The term of early age is defined as first ten hours after starting of concrete mixing. The physical and chemical properties of concrete change hardly during the term. Though the sufficient data on the change process of these properties are necessary on concrete work, close investigation on this field have been made little as the tests on placed concrete and have many difficulties. Because the quality control of early age concrete will become important with the growth of use of high fluid agent and high quality retarder, in this paper, we describe the change of properties cared on concrete work.

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Earthquake damages of a foundation by previous strong earthquake motions, are divided into the following two classes. One is caused by the failure of soil layers themselves, and the other is due to the fracture of structural members of a foundation. And systematic rearrangement of a number of foundation damages of reinforced concrete piles by seismic effect, can be classified into the following four typical groups. 1) Foundation construction method, 2) Pile damages of liquefaction, 3) Embankment of dipped topographical geology, 4) Soft soil layer. Especially in 1978 off Miyagi prefecture earthquake, the earthquake pile damages of foundation of a structure in plain soft soil layer in group 4) have attracted special interest recently. In the eatablishment of the aseismic safety design method of a pile foundation it is of most important subject for a future study to clarify the mechanism of pile damages by continuously learning from the earthquake damages.

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In recent years slag has been studied comprehensively and systematically in Japan so as to realize the regular use for concrete aggregate. This paper describes the qualities of air-cooled slag coarse aggregate and granulated slag sand as well as properties of concrete made with these aggregates. Mix design, Construction practices and Performance of slag concrete are discussed in relation with the concrete construction standard specifications, providing the reader with the specific data on the characteristics of slag concrete obtained from many laboratory tests and actual in place experiences, such as workability, pumpability, hardened state properties.

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Recently, concret dam construction tends to be forced to use sea sand when the production of artificial sand is put many restrictions by the economic conditions and the environmental problems. Because the supply of river sand is hardly expected. The authors paid attention to the point that sea sand is no match for artificial sand in view of its stable quantity of supply and quality if it is easy to reduce the quantity of chloride contained in sea sand reasonably. Therefore, the trickling experiments were done and it was concluded to be able to be adopted as aggregate for dams sufficiently. Based on it, we grappled with the salt removal work through the long term of concrete placing and obtained the satisfactory working results. Besides we certified that the troublesome image of quality control dissolved by means of adoption of the method of measuring salinity suited to every scene and the method was well applicable to quality control.

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This paper is a construction record for emperor palace and prince palace of Saudi Arabia. Dece to these constructions belonging to oversea work in the subtropical zone, quality up for construction work periord shortening simplification of wark and specialization of labor as for the goal of labor saving were investigated through all field. As the results, double T shaped slabs were used to the roof for 20--25 m long span of the big space of the main part of the building and so the block method using precast, prestressed concrete was adopted in this construction work By using this method, the above-mentional goals were fully attained and good results were abtained even it was a oversea construction work.

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