| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for determining time of demolding the concrete that simply and accurately estimates the strength when demolding the concrete of a young material age on the way of curing like the coating concrete of a mountain tunnel. SOLUTION: An internal temperature is measured at the end of the crown part 3 of a centering when casting the coating concrete 2 of a tunnel 1 (step 1), a cubic test piece and a columnar test piece, both of which includes the same material of on-the-spot concrete, are made to be aged in a thermostatic ageing chamber to which a measuring temperature is applied (step 2), the measurement of the degree of repulsion of the cubic test piece due to a pendulum type hammer tester and the uniaxial compression test of the columnar test piece are performed at the same time to obtain the degree of repulsion and a uniaxial compression strength curve (step 3) in an elapse of 16 to 24 hrs, the form of the end is partially detached and the degree of repulsion of the on-the-spot concrete is measured by the pendulum type hammer tester and the compression strength of the on-the-spot concrete is estimated using the curve (step 4) and, if the on-the-spot concrete reaches predetermined demoldable strength, the whole of the centering is lowered to demold the concrete. COPYRIGHT: (C)2009,JPO&INPIT
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