Although mixing is very important when producing concrete, mechanism of mixing is complicated and difficult to analyse. Due to recent developments of new mixing methods, mixers, and admixtures, people get interested in the mixing of concretes. This paper explains importance of mixing, types and kinds of mixers used in our country, test methods for mixers and their problems, and mechanism of mixing.

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Since coating system for concrete structure has been developed progressively, they are realized as reliable and good performance materials. Coating system is used not only concrete appearance but protecting from salt damage and repair of concrete recently. In this paper, role and design of coating system in application areas, recent structures applied with coating system, and newly developed coating materials are discussed.

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This 20 story condominium building which is the symbolic tower in SHIGI NEW TOWN project was designed a irregular plan of zigzag shape dueto architectural desire. To rationalize aseismic design of irregular structure, the newly structural system of framed tube and Composite structure was employed for the first time in high-rise R/C buildings. For rationalization of Construction work, prefabrication system of steel-reinforcing assemblage was developed.

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Tsing Tsuen Bridge crosses the 260m wide Rambler Channel. This is the largest prestressed concrete bridge in Hong Kong. The main piers are supported on 28 large diameter (2.1m) bored cast in place concrete piles through pile caps. The pile cap is quite large being 6.6m deep by 45m long by 16m wide. An elegant solution (Jack Down System) was used to overcome the problems of constructing the pile caps most of which are in the sea. The solution adopted was to concrete outer shell of the pile cap (the bottom and sides) above the water level. This assembly was then lowered using jacks onto the piles and circumferential gaps between the piles and the bottom slab sealed. In this report, the construction method and some technical advices are introduced.

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