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Concrete In Australia : December 2010
Concrete in Australia Vol 36 No 4 61 no evidence of any cracking in the concrete. More significantly there is no evidence of moisture penetration into the interior of the building. us the implication of this case study is that a regular maintenance program would have saved money over the first 40 years of the life of the building (1965--2005). Applying a coating to the concrete in 1970 and then at 15 year intervals would have cost in the region of £80,000 (at 1992 prices). This is based on £47,000 for the first treatment (1970) and £33,000 for each re-treatment (1985 and 2000). Table 6 details the notional costs of the preventive works approach and expresses these as a percentage of the 1992 repair cost (£197,868). It will be seen that it is estimated that these two preventive treatments would have amounted to some 57% of the 1992 repair cost. ese results are presented graphically in Figure 11. Figure 11 illustrates the notional costs of a preventive works approach and expresses these as a percentage of the 1992 repair cost. It is estimated that the three preventive treatments would have amounted to some 57% of the 1992 repair cost. us over the first 40 years of the life of the building a preventive maintenance approach might have delivered a significant cost saving in excess of 40%, relative to the repair work which had been required under the reactive approach adopted. Furthermore, there might have been important other advantages including less disruption to users and better protection of the value of the asset. 6.0 SOME FREQUENTLY ASKED QUESTIONS (FAQS) Q1: How do I choose a suitable professional technical team to support me as the owner? A1: Selection should be on the basis of professional and technical competence combined with appropriate previous experience and track record. It should not be solely on the basis of fee competition or the lowest initial cost, as this often does not provide best value. Q2: What kind of obligations and responsibilities do I have as an owner? A2: Legal obligations vary from country to country and possibly even within a single country, depending whether there are local statutes/ordinances for particular types of structures. Inappropriate action could make an owner liable to financial penalties or expose them to censure by shareholders or others. Q3: What are the common forms of deterioration of concrete structures? A3: The most common problem for structural concrete is corrosion of carbon steel reinforcement. Generally corrosion will eventually produce a brown staining on parts of the concrete surface, cracking and finally spalling of the concrete surface. ough less common concrete itself can deteriorate; through attack by sulfate, by alkali- silica reaction or by physical actions such as freeze-thaw or impact. Q4: What role do inspections and assessments have in managing concrete structures? A4: Inspections and assessments should assist an owner in identifying and managing health and safety issues, financial risks and maximising the benefits associated with the ownership of an asset. A proactive approach to management should enable early identification of problems; potentially enabling early preventive action to be taken to minimise the overall through life cost of ownership. Q5: What problems do cracking and spalling of concrete cause? A5: Cracking and spalling damage the concrete cover layer, potentially creating loose pieces of concrete which may pose a hazard of falling debris and the risk of injury to the public. Cracking, delamination and spalling of cover concrete increase the exposure of the reinforcement, enhancing the rate of corrosion and associated damage. Figure 10. The Ashby Building after repair.  e 1992 repair cost is taken to be the total cost of the works undertaken less work to window frames and internal redecorating (refer Table 5).