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Concrete In Australia : March 2009
NEWS LETTERS Sharing knowledge is important I was interested to read the comments of CIA President Tony Kinlay in the previous edition (Vol 34, No 4) concerning the sharing of knowledge and unhelpful attitudes to intellectual property (IP). I have seen other similar sentiments contained in the Summary of Outcomes following the recent Concrete Research Forum in July 2008. Kinlay is right to point out that attitudes can impede the fl ow of benefits from IP. The given example of a firm keeping its product research to itself is a good one of a bad attitude and of uninformed action toward IP. If only such fi rms patented their IP, then full and public disclosure of the product details would be assured for which the patent owner is granted short- term exclusive rights to exploit the fruits of their creativity, free from the ravages of copiers and reverse-engineering. This would also enable avoidance of duplication of effort for other parties interested in the same fi eld and allow them to redirect their attention to new or related applications. I have found that www.ipaustralia.gov. au is a very informative and user-friendly source of information as well as being an entry point to the world of rights, rules and responsibilities of IP. Nevertheless, I believe there is little help available for ideas lacking a productive and useful application but I can’t imagine that would upset too many practising engineers nor the wider community. The legal doctrine of granting short- term exclusive rights in return for public disclosure and the public good goes back to the Industrial Revolution. IP regulation and competitive incentives provide society with a sustainable framework so that better knowledge is valued, resources are invested to generate it, risk of inventive duplication is minimised and the benefits are shared so that all are better off. If the Concrete Institute plans another Concrete Research Forum I would suggest it may be very benefi cial to include input from a suitable IP professional or patent attorney. I also propose to present a paper on this topic at Concrete09. Geoff Fletcher Business Manager Westkon Precast Sunshine, Victoria In regards to the paper on Test methods for assessing durability in the December issue of Concrete in Australia Fred Andrews-Phaedonos makes some very valuable points about the limitations of methods for testing concrete durability. All methods of testing are at risk of falling short of replicating the service environment or providing a value which is an intrinsically reliable indicator of the long-term durability of a concrete mix. The only sound method is to make a full-scale prototype and to expose it to the environment for an extended period. Alternatively, all the concrete could be tested using highly sophisticated MIP techniques. The volume of permeable voids (VPV) test method has these same shortcomings. It does not replicate the service environment and although it provides an empirical measure of the penetrability of the concrete to water, this value does not have a theoretical basis, like say the Darcy coeffi cient of permeability. This generates a serious problem as there is no fundamental link between the test limit and the service requirements other than previous experience. Therefore, if there are changes to the design life, service temperature, exposure to deleterious 4 Concrete in Australia Vol 35 No 1 Test methods for assessing durability agents (eg: chlorides, sulfates and carbonation) or the concrete mix, then the previous experience and the limits may no longer be valid. The designer can specify lower test limits but has no way of knowing if these will adequate or other measures will be needed, such as more cover. Furthermore, the test value only refl ects the physical properties of the concrete but does not address the signifi cant secondary infl uence of the cement binder on buffering the concrete against carbonation or binding chlorides or reducing attack by sulphates. I have specifi ed all the test methods mentioned by the author. On recent projects the NTB 443 and/or NTB 492 chloride migration tests and water penetration testing to BS EN 12390-8 or DIN1048 have been used at the laboratory trial stage. During production, simpler test methods (such as strength or resistivity) are used for assessing the quality of the concrete. The limits for these simpler tests are derived from the laboratory trials. The chloride migration and water penetration values from the laboratory testing can, with care, be used to verify the assumptions for chloride diffusion coeffi cient and coeffi cient of water permeability used in the durability design. The differences between laboratory samples and a real structure must be allowed for when using the test data. The author correctly points out that mass water movement must be allowed for in the design. However, for 100 year life structures subject to tidal exposure, the water absorption, although fast, will only account for movement in the outer 20mm of the concrete with the remainder being down to diffusion. The VPV test does appear to provide a reliable indicator of one of the most signifi cant factors in concrete durability, its penetrability to water. An alternative to the author’s proposal is to use test methods like NTB 492 and DIN 1048 for mix development and use the VPV test for quality control. As data is accumulated it might prove possible to rely wholly on meeting VPV limits for similar types of project. Monitoring the performance of structures in the field is vital to check that there is a realistic and rational basis for predicting long-term durability and also demonstrating that the VPV limits are appropriate and effective. Don Wimpenny Halcrow wimpennyde@Halcrow.com