Development of Self-Compacting Concrete For several years beginning in 1983, the problem of the durability of concrete structures was a major topic of interest in Japan. The creation of durable concrete structures requires adequate compaction by skilled workers. However, the gradual reduction in the number of skilled workers in Japan's construction industry has led to a similar reduction in the quality of construction work. One solution for the achievement of durable con- crete structures independent of the quality of construc- tion work is the employment of self-compacting con- crete, which can be compacted into every corner of a formwork, purely by means of its own weight and with- out the need for vibrating compaction (Fig. 1). The necessity of this type of concrete was proposed by Okamura in 1986. Studies to develop self-compacting concrete, including a fundamental study on the work- ability of concrete, have been carried out by Ozawa and Maekawa at the University of Tokyo (Ozawa 1989, Okamura 1993 & Maekawa 1999). The prototype of self-compacting concrete was first completed in 1988 using materials already on the mar- ket (Fig. 2). The prototype performed satisfactorily with regard to drying and hardening shrinkage, heat of hydration, denseness after hardening, and other proper- ties. This concrete was named "High Performance Con- crete" and was defined as follows at the three stages of concrete:

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Self-Compacting Concrete

This paper presents the experimental results concerning the mix design and fresh properties of a high-performance fibre-reinforced fine-aggregate concrete for printing concrete. This concrete has been designed to be extruded through a nozzle to build layer-by-layer structural components. The printing process is a novel digitally controlled additive manufacturing method which can build architectural and structural components without formwork, unlike conventional concrete construction methods. The most critical fresh properties are shown to be extrudability and buildability, which have mutual relationships with workability and open time. These properties are significantly influenced by the mix proportions and the presence of superplasticiser, retarder, accelerator and polypropylene fibres. An optimum mix is identified and validated by the full-scale manufacture of a bench component.

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Mix design and fresh properties for high-performance printing concrete

Hardened properties of high-performance printing concrete

The effect of silica fume and high-volume Class C fly ash on mechanical properties, chloride penetration and freeze-thaw resistance of self-compacting concrete

Hajime Okamura

Papers

Self-Compacting Concrete

1001 A Rational Mix-Design Method for Mortar in Self-Compacting Concrete

2060 Quantitative Evaluation Method for Effect of Superplasticizer in Self-Compacting Concrete

Hallway exploration-inspired guidance: applications in autonomous material transportation in construction sites

Computational model for chloride concentration in concrete under atmospheric environments