Abstract: An unbonded PC steel strand used for posttensioning concrete comprising a PC steel strand composed of a plurality of stranded wires, a thin transparent lacquer coating on the outer surface of the PC steel strand, the lacquer coating being able to be broken when the PC steel strand is subjected to tension or posttensioning concrete, a filler applied around the lacquer coating, and a synthetic resin sheath covering the lacquer and filler coated PC steel strand. A method of manufacturing the unbond PC steel strand comprising steps of annealing the PC steel strand at a low temperature to remove strain, coating the outer surface of the PC steel strand with lacquer, applying a greaselike corrosion inhibitor to the surface of this lacquer coating, and sheating the coated PC steel strand with an outer synthetic resin sheath.

Abstract: An unbonded PC steel strand used for posttensioning concrete comprising a PC steel strand composed of a plurality of stranded wires, a zinc plated layer on the outer surface of the PC steel strand, a greaselike filler applied around the zinc plated layer, and a synthetic resin sheath covering the zinc and filler coated PC steel strand. A method of manufacturing the unbonded PC steel strand comprising steps of pickling and water washing the PC steel strand, coating the outer surface of the PC steel strand with flux, plating the outer surface of the PC steel strand with zinc, applying a greaselike corrosion inhibitor to the surface of the zinc plated layer and sheathing the PC steel strand with an outer synthetic resin sheath.

Abstract: An interchange system serving elevated railways and roadways intersecting each other, which system comprises a rotary possessing of a cylindrical plaza at the center thereof and an annular bus stop compound along the periphery of the plaza, a railcar platform above the rotary, interconnecting passages between the plaza, the bus stop compound and the railcar platform and tunnel-like passages dug across under the rotary to reduce a difference between the levels of the plaza and pedestrian paths formed along the opposite sides of the roadways, thereby to ensure the safety and convenience of pedestrians.

Abstract: A blast-furnace tuyere having excellent thermal shock resistance and high durability consists of a tuyere substrate composed of copper or copper alloy, a self-fluxing alloy metallized layer sprayed on the substrate, a cermet coating sprayed on the alloy metallized layer, and a ceramic coating sprayed on the cermet coating. The cermet coating is made from a mixture of an alloy material consisting essentially of 5 to 60 wt% of Co, 5 to 50 wt% of Ni, 5 to 25 wt% of Cr, 5 to 40 wt% of Mo, 5 to 40 wt% of W, 3 to 40 wt% of Si and inevitable impurities, and a ceramic eutectic material consisting essentially of 95 to 65 wt% of Al.sub.2 O.sub.3, 5 to 30 wt% of ZrO.sub.2, 2 to 20 wt% of TiO.sub.2, 3 to 30 wt% of SiO.sub.2 and inevitable impurities. The ceramic coating is made from the same ceramic material as used in the formation of the cermet coating.