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ISSN : 1598-5504(Print)
ISSN : 2383-8272(Online)
Journal of Agriculture & Life Science Vol.53 No.3 pp.1-6
DOI : https://doi.org/10.14397/jals.2019.53.3.1

# Relationship between Physical and Mechanical Properties and Node Height in Major Three Species of Korean Bamboo

Kyung Rok Won1, Kwang Soo Lee2, Su Young Jung2, Byung Oh Yoo2, Han Min Park1,3, Hee Seop Byeon1,3*
1Dept. of Environmental Materials Science, College of Agriculture & Life Science, Gyeongsang National University, Jinju, 52828, Korea
2Forest Biomaterials Research Center, Jinju, 52817, Korea
3Institute of Agriculture & Life Science, Gyeongsang National University, Jinju, 52828, Korea
Corresponding author: Hee Seop Byeon Tel: +82-55-772-1861 Fax: +82-55-772-1869 E-mail: hsbyeon@gnu.ac.kr
November 26, 2018 January 10, 2019 February 7, 2019

## Abstract

Bamboo forests are fast-growing, renewable resources, and their carbon sequestration potential has attracted increasing attention. Although bamboo can be used for many purposes, bamboo forests in Korea represent a generally underutilized resource. The main objective here was to perform an assessment of the physical and mechanical characteristics of different species of bamboo found in Korea. The main species of domestic bamboo are Phyllostachys bambusoides, P. pubescens, and P. nigra; we measured the air-dried density for each of the species, with obtained values of 0.89 g/cm2, 0.79 g/cm2, and 0.83 g/cm2, respectively, giving the density order of P. bambusoides > P. pubescens > P. nigra, with P. bambusoides having the highest density. We then measured the compressive strength of each species, which were 802.84 kgf/cm2, 624.69 kgf/cm2, and 743.77 kgf/cm2, respectively, in the order of P. bambusoides > P. pubescens > P. nigra, with P. bambusoides having the highest compressive strength. Volume and maximum load decreased with increasing node height in the three bamboo species, whereas air-dried density and compressive strength increased. Our results thus add to the pool of essential knowledge about Korean bamboo species, and consequently to the development of a potentially valuable domestic resource in Korea.

## 초록

National Institute of Forest Science

## Introduction

Global warming causes changes in various environments, notably with respect to plant distributions (Jung et al., 2014). As a result of recent climate change, bamboo is expected to expand northward in areas confined to a limited expanse of southern Korea, and attract broad attention as a useful forest resource that is fast-growing and features higher rates of carbon storage than that by many other types of vegetation.

Bamboo has a higher specific compressive strength than that of wood, brick, or concrete, and has a specific tensile strength similar to that of steel. As bamboo grows, various structural forms are possible by transforming bamboo stalks during developmental stages; for example, square sections of bamboo can be formed by compressing growing stalks into the shape of a square, and arches can be used for various purposes as they can be formed into desired shapes as bamboo grows. Such characteristics make bamboo a potentially useful structural material (Kute et al., 2013).

Bamboo has long been used in structures in other countries; in China, for instance, buildings up to six floors in height can be constructed with bamboo, and it is also used in high-rise buildings in Hong Kong. In Japan, it is used in architecture, interior designs, and fencing. In terms of the development of bamboo use in Korea, major efforts have been extended toward effective morphological deformation and use as a woody plate material for such purposes as OSB, MDF, and building materials (Roh, 2007;Lee et al., 2009;Park & Park, 2012).

However, domestic bamboo is still infrequently used in construction in Korea, and many Korean bamboo forests have been transformed into bushlands because of extensive deforestation (Yoo et al., 2017). However, expansion of the use of domestic bamboo will first require basic research on the developmental patterns of the primary bamboo species occurring in Korea, and how the physical and mechanical properties of each species vary with stalk height. Recently, Jeon et al. (2018) reported that 2-year-old or older bamboo are mature and structurally stable within their first year.

Bamboo forests mainly grow in the southern part of the Korean peninsula, with native bamboo composing 5 genera and 19 species. The primary purpose of this study was to assess and compare the physical properties of 3-year-old bamboo trees of three species and to determine how these properties may differ with bamboo height.

