Fig. 12 Scatter of concrete pieces during crushingFig. 13 A beam specimen of W/C=13% after repeated crushing loads showing the shortage of the crushing power─ 6 ─Table 4 Crushing loadMaximumcrushing load(kN)W/C(%)602016133.3 Crushing experiment with a breaking machine(1) Outline of experimentFig. 10 Hydraulic shovel attachmentFig. 11 A specimen held with the attachmentMaximum crushingload ratio tocontrol (W/C=60%)17062395228024521.01.41.31.4loading side (upper side in the Figure) of the load device, and the lower side was fixed and supported the entire specimen. The crushing blade was applied to the specimen, with a total length of 900mm, at the center of a part corresponding to the side surface of the beam 300mm from the end.(2) Experimental resultsTable 4 shows the maximum crushing load of each specimen. Although the maximum crushing load of ultra-high-strength concrete was larger than that of normal strength concrete, it did not change much in the range of W/C=20% to 13%, and the maximum observed with W/C=13% ultra-high-strength concrete members. The crushing load was only about 1.4 times of the maximum crushing load of the ordinary concrete members (W/C=60%).A hydraulic shovel with a maximum hydraulic pressure of 30MPa was used. A crusher produced by company S (SDS250-SRC) was used as an attachment (Fig. 10), where the blade was not a new one, but has been used in the normal conditions. When a hydraulic pressure of 30MPa was applied, the blade was subjected to a load of approximately 800kN.The specimens used in the laboratory crushing experiment were reused and subjected to a bite with both sides of the beam with the attachment to the center part at the horizontal position of 300mm opposite to the side crushed in the laboratory experiment. (Fig. 11).(2) Experimental resultsWhen a crushing load was applied through the attachment, the blade immediately entered the beam specimen of the ordinary strength concrete (W/C=60%), and it was easy to crush and break it. However, in the ultra-high-strength beam specimen as shown Fig. 12, firstly because the compressive strength of concrete was so high and secondarily repeated crushing of the same part after the bounce of the blade and scatter of fine concrete pieces were present (Fig. 13), it seemed to be in lack of the force due to insufficient hydraulic pressure, which was more remarkable when the W/C was lower and the strength level was higher.Nevertheless, when operating attachments as normally
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