This paper deals with the influence of conveyance vibration on compressive strength of specimen of high-strength concrete. In the experiment, six kinds of concretes (water binder ratio is 60% to 20%) were examined. Conclusions are as follows. (1) The conveyance vibration affects compressive strength of specimen. Immediately after production of concrete, conveyance vibration causes strength reduction of specimen. Then, if concrete begins to harden, conveyance vibration will contribute to the

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... ovement in compressive strength. Furthermore, if time passes too much since production of concrete, conveyance vibration will cause strength reduction. (2) Concrete with low water binder ratio is hardly subject to the influence of conveyance vibration. One of the reasons of this is that water and air hardly move in concrete with low water binder ratio. (3) It is not desirable to carry a test specimen immediately after mixing of concrete. Moreover, after time passes very much since mixing of concrete, it is not desirable to carry a test specimen, either.