ABSTRACT
In conventional tunneling, initial strength, long-term strength and bonding properties of shotcrete are significantly affected by the type and content of setting accelerator. Setting accelerator performance is highly dependent on temperature, and changes in base concrete temperature can affect the quality of shotcrete. The authors have developed “Smart Batcher Plant” that automatically controls the as-mixed temperature of concrete and produces concrete of stable temperature. The plant was field-tested at a road tunnel construction site in a cold region where the lowest temperature in winter can falls to 20°C below the freezing point. This paper briefly describes the Smart Batcher Plant and reports on the field validation of the automatic as-mixed temperature control function, the results of comparison with the conventional construction method, and the verification of quality and workability improvements and cost reduction accomplished by achieving target temperatures.
