This paper aims that we clarify the mechanism on the impact-wear and the resistance of the concrete against the impact-load. We have designed a special test-machine to perform this trial. The test-machine has a structure as figuare-1. Lift up the steel balls (φ=52mm,
W=590g, HRC= 52-58) autmatically by the chain conveyer and fall them down continuously at 10 times one minuit_
The results are as follows :
1) The phenomena of impact-wear on the concrete surface may be so called the virgin-wear.
2) We are able to test the resistance of the concrete against the impact-load by the Ros-angeles test of aggregates.
3) The resistance of concrete against the impact-load has the nearlly maximum at an age of about 10 or 14 days and is likely increased by the following conditions,
(1) to use fine aggregates.
(2) to lessen the water-cement ratio.
(3) the weight ratio of cement to fine aggregate is the best at from 40-50 %.
4) The resistance of concrete against the impact-load seems to be estimated by the compressive strength.
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