1.12 MATERIALS TESTING

1. 1.12 MATERIALS TESTING • 1.12.1 The Experiments • 1.12.2 Defining the general objectives • 1.12.3 Reviewing previous work • 1.12.4 Resources and time limits • 1.12.5 Choosing a method • 1.12.6 The null hypothesis • 1.12.7 The detailed method

2. The need for new experiments • There are often no methods for calculating material properties.          • Materials are continually changing. (e.g. cements) • New materials (e.g. pultruded plastics for beams) must be tested. • Unexpected problems (e.g. delayed ettringite formation) occur with some materials and must be researched. • There are generally no complete answers from these experiments.

3. 1.12 MATERIALS TESTING • 1.12.1 The Experiments • 1.12.2 Defining the general objectives • 1.12.3 Reviewing previous work • 1.12.4 Resources and time limits • 1.12.5 Choosing a method • 1.12.6 The null hypothesis • 1.12.7 The detailed method

4. Defining Objectives • It is quite rare to carry out an experiment simply to see if one material is adequate for an application (radioactive waste disposal research is an exception to this). • In general durability experiments are aimed at improving a material or method. • Thus the aim is to see if the new method works better than the old one.

5. Possible objectives • “will this paint last longer than the usual one” • “will this change to the concrete mix improve its durability”. • “will this change to the concrete mix make its susceptibility to sulphate attack more sensitive to poor curing” (this requires multi-variate analysis)

6. 1.12 MATERIALS TESTING • 1.12.1 The Experiments • 1.12.2 Defining the general objectives • 1.12.3 Reviewing previous work • 1.12.4 Resources and time limits • 1.12.5 Choosing a method • 1.12.6 The null hypothesis • 1.12.7 The detailed method

7. Where to find references • Library index systems. • References from other documents. • Commercial data-bases which are available on line. • Many organisations (e.g. the British Cement Association) have large data bases on which they will do keyword searches (for a fee). • If you have one paper on the subject a system called the citation index may be used to find others which have cited it as a reference. (science only) • The internet... Google Scholar

8. TYPES OF REFERENCES • Journal Papers • Conference Papers • Light Weight Journals • Company Literature • Books • Web sites

9. Journal Papers • These are the best because they are peer reviewed by a technical committee who are experts in the subject. • Note, however, that Universities and many other organisations never carry out any internal review • Any academic is free to send off anything he wants to a journal. Journals are under pressure to publish easily readable papers. • If a journal rejects a paper the authors will often send it to other journals until they find one that will accept it.

10. JournalPublicationDates

11. The future of Journal Publishing??Coventry University has an “Athens” subscription

12. Journal Rankings

13. Changes in journal publishing • Worldwide there are 24,000 journals publishing 1.3 M papers per year. • 50 M papers already published. The bulk have now been scanned. • New journals being set up using “open source – author pays” model. • Great emphasis on citations. Can be tracked with ISI or Google Scholar.

14. TYPES OF REFERENCES • Journal Papers • Conference Papers • Light Weight Journals • Company Literature • Books • Web sites

15. Conference Papers • The review process for these is often minimal. • Authors pay to attend conferences. • Conference proceedings are normally published in book form. • There is often a "supplementary volume" which has even less review.

16. TYPES OF REFERENCES • Journal Papers • Conference Papers • Light Weight Journals e.g. New Civil Engineer. These should be treated with caution but they will often give you references to work from • Company LiteratureThis is basically advertising and is not externally reviewed • Books • Web sites

17. CompanyLiterature

18. TYPES OF REFERENCES • Journal Papers • Conference Papers • Light Weight Journals • Company Literature • Books Text books are normally based on published research. They often have a few errors in them. Some books are more like research monographs and the contents may be new and unchecked • Web sites: Wikipedia is often criticised as being unreliable but is probably as good as most other sources.

19. References • The essential point is never to rely on references from a single source, always look for independent confirmation of results. • You must remember that most researchers are under considerable commercial pressure to publish papers and, in particular, results that will help them to obtain funding.

20. 1.12 MATERIALS TESTING • 1.12.1 The Experiments • 1.12.2 Defining the general objectives • 1.12.3 Reviewing previous work • 1.12.4 Resources and time limits • 1.12.5 Choosing a method • 1.12.6 The null hypothesis • 1.12.7 The detailed method

21. Resources and time limits • Note that many materials are like concrete in that they take several weeks to achieve their design properties. This time must be allowed for.

22. 1.12 MATERIALS TESTING • 1.12.1 The Experiments • 1.12.2 Defining the general objectives • 1.12.3 Reviewing previous work • 1.12.4 Resources and time limits • 1.12.5 Choosing a method • 1.12.6 The null hypothesis • 1.12.7 The detailed method

23. Choosing a method The three objectives are: • 1. Make it realistic • 2. Make it fast • 3. Make it cheap These three are conflicting.

24. The samples • In a real construction environment materials are never in optimum condition.. • The difficulties with simulating site conditions are that all sites are different and that all scientific experiments must be designed to be repeatable. • One solution is to try to simulate both best and worst conditions. • The geometry of the sample may affect durability.

25. The Environment. • In general real exposure experiments are not very useful because they are too slow. • Deterioration may be accelerated with, for example, heat, pressure, applied voltages, or pre-contaminating the samples. • Each of these methods must be used with care. Heat slows down sulphate attack. Mixing chlorides into wet concrete makes it less permeable.

26. 1.12 MATERIALS TESTING • 1.12.1 The Experiments • 1.12.2 Defining the general objectives • 1.12.3 Reviewing previous work • 1.12.4 Resources and time limits • 1.12.5 Choosing a method • 1.12.6 The null hypothesis • 1.12.7 The detailed method

27. The null hypothesis • This is a statement such as "treatment X makes no difference to the durability of this product". The experimental data are then used to show that there is a probability of less than 5% of this being true.

28. 1.12 MATERIALS TESTING • 1.12.1 The Experiments • 1.12.2 Defining the general objectives • 1.12.3 Reviewing previous work • 1.12.4 Resources and time limits • 1.12.5 Choosing a method • 1.12.6 The null hypothesis • 1.12.7 The detailed method

29. Multivariate or Bi-variate • Bi-variate means change just one variable and measure another - for example vary the w/c ratio and measure the strength. • Multivariate experiments involve changing several variables and testing whether they interact, i.e. whether changing one makes the result more sensitive to changes in another. They are difficult to analyse but can be very powerful. Analysis of Variance (ANOVA) gives a measure of the relationship between 3 or more columns on a spreadsheet

30. Exercises on Published ACI Paper • How many samples were cast? Was this enough? • Top right of p.301 • What is 14M NaOH? • Does it make sense to say “tap water was used to mimic field conditions”? • P.303 top of left column. What are ksi? • How old were the samples when tested? • Which points in fig 2 represent new results? • Does fig 4 communicate anything? • Does the paper tell you whether GPC is better or worse than normal concrete? • In the references, find a journal paper, a conference paper, a book and a report.