1960 Volume 1960 Issue 71 Pages b1-b16
In this paper, the author describes a compacting method of concrete of centrifugally spun precast reinforced concrete piles. Testing through the hollow-spun specimens made by the special apparatus, the minimum number and time of revolutions necessary to make the hollow form, and next in this speed range, the minimum number and time of revolutions required to obtain the manimum strength of concrete at low, middle, and high speed revolutions are investigated. Consequently at the low speed revolution, a most suitable speed and time for concrete slump are obtained. At high speed revolution, concrete strength is highest when the spun effect (E=kn2t1/2) is constant. R. p. m. of middle speed revolution is given by n′=n/√2.