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2013FallShotcreteEMag

Goin’ Underground spraying a thin skin liner onto excavated material The surface was good enough to be sprayed and to spray some test panels to check that this onto without additional preparation. For rougher method of construction is feasible and also surfaces, applying a 25 mm (1 in.) smoothing provides structural bond requirements between mortar might be required. The TSL cured well the thin skin liner and the sprayed concrete, and was successfully sprayed over with sprayed described next. concrete. Hagerbach test panels, July 2011—Encouraged testing by the success of the initial trial, more testing was A shaft construction site in London, June 2011— proposed to test the capability of both Masterseal With the assistance of BASF, the client, and the 345 (sprayed membrane) and MEYCO TSL 865 contractor, trials were carried out at the SCL shaft (thin skin liner) for early strength and bonding to construction site in London in June 2011 in order to freshly sprayed concrete at early curing ages. establish the effectiveness of spraying Meyco TSL Three test panels were prepared at the 865 directly onto London Clay. Hagerbach testing area in Switzerland: The test was conducted at the bottom of an a) A layer of Masterseal 345, measuring 4 mm existing shaft on freshly excavated material beneath (0.15 in.) thick was sprayed onto Test Panel 1 the overhang of the sprayed concrete shaft lining. with a dry sprayed concrete mix sprayed onto The ambient temperature during the trial was the membrane after it had cured for just over between 13 and 15°C (55 and 59°F). The surface 30 minutes; onto which the TSL was sprayed consisted of London b) A layer of Meyco TSL 865, measuring 5 mm Clay, which had been excavated using a bucket with (0.2 in.) thick was sprayed onto Test Panel teeth. No dressing of the teeth marks had taken place. 2 with a dry sprayed concrete mix sprayed Shotcrete • Fall 2013 51


2013FallShotcreteEMag
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