Evaluation of Selected Accelerated Above-Ground Durability Testing Methods for Wood after Ten Years Exposure
Round 1
Reviewer 1 Report
I have some concerns about the experimental design "problems" that the authors detected over the 10 years of study, namely the results of ground proximity tests of exposure: if the samples' conditions in the beggining and at the end of the study were not the same (meaning that they have fallen to the ground and the shade-cloth used to protect the samples just desapeared) the cannot take 100% precise results).
I believe this is my major concern. Mainly because you say that these results give the most useful results, which I believe. But I think that would be true if the samples either stayed in the ground at the beggining or if they were stand up without fallen.
Author Response
In the ground-proximity test, samples were not fallen to the ground. Samples were on concrete paving slabs with weed-mat underneath as per the original installation.
Previous wording was somewhat confusing hence changes are now made to make it clearer. It was the imbedded test where samples were fallen to the ground but in this manuscript, we have not included embedded test. We have mentioned it in 2.2 Assessment method (line 226-227 in the track changed version). If its confusing we can take it out.
Reviewer 2 Report
After a comprehensive introduction and well-presented methodology, I am disappointed with the chapters: results, discussion, and conclusions.
In results chapter is the lack of reference to conducted statistical tests.
Authors in the methodology described applying quantitative tests, whereas the applied description of the process of the disintegration is a quality feature. Admittedly described statistical methods allow the assessment of the influence of quality features but in the paper appears no one information what features were being measured and which had a statistically significant influence.
The lack of the value of statistics of Fisher, Student, and the calculated probability level considerably lowered the value of the work.
The discussion has a summary description form because doesn't constitute the confrontation with the results other authors.
Conclusions are ineligible because haven't comm from statistical tests.
Author Response
Response: Reviewer’s comments related to Statistical analysis and their references in Results, Discussion and conclusions sections.
We agree that better statistical analysis and predication model can be applied to confirm the results. Differences in test and treatment effects were confirmed by a linear model. Which is summarised in Table 3 as Supplementary material. Further, Statistical analysis was undertaken using R. Mixed effects models used the lme4 package. Decay scores in 2017 were predicted from a mixed-effects regression.
In the result section following part is included..
decay scores in 2017 were predicted from a mixed-effects regression (conditional on treatment as a random effect; R2 =0.68, RMSE = 2.08, Figure 7 – Supplementary material). The model showed a statistically significant overall relationship between decay scores in 2011 and 2017 (Coefficient= 0.14+-0.07, d.f =345.7, t=2.038, P=0.042). Fixed effects of test type showed that flat Panel and Ground Proximity test had significantly lower scores in 2017 than other tests (d.f =342.2, t=3.313, P=0.001 and d.f =342.1, t=12.890, P<0.001 respectively).
Figure 7 is included in supplementary material.
In the abstract and conclusion sections, summary of statistical analysis is included (line 23-26 in the track changed version and 397-398)
Reviewer 3 Report
The manuscript contains valuable results that can be useful worldwide. Tedious, long-lasting experiments have been done. It’s a good paper, but some editions are advised.
Title: I’d rather avoid the word „review” in title as it suggests misleading character of the paper. “Comparison”, “evaluation” etc. would be better.
Abstract is not informative enough. Expressions like “similar” or “different” are not enough. Details with experimental data values should be added. I also suggest do not use abbreviations such as “CCA” in abstract. Also, a clear indication which test is most suitable, reliable and useful should be added.
Introduction is lacking some more information on the existing outdoor exposure testing methods. It would be beneficial if some advantages and disadvantages were described.
Line 55-56: “This manuscript reviews the condition of samples in five test methods to determine whether relative durability results after four years would still be valid after ten years exposure.”. I suggest re-phrase the sentence as is clear in meaning and does not reflect the content of the paper and also avoid use of “review” word. Please describe it more precisely.
Line 70-72: As the stake, embedded and rot box specimens are not discussed in this paper. I suggest not mention them at all.
Line 79: “five rows with about 10 mm between samples on all sides”. Do you mean “10-mm gaps between…”?
Line 134:” AWPC (2015)” – wrong citation. Should be [26].
Line 136-138: Sentence “These racks were constructed from treated pine framing and had been in use for many years hence the framing timber contained some decay when this test was installed” is not meaningful. I suggest delete.
