Located in the outskirts of Lhasa (the capital of Tibet) at an altitude of more than 4000 meters above sea level, this cement clinker silo is a cylindrical, reinforced concrete structure measuring 45m high. An annual maintenance service discovered extensive cracks and severe concrete spalling within the clinker's inner walls. Some of the beams have been badly damaged and even fractured. In several areas, the concrete cover had already spalled to such depth that the rebars were exposed. The damage to the concrete cover was caused by the highly abrasive effect of the clinker during discharge operations while the constant impact force on the inner concrete walls and beams was the cause of the extensive structural cracks and fracture in some beams. Moreover, the operating temperature in the silo is about 150 deg C, a high temperature dry heat environment which accelerated the concrete spalling process. A strengthening scheme using TYFO?SEH 51 and TYFO?T, a high temperature resistant epoxy was adopted to strengthen the damaged beams. The TYFO? T was proposed in view of the constant high operating temperature of 150 deg C. Since the structural members were constantly exposed to recurring high impact and abrasive actions, a mixture of high temperature resistant TYFO? T and silicon carbide powder was used as an external protective layer. Despite the harsh and unforgiving environment, the project took only one month to complete and the silo resumed production in January 2009 and has been incident-free to date.
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