2023-06-08 06:00:02
Shimizu Corporation has succeeded in printing a parking lot roof structure by applying a concrete structure with a 3D printer. This is the first application of “Structural Raktum”, which was developed in-house as a concrete material for 3D printing, to print construction of building structures.
The applicable property is the roof structure of the parking lot developed in the Shiomi Innovation Center (provisional name), a company facility under construction in Koto Ward, Tokyo. A “printed structure” constructed by laminating structural lactum was applied to a part of the arch-shaped structure surrounding the outer periphery of the membrane roof. As a concrete formwork for the slanted pillars that support the roof, a “printed structural formwork” that can be included in structural calculations as part of the structure is also used.
Structural Raktum is a concrete material made by kneading coarse aggregate into the fiber-reinforced cement composite material Raktum, which was originally developed for 3D printing in 2020. Laktum can be laminated to a height of 2m or more while maintaining its shape, and the laminate has mechanical properties and durability equal to or greater than those of ordinary concrete. It was difficult to apply it as a structural member due to the restrictions of , and the range of utilization was limited contrary to its performance.
Therefore, we have newly developed Laktum for concrete materials and structures by kneading coarse aggregate into Laktum. Acquired certification from the Minister of Land, Infrastructure, Transport and Tourism as a designated building material that can be used for the main structural strength of buildings. This will expand the range of applications for 3D printing in buildings, which was previously limited to non-structural members and finishing members. While realizing labor saving and manpower saving in construction, it became possible to minimize the cross section of members by using printed material as a structure. Structural Raktum is the only 3D printing material in Japan that has received ministerial certification as a designated building material.
The printed structure applied this time was formed by repeatedly laminating structural laquetums and laying reinforcing bars between predetermined printed layers using a robot arm type 3D printer. Structural laktum, which has the same performance as high-strength concrete, has high shear strength, so the structural performance required for the members is secured only by the main reinforcing bars laid in the axial direction between the stories. In order to achieve the optimal structural shape, the cross section of the member is made into an arch shape that changes gradually, and by finely controlling the nozzle movement speed during printing, the complex shape is directly formed.
The printed structural formwork used for constructing the slanted columns also functions as a structure for the RC columns. This makes it possible to reduce the amount of concrete poured into the formwork and minimize the cross-sectional area of the entire member compared to using a non-structural printed formwork, thereby realizing a rational frame design. It has become possible.
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