PSI - Issue 11

Iara Silva et al. / Procedia Structural Integrity 11 (2018) 130–137 Iara Silva et al. / Structural Integrity Procedia 00 (2018) 000 – 000

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element or crack in the concrete, since the existence of these types of defects characterizes the non-fulfillment of the test requirements. (AREMA (2013)) After the successful completion of the insertion pullout test, the torque test was also performed at each insertion. A torque of 339 N.m was applied around the vertical axis of the insert by means of a calibrated and perfectly adjusted torque wrench, shown in Fig 7.b. The torque was maintained for 3 minutes.

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b

Fig. 7. (a) Pullout Test Execution (b) Torque Test on the insertion

7.3. Adherence Test

As the sleeper was supported and loaded according to Fig. 6, an increasing load with a rate not exceeding 22 kN/min was applied until a total value of 392.57 kN was obtained. The load was maintained for a period of 5 min, during which the sliding of the outermost prestressed wire or rope of the lower layer of the active rebar was read through a 1/1000 scale dial indicator, shown in Fig. 8. The requirements of this test were met in cases where the sliding of the prestressed wire or rope did not exceed 0.025 mm (1/40 mm), and in the absence of compressive failures and cracks in concrete or defects in steel.

a

b

Fig. 8. Adherence test: (a) dial indicator positioning; (b) rope sliding measurement

8. Results

The results obtained after the inspection and the tests with the recovered concrete sleepers were satisfactory, taking into account the values specified in the Standard (AREMA and ABNT). The recovered sleepers presented behavior similar to conventional sleepers. The dimensions of the sleepers were not affected by the applied treatment, which was able to seal the existing cracks, and there was no impairment of their mechanical behavior in response to the stresses applied during the verification and quality control tests. Besides, it was possible to verify that the presence of these defects due to the manufacturing process, did not show relation to structural causes that could compromise the capacity and performance of the piece, becoming viable its recovery by superficial treatment, as in the case of crystallization by painting.