Lines 146-147: Sentence “The underlying rack was more than 30 years old and some frame components contained decay when the test was installed.” is not necessary in the caption.
Lines 154-160: Description of the solutions used is not enough. If they were commercial give a trade name. Resolve all acronyms used. “Light organic solvent” – it is not precise. If commercial - give trade name, if self-prepared solution - give solvent.
Line 172, 176, 179: “vacuum -95 kPa”. I’d rather express/add pressure in bar or Torr instead.
There is no information on how “uptake” was calculated. Was it true preservative retention or density gain in wet state? Details in methodology have to be added.
Line 178: ‘LOSP’ needs to be resolved.
Table 1 – what GL stands for? Explain what 1/4 stands for?
Figs. 5&6 – I suggest to indicate (e.g. with arrows) which samples are controls, which were upturned etc. So that the caption corresponds better with the figure.
I suggest minor revision.
Author Response
The manuscript contains valuable results that can be useful worldwide. Tedious, long-lasting experiments have been done. It’s a good paper, but some editions are advised.
Title: I’d rather avoid the word „review” in title as it suggests misleading character of the paper. “Comparison”, “evaluation” etc. would be better.
Response: The word ‘review’ has been taken out from the title and as suggested has been replaced with ‘evaluation’
Abstract is not informative enough. Expressions like “similar” or “different” are not enough. Details with experimental data values should be added. I also suggest do not use abbreviations such as “CCA” in abstract. Also, a clear indication which test is most suitable, reliable and useful should be added.
Response: Amendments made as suggested. Wording such as ‘similar’ are taken out. Use of regression model for prediction is included. Below is the amended abstract, (red highlighted areas showing changes made).
Traditional benchmark wood durability testing methods such as stake tests take many years to give conclusive results and in-ground tests do not always indicate the efficacy of preservatives in above-ground situations. To find test methods that would shorten the time required for wood evaluation for above ground end uses, a series of different types of accelerated durability tests were set up. Five types of test; ground proximity, two types of decking, flat panels and double layer, were reassessed after ten years to determine whether the decay rankings given to the various types of preservative had changed over the extended exposure period. Exposure conditions varied between tests with ground proximity being close to ground, double layer test with very wet conditions while raised decking and flat panel tests were relatively dry. In all of these tests the preservative retention was 25% of the normal H3 retention. The results indicated that the ground proximity tests gave the fastest and most reliable results. Flat panels contained the next highest decay rates, followed by ground-level decking, double layer and raised decking. The evaluation and comparison of these five test methods after ten years field exposure confirmed the trend and relative decay rate that was observed at four-year exposure. Use of regression model for prediction showed a statistically significant overall relationship between decay scores in 2011 and 2017 (Coefficient= 0.14+-0.07, d.f. = 345.7, t=2.038, P=0.042). When resistance to decay was compared between preservatives, copper-chrome arsenate (CCA) treated pine and naturally durable spotted gum samples were in better conditions than pine treated with any of the other preservatives.
Introduction is lacking some more information on the existing outdoor exposure testing methods. It would be beneficial if some advantages and disadvantages were described.
Response: Further paragraph is added related to existing outdoor exposure methods with some advantages and disadvantages.
Line no. 51-56 in the track changed version (as below)
Each method has advantages and disadvantages [12], for example, it was recognized in our previous work that if in the above ground test method such as ‘Peg test’ [22] the specimens are too small it dries-out very quickly which can have adverse effect on fungal establishment and growth and can delay the test results. However, the advantages of ‘Peg test’ is that it is simple and easy to set up and number of replicates can easily be increased so better statistical results can be produced.
Line 55-56: “This manuscript reviews the condition of samples in five test methods to determine whether relative durability results after four years would still be valid after ten years exposure.”. I suggest re-phrase the sentence as is clear in meaning and does not reflect the content of the paper and also avoid use of “review” word. Please describe it more precisely.
Response: Sentence is changed. Now it reads as below;
This manuscript evaluates and compares the condition of samples and relative durability ratings in five above-ground decay test methods after exposure periods of four and ten years. This was to determine which method gave the fastest results and whether rankings after four years remained the same after ten years.
