ENVIRONMENTAL EFFECTS ON THE BEHAVIOUR OF WRAPPED CONCRETE CYLINDERS

摘要

Long term exposure to harsh environments deteriorates concrete and the need for repair or rehabilitation is evident. In order for a new repair material to become accepted it must be evaluated for durability in these harsh environments. This paper is focussed upon rehabilitation of reinforced concrete columns and compares the effectiveness of glass fibre and carbon fibre wraps against a polyurethane/ polyurea (Rockguard) coating that is currently used in the mining industry. Over 200 concrete cylinders, 150mm x 300mm in size, were exposed to freeze thaw and wet dry conditions in salt water, fresh water, and air. Cylinders were either wrapped with glass fibre, carbon fibre or Rockguard. Compression tests to failure were conducted after exposure periods of 50, 100, and 250 cycles. The performance of the columns was evaluated by comparing their stress-strain behaviour and their ultimate load capacity. To compare laboratory and field conditions, six reinforced circular concrete columns (800mm high x 200mm diameter) with spiral reinforcement were placed in Lake Ontario near Kingston, Ontario. Two of these columns were coated with glass fibre, two with Rockguard, and two were left uncoated. During this study, the columns were exposed to wave action, ultraviolet light, biotic life, ice and freezing. Unfortunately the column results are not available at the time of writing of the paper.