable (2°) at the construction site. Alternatively, grout (G) is injected into a partial specimen comprising a lengthwise part of the cable where an air trap is likely to occur. The testing is performed under a plurality of different testing conditions. The best grouting conditions are selected from testing results and applied to grouting actually carried out at the construction site.

Abstract: A method of inspecting a concrete surface. The method comprises ejecting highly pressurized water to a concrete surface by using a jet nozzle, thereby fracturing and spalling off deteriorated concrete deteriorated in strength, with leaving only sound concrete, for inspection of surface strength.

Abstract: The present invention relates to a method for recovering water permeability of a pavement surface layer of drainage or water permeable pavement by removing clogging of air voids in the pavement surface layer, comprising the step of: discharging water jet at a high pressure from a nozzle onto a surface of the pavement surface layer so that the surface of the pavement surface layer is within a droplet flow region of the water jet and that droplets and globules in the droplet flow region enter the air voids in the pavement surface layer to cause water hammer which removes the clogging of the pavement surface layer.