This report presents essential points in designing the concrete used for Sub-surface LLW disposal facility, in terms of the required performance and techniques. Especially from the viewpoint of system performance, long-term durability (e.g. over 10,000 years) of cement materials needs to be further investigated. An accurate evaluation method for the cement dissolution rate is required so as to evaluate the transition of concrete physical properties and the deterioration of Na-type bentonite materials under the high alkalinity. In the conceptual design of the facility, it is considered that the dissolution of cement materials progresses very slow from the surface and also considered that taking countermeasures to reduce the cement dissolution contribute to the improvement of durability of the engineered barrier system.

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Over reaction of the general public and the media against reporting for Asbestos and its health damage are induced by a shortage of holding a shared sense. From this point of view, the data base required to hold a shared sense, such as total construction floor area, import amount of Asbestos, production of interior and exterior board, death and causes of death are presented in this paper. Based on these databases, it is concluded that many benefit have been brought to a people by building construction and building material containing Asbestos. Lastly, it is mentioned that holding of a shared sense and establishment of agreement formatting for relationship between risk and benefit based on the objective, technological, and quantitative judgment should be hurried.

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Many apartments are increasingly being built as super high-rise reinforced concrete buildings, particularly in metropolitan areas, and thus the usage of ultra-high strength concrete and reinforcing bars is increasing. However, the existing design recommendations of public organizations are for concrete of compressive strength not exceeding 60 N/mm² and main reinforcements of SD390 or lower. In this study, a database which compiled experimental results of bending shear tests on reinforced concrete columns or beams using concrete of more than 60 N/mm² for compressive strength was constructed in order to investigate the suitability of several proposed equations for strength estimations.

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The accelerated test was carried out in order to construct degradation prediction model by the compound of neutralization and salt damage and by sulfate corrosion. The promotion neutralization test of the concrete including the chloride was applied in the characteristic grasp of the complex deterioration of neutralization and salt damage. And, the immersion test to sulphuric acid solution was applied in a grasp of the degradation under the sulfate corrosion environment. In the modeling of the degradation prediction, reaction model was added to the diffusion equation which was related to the phenomenon. As a result of comparing with the analytical result according to degradation prediction model proposed with test result, the prospect which proposed model could apply to the degradation prediction was obtained.

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Durability performance of concrete structures to external aggressive actions strongly depends not only on the cover thickness of the members but also on the resistance of cover concrete “Covercrete”. This paper introduces non-destructive in-situ air permeability test methods for “covercrete” mainly based on the draft version of state-of-the-art-report prepared by RILEM TC 189-NEC “Non-destructive methods to measure air-permeability”. The scope of the TC includes (a) Selection of suitable non-destructive test (NDT) methods for the evaluation of the thickness and quality of the covercrete, in view of the durability of concrete structures, (b) Draft recommendations for the application of those test methods, (c) Establish guidelines for the specification of the quality and thickness of the concrete cover, as function of exposure conditions and service life design, and for its compliance control in-situ by NDT methods. In this paper, an outline of the comparative test to achieve the scope “(a)” is also introduced.

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