On 2003 Dec. 20, Japanese Industrial Standard of Ready-mixed concrete, JIS A 5308 was revised to prescribe high strength concrete, improved methods for restraining alkal-silica reaction, materials for ready-mixed concrete i.e. ecocement, silica fume, electric arc furnace oxidizing slag aggregate. This paper describes the outlines of revised JIS A 5308.

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The benefit of polycarboxylate based superplasticizers spreads the widely application of it in Europe and it is occupying about 20% of a market share in concrete admixture. Meanwhile a study and development of the new molecular structure of it has been continued. Recently a unique adaptation combined with SCC especially for the European precast industry has been achieved by a new molecular designing.

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The applications of concrete products tend to increase for their merits such as high quality, short construction period, less construction pollution, less manpower, rational construction, flexibility of product shape and so on. But, the strong vibration noise when the concrete being compacted into the mold during the production process of concrete product is still the problem to be solved for the living-and working-environment. To solve this problem, self-compacting concrete have been applied often in these days. However, the self-compacting concrete produced by conventional superplasticizers require more curing time comparing to normal concrete because of their setting retardation, so that the production cycle time become longer. In this paper, the superior performances of the polyether type superplasticizer with long ethylene oxides chains for self-compacting concrete, high dispersability, minimal setting retardation and high segregation resistance, were described. The better quality, higher productivity and economical merits of the self-compacting concrete with the polyether type superplasticizer were reported.

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In order to evaluate grouted conditions inside the sheath of post-tensioning prestressed concrete (PC), a procedure named Stack Imaging of spectral amplitudes Based on the Impact-Echo (SIBIE) has been developed. SIBIE is an imaging procedure to display a cross-section of the sheath nondestructively by analyzing elastic waves. The theory and applicability of the procedure are discussed and summarized. It is shown that the results of model specimens, a full-scaled PC girder specimen and an existing PC bridge are in remarkable agreement with actual grouted conditions inside the sheaths. Thus, the applicability of SIBIE to evaluating grouted conditions of PC tendons is confirmed.

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There are not many researches to investigate the ultimate shear strength of reinforced concrete members with circular section. In this paper we describe the application of the calculation method of the ultimate shear strength of reinforced concrete members with rectangular section recommended in “the Design Guideline for Earthquake Resistant Reinforced Concrete Buildings based on Inelastic Displacement Concept”, to those with circular section.
The conclusions in this paper are as follows;
1. When the circular section is replaced by the square, it is necessary to decrease 10% of the calculated values.
2. Replaced by the oblong, the calculate value agrees with the experimental results very well.

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Reported is a fundamental study on a development of the newly devised concrete guard fence that is a separated type structure having the upper and lower walls with a buffer part. Static loading test and 3D FEM-nonlinear analysis for both the separated and usual non-separated wall type guard fences of unit width (1 m) are performed, and then the results obtained are compared to show mainly the following three mechanical feature of both types of guard fence :
1. Mechanical behavior of both types of guard fence.
2. Difference of mechanical characteristics due to the use of single and double vertical reinforcements, which connect the upper and lower walls of separated type guard fence.
3. Efficiency of the use of rubber as a shock absorber in buffer part of separated type guard fence.

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