## Materials and Methods

### 1 Materials

Phyllostachys bambusoides Siebold & Zucc., Phyllostachys pubescens Mazel ex Lehaie, and Phyllostachys nigra var. Henonis were sampled in the southern experimental forests maintained by the National Institute Forest of Science, Korea Forest Service (Jinju, Gyeongsangnam-18, Gyeongsangnam-do, Gajwadong, 120-1). Whole stalks of these bamboo species were selected, taking into consideration and bamboo shoot. And same three-year-old bamboo was used. In addition, for the purposes of making comparisons between the material characteristics of each species, three samples were taken from a separate site with standardized conditions to minimize any differences in aeration among the sampling sites. All data were analyzed using SPSS software (Version 21, IBM, Corp, USA), and Duncan’s dispersion test was performed at a 0.05 significance level by repeated measures analysis.

### 2 Specimen preparation

Specimens were cut at a height of 40 mm, which preliminary tests of compressive strength indicated was the most stable height. A total of 243 specimens were collected for comparisons of material properties. For comparisons of the material properties based on stalk height, 567 specimens were prepared for each of the three species. Table 1

### 3 Physical characteristics

Air-dried density was measured in accordance with KS F 2198 (method of measuring the density and specific gravity of wood) guidelines of the Korean Industrial Standard (KS) following humidity conditioning for 8 weeks in a constant temperature and humidity chamber (temperature 20±1℃, humidity 65±3%) (Korean Standards Association. 2016). Sample volume and weight were measured, and sample density was determined by the equation (1).

$ρ w = m 0 ( 3.14 × a w × 2 × l w ) − ( 3.14 × b w × 2 × l w ) = m 0 V w$
(1)

• m0: air-dried weight of specimen

• aw, bw, lw: radius of specimen, radius minus thickness and length in a state of air-dried specimen

• VW: air-dried volume of specimen

### 4 Mechanical characteristics

Specimens used in the compressive strength performance tests consisted of bamboo that had been seasoned and conditioned in the temperature and humidity chamber (temperature 20±1℃, humidity 65±2%) in accordance with KS F 2206 (wood compression test method) protocols of the Korean Wood Specification (KS) guidelines(Korean Standards Association, 2014). Compressive strength was tested in parallel with fiber direction; cross-sections of the test specimens were positioned vertically between load blocks and evaluated using a universal testing machine (Shimadzu, model EHF-ED10-20L) at a crosshead speed of 1.0 mm/min. Tests were carried out so that the load was applied to the cross-section, and compressive strength (σcmax) in the fiber direction was defined as the maximum load. Measurements were calculated using equation (2).

$σ c m a x = P max A$
(2)

• A: Cross-section area

## Results and Discussion

### 1 Wood material characteristics by bamboo species

#### 1.1 Physical properties

Measurements and comparisons of the density of the domestic bamboo species P. bambusoides, P. pubescens, and P. nigra are shown in Table 2. The major domestic bamboo species were divided into three groups, ie, P. bambusoides, P. pubescen, and P. nigra. The average air-dried density of P. bambusoides, P. pubescens, and P. nigra were 0.89 g/cm2, 0.79 g/cm2, and 0.83 g/cm2, respectively, and root density was the highest in P. bambusoides.

#### 1.2 Mechanical properties

Measurements and comparisons of the compressive strength properties of the domestic bamboo species P. bambusoides, P. pubescens, and P. nigra are shown in Table 3. The major domestic bamboo species were divided into three groups, ie, P. bambusoides, P. pubescen, and P. nigra. The average compressive strength properties of P. bambusoides, P. pubescens, and P. nigra were 802.84 kgf/cm2, 624.69 kgf/cm2, and 743.77 kgf/cm2 respectively; thus, P. bambusoides was found to have the highest compressive strength.

### 2 Wood material characteristics at different sampling heights among bamboo species

#### 2.1 Physical properties

We measured the volume and density of the dominant bamboo species at different heights, the results of which are shown in Fig. 1, 2, and 3. In all three species, the volume decreased from 1 to 21 nodes, with the greatest decline occurring in P. pubescens. In all three species, density was the highest at the 21st node. Our results were similar to those of Jin et al. (2014), who reported that fiber ratio, specific gravity, and compressive strength were all higher in the upper sections of bamboo stalks. Moreover, the density of fiber bundles increased from the lower parts of bamboo to the upper parts, and as a result, significant correlations were detected between the increase in density, specific gravity, and compressive strength.

The volume of P. bambusoides, P. pubescen and P. nigra decreased with sample height and the density was the highest at the 21st node. The decrease in the volume of P. pubescens was more than twice as high as that of other species.

#### 2.2 Mechanical properties

Maximum loads and compressive strength were measured and compared among the