Some methods to maintaining the beauty of concrete structures were discussed. The mechanisms to causing the soiling of concrete surface were explained. The influences of the detail and the shape of building on soiling were investigated and an evaluating method of soiling was indicated. The aging of concrete structure was discussed and appropriate methods to maintaining the beauty of concrete structures were proposed.

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22 storied apartment house which planed to have four dwelling units facing south in each floor was constructed. Distinctive features of the plan of the building were flexible dwelling space with span of 7 to 7.5 meters and shear walls arranged between each unit. High strength concrete which specified design strength of 600 kgf/cm2 using silica fume was applied to improve strength and workability of concrete. This report describes the mixture design, production, construction and quality control of high strength concrete using silica fume.

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One of two LNG inground storage tanks with the world largest capacity of 200000kl, which have been under construction at the Negishi Terminal of Tokyo Gas Co., Ltd, was completed last November. This new tank is the landmark of the development for large capacity and shall be also the starting point. Many latest technologies have been adopted for this project and technological features are following as vertical NATM of soft rock, highstrength concrete of 600 kgf/cm2, RC doomed roof and automatic construction technology. The merits of inground storage include (1) higher safety, (2) effective use of land, (3) well harmony with scenery. Newly developed technologies as RC roof and high-strength concrete, are highly improved to the merit of inground storage tank, higher safety and the effective use of land. In this report, the development and construction of the side wall with highstrength concrete and the concrete doomed roof is described.

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The Tedorigawa River Bridge is located at the mouth of the Tedorigawa River, which flows through the center of Isikawa Prefecture. The bridge has been subject to salt attack from more than ten years ago, due to the airborne salt content of the wind from the Japan Sea. As the bridge was damaged extensively, the surface was covered with epoxy resin paint containing glass fabric over three years, from 1983 to 1985. The salt content which had permeated into the concrete was not completely removed, however, and the damage again became extensive, occasioning the need for urgent measures, such as cutting away, in principal, all conditions for the repair work were as follows : (1)The entire superstructure surface had to be cut away, a task which would require considerable labor and time if carried out manually. (2)The risk of spalling due to insufficient adhesion existed, as the replacement concrete had to be poured in a thin lift, and no steel reinforcements existed in the layer to be replaced. (3)The work had to be carried out, in principle, while the bridge was in service (in other words, while subject to the vibrations from passing traffic). (4)A large amount of concrete placement had to be carried out in inverted order, because the bridge girders had to be repaired.
To cope with (1) in advance of the work, a system to cut away the entire surface with a super-high-pressure water jet as well as the necessary control system were developed to make the cutting process more efficient. For (2), (3) and (4), a technique to select materials for the inverted placement of concrete under vibration was developed and successfully employed, and a test to measure the load-bearing capacity of the remedial concrete as well as a method to carry out the repair work were also developed. This paper outlines these processes and reports on the applicability of the systems it is believed that tha data will be of use in future repair work dealing with damage from salt attack.

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In the Hanshin-Awaji Great Earthquake, which broke out at 5 : 46 a.m. on the latest Jan. 17. our Sanyo Shinkansen was seriously damaged, and its bullet train service between Shin-Osaka and Himeji Terminal had been disrupted until Apr. 8, the 80th day after the quake-attack. Therefore, in this paper, we briefly mentioned the structural damage on our Shinkansen facilities (viaducts, bridges, and so on) in addition to the outline of Shinkansen network, and introduced our presumption that the Instant Shear Failure of RC pillars caused the collapse of such pillars, which closely related to the viaduct/bridge-beam falls in this earthquake. Also, we mentioned the Steel-Plate Encasing Method, adopted as the most effective way to restore the damaged pillars, and indicated high increase of both toughness and quake-resistance of the restored pillars under this method. As, more-over, placing the fallen viaduct-slabs/PC bridge-beams at their right position safely had been another big problem, we briefly mentioned some methods adopted to execute such troublesome works well, and finally made a list to show the average form of steel-plate and grouting methods used in the process of the Steel-Plate Encasing Method.

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As the symbol of Kuala Lumpur City Centre Project, twin towers have been constructed, and each of twin towers (Tower One & Tower Two) has 88 floors. The complex structure of this tower consists of external tube with reinforced-concrete columns and beams, and steel frame beams connecting the columns and beams to the internal reinforced-concrete core-wall. The high-strength concrete of 80 MPa is designed for the structural members. The construction of this tower should be finished in 29-months, therefore the high-speed construction method have been achieved at rate of one floors in four days, by working day and night. This report describes the outline of this structure, construction method and quality control of high-strength concrete.

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