The New Material Comprehensive Project sponsored by MOC has finished this March with a 5 year duration. In this paper outline of 3 items in guidelines of the use of the concrete building structures reinforced with continuous fiber reinforcement, which is developed at the Project, is described. The items are the design guideline of ordinary concrete structures, the main points of the use of prestressed concrete construction and the use of 2 and 3 dimensional fiber reinforcement. The objectives of the Project are to develop the use of continuous fiber reinforcement as substitute of steel reinforcement and tendon.

View full abstract

The quality of ferro-nickel slag as fine aggregates for concrete was standardized into JIS A 5011 at October 1992. In response to this standardization, the Japan Society of Civil Engineers and the Architectural Institute of Japan intended to publish respectively “The guidelines for concrete using ferro-nickel slag as fine aggregates”. This paper explains the quality of ferro-nickel slag fine aggregates standardized in JIS and the recommendation of the concrete using the ferro-nickel slag in both guidelines. In these guidelines, ferro-nickel slag fine aggregates are recommended to blend with natural sand but also single use. The main aims of the blended sand are improvement of particle size distribution and/or the decrease of chloride content in natural sands. In general, the ratio of ferro-nickel slag in the blended sand should be limited less than fifty percent.

View full abstract

This paper presents the inspection result of the cracks due to the Alkali Aggregate Reaction to the reinforced concrete slab of the road bridge. All data was derived from the track record over the decade and the load endurance test results performed on the test pieces which use a reactionable aggregate. The integrity judgement and maintenance method are suggested based on these studies. The crack was initially observed by the regular inspection. A phenomenon of crack differs from the ordinary case caused by the live load of the traffic and tends to occur in the same construction section. A behavior of crack extension and density, the rate of the crack density in axis and in perpendicular to the axis the bridge indicates unique characteristics during the following inspection. A static load test result on the actual bridge does not indicate any decrease of stiffness that corresponds with the result of the load test on the test pieces. As a result of the series of test, the installations of the water proof layer on the slab aiming to avoid progress of the Alkali Aggregate Reaction by the water and the epoxy bonded steel plates with grouting to the cracks on the back side of the slab are recommended in the aspect of durability of the slab.

View full abstract

The Daia-City 2000 Moniwa, constructed in a suburb of the City of Sendai, is the first reinforced concrete high-rise condominium building with 33 stories in the Tohoku District, and is a symbol of a new-town project with 9 buildings having total 927 houses. Adopting a integrated construction method, that is, using precast concrete members fabricated at a site shop as well as many other construction methods saving construction labor and resources, construction of the building was completed efficiently. It was the first time to use high-strength concrete of 480 kgf/cm2 (47 MPa) to building construction in the Tohoku District. To control the quality of high-strength concrete at the site, technical consulting to ready-mixed concrete plants and testing for concrete were conducted. The report discribes the fabrication of precast concrete members, construction of a precast concrete structure and quality control of high-strength concrete.

View full abstract

There are so many problems like narrow site space, overlapping works and limited available cranes to construct a Railway bridge in a great city. To make its at Akabane station and its connections for an example of these severe conditions using precast elements, we compare the structural system, the construction period and the actual cost with that of an ordinary way. After considering them, we apply the RC half precast slab for the Tohoku passenger and freight line and try to adopt the PC half precast slab for the Tohoku line. This report describes the outline of making railway land bridges using prefabricated members.

View full abstract