Line 70-72: As the stake, embedded and rot box specimens are not discussed in this paper. I suggest not mention them at all.
Response: Agree and changes made as suggested.
Line 79: “five rows with about 10 mm between samples on all sides”. Do you mean “10-mm gaps between…”?
Response: Yes, word ‘gaps’ included.
Line 134:” AWPC (2015)” – wrong citation. Should be [26].
Response: Yes, agree. Changes made.
Line 136-138: Sentence “These racks were constructed from treated pine framing and had been in use for many years hence the framing timber contained some decay when this test was installed” is not meaningful. I suggest delete.
Response: Agree, deleted as suggested.
Lines 146-147: Sentence “The underlying rack was more than 30 years old and some frame components contained decay when the test was installed.” is not necessary in the caption.
Response: Agree, deleted as suggested.
Lines 154-160: Description of the solutions used is not enough. If they were commercial give a trade name. Resolve all acronyms used. “Light organic solvent” – it is not precise. If commercial - give trade name, if self-prepared solution - give solvent.
Response: More information is provided as below (Line number 169-185 in the track changed version)
- Alkaline copper quaternary (ACQ), supplied by Osmose Ltd. as copper ammonium carbonate (CAC) and Didecyldimethylammonium chloride (DDAC). An aliquot of 360 ml of CAC and 227 ml of DDAC were added to water to make up 100 litres of a preservative solution containing 0.055% active ingredients (CAC + DDAC).
- Copper-chrome arsenate (CCA), Tanalith O oxide supplied by Arch Wood Protection, Ltd. was shown by Inductively coupled plasma mass spectrometry(ICP-MS) analysis to contain 9.2% Cu, 15.2% Cr and 12.4 As. Twenty litres of solution was made up using water and 32.27 g of Tanalith O to give a treating solution containing 36.8% m/m total active ingredients.
- Tebuconazole/propiconazole LOSP was Vacsol Azure supplied by Arch Wood protection Ltd. and shown by analysis to contain 0.048% (w/v) tebuconazole, 0.047% (w/v) propiconazole and 0.33% (w/v) permethrin i.e., it contained 9.5 g/litre total azoles.
- Tributyl tin naphthenate Lifewood H3 (235WR) supplied by Osmose Ltd. contained 1.1-1.2% m/v tin, 0-2% permethrin, 0-5% dichlofluanide and > 90% white spirits. The treatment solution supplied contained 0.38% m/v tin. (this is 25% of the H3 requirement in Australia but 50% of the H3.1 requirement in New Zealand)
- The high flashpoint kerosene was supplied by Arch Wood Protection, as Shell Mexcut 8 with a specific gravity of 0.8 at 15o C and a flashpoint of 78o
Line 172, 176, 179: “vacuum -95 kPa”. I’d rather express/add pressure in bar or Torr instead.
Response: bar is added.
There is no information on how “uptake” was calculated. Was it true preservative retention or density gain in wet state? Details in methodology have to be added.
Response: Information is added.
Samples were weighed immediately before and after treatment. The surface of those treated with water-based preservatives was wiped with absorbent paper to remove surface liquid before being weighed after treatment. Preservative uptake was calculated by dividing the sample weight gain during treatment by the saturated volume of the sample and expressed as litres/cubic metre.
Line 178: ‘LOSP’ needs to be resolved.
Response: Further information is added where LOSP explanation is needed
Tributyl tin naphthenate Lifewood H3 (235WR) supplied by Osmose Ltd. contained 1.1-1.2% m/v tin, 0-2% permethrin, 0-5% dichlofluanide and > 90% white spirits. The treatment solution supplied contained 0.38% m/v tin.
The high flashpoint kerosene was supplied by Arch Wood Protection, as Shell Mexcut 8 with a specific gravity of 0.8 at 15o C and a flashpoint of 78o C.
Table 1 – what GL stands for? Explain what 1/4 stands for?
Response: GL is “ground level”, now written in full.
¼ is explained as footnote of the tables. It is ‘Preservative retentions were one quarter of that required in New Zealand for treatment to the H3 specification”.
Figs. 5&6 – I suggest to indicate (e.g. with arrows) which samples are controls, which were upturned etc. So that the caption corresponds better with the figure.
Response: Arrows and asterisks included.
