ABSTRACT
Radical Concrete Technology. Edited by R K Dhir and P C Hewlett. Published in 1996 by E & FN Spon, 2-6 Boundary Row, London SE1 8HN, UK. ISBN 0 419 21480 1. ABSTRACT. Centrifugal concrete poles are used to a great extent by the Public Power Corporation (P.P.C.) to support overhead distribution lines. A considerable number of these poles have shown signs of serious distress with a direct bearing on their strength. A serious effort has been undertaken by PPC to survey, record and classify the damage of approximately 1500 concrete poles in various parts of Greece. The damages recorded were mainly longitudinal cracks and spaling of concrete, as well as corrosion of the longitudinal steel reinforcement. From the recorded damages, it became clear that by far the overwhelming majority of cracking was associated with cracks parallel to reinforcement (80% of the damages). It is worth noting that more than half of these, were located at the seams of the molding forms. Below these cracks, the steel reinforcement was corroded. Laboratory tests carried out on 50 poles removed from the network, and on samples taken from 70 poles still in use have shown that cracks were always associated with carbonation of concrete and corrosion of reinforcement. In areas adjacent to sea, the contents in Cl−, at the locations of cracks, were critical. The results of this study helped in formulating the new P.P.C. specifications for the manufacturing of centrifugal poles. The new specification has encompassed our present day knowledge regarding durability (cover thickness, requirements for a denser and less permeable concrete) and incorporated improvements such as: increase of spiral reinforcement, controlled methods of accellerated curing. Keywords: Concrete, Poles, Reinforcement, Corrosion, Cracks. Dr Antonis Sakellariou is in charge, of the Concrete Laboratory, at the PPC Testing, Research and Standards Center (T.R.S.’C./PPC), Athens Greece. His main research interests include properties of concrete regarding durability.
