Physical and Mechanical Properties Performance between Untreated and Treated with CCA Treatment at Different Age Groups of Fast-Growing Acacia Hybrid of Sarawak

Round 1

Reviewer 1 Report

The results of the research bring new information enhancing the knowledge of scientists involved in wood protection. Considering the number of samples and laboratory tests performed, the reviewer is full of appreciation for the volume of the work done. In addition to its unquestionable qualities, the submitted work requires minor additions:

1.      On what basis was the concentration of the preservative agent and the technological parameters of the process selected?

2.      Under what conditions (temperature, relative humidity) were the samples conditioned before testing?

3.      Did the authors evaluate the effectiveness of the treatment (e.g. on the basis of retention and depth of penetration into the wood). Biological tests to determine the effectiveness of wood preservation may also be a sure way to determine the quality of preservation. Have such tests been conducted?

4.      How many samples were used in the strength tests?

5.      The figures show: 7 - year-old , 10- year-old, 13-year-old. On the other hand, in the axis title it is: Age (Year old). It is proposed to remove year old in the axis title: Age (Year old) or on the axis: 7 - year-old , 10 - year-old, 13 -year-old. On the Figure 6 on the Y axis there is moiscture , should be moisture.

6.      Authors should correct units on the Y axis on the Figures 7 and 9.

7.      Table 6 with the explanation in the previous section should be given (not in the Conclusions).

 

Author Response

Please see the attachment. Thank you.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors,

Extensive research was conducted with important insights into treated (CCA wood) and untreated physical and mechanical properties. Moreover, the article provides information on this fast-growing Acacia hybrid in timber engineering. However, several remarks are noted.

 

1.      The title indicates that treatment was performed yet does not contain the type of treatment (CCA treatment in your case).

2.      Line 24: treatment

3.      Line 27: … to the grain …

4.      Line 50: colour

5.      Line 58: '' Acacia hybrid also showed the ability to improve soil properties in both physical and chemical.'' It would be acceptable to note which properties since the authors mentioned it had improved species with fast-growing time (it would be worth information for readers in the field of forestry)

6.      Line 77: ''Due to the environmental impact of timber engineering application, understanding the treated timber for durability is very important.'' Since the authors explored the properties of CCA-treated and untreated wood, the suggestion would be to perform (for future examination) an accelerated weathering test, leaching and decay resistance test.

7.      Line 376: the grain (correct throughout the text)

8.      Did the solution penetrate through the entire cross-section? Is it measured or pure an assumption?

9.      Results showed that 7-year old wood has 0,503 g/cm³, 10-year old has 0,479 g/cm³ and 13-year old has 0,507 g/cm³ (data for untreated wood). According to data from mechanical properties, you concluded that 10-year-old wood has more heartwood tissue than 7-year-old and 13-year-old wood. How do you explain that 10-year-old wood has the highest heartwood tissue presence and lowest density? It would be great to perform more examination of anatomical features to upgrade all explanation

10.  Line 283: Examination showed that the density of 7-year-old wood remained unchanged. How do you explain this?

11.  Line 556: ''It is recommended that air-dried 10-year-old Acacia hybrid is the most suitable with consistent physical properties value and mechanical strength value in shear parallel to grain at the tangential direction, cleavage at tangential direction and tension when treated with Copper Chrome Arsenic (CCA) treatment.'' Is this influenced due to high heartwood tissue presence in 10-year-old wood?

12.  Have you considered expressing properties (density and mechanical properties) at 12% moisture content?

 

13.  In summary, the investigation is based on CCA treatment, which, as you mentioned, is widely used in Malaysia's timber industry. CCA treatment is used as a wood preservative to make it resistant to attack by termites and fungi that cause decay. The latest research aiming that individual components of CCA (As and Cr) pose severe human health problems, so their removal from the environment should be promoted. Moreover, evidence suggests that arsenic, chromium and copper levels in surface soils, close do CCA treated wood may surpass permitted levels and induce concerns about human and environmental health. The arsenic that migrates to the wood's surface and leach out is a well-known human carcinogen related to nervous system damage and congenital disabilities. Have you thought about Alkaline Copper Quaternary (ACQ) (also known as Copper Azole (CBA)) treatment? Small amounts of copper and quat leach out, but nothing in ACQ is considered hazardous. Many results showed that ACQ-treated wood is non–toxic in terms of dermal and oral exposures.

Author Response

Please see the attachment. Thank you.

Author Response File: Author Response.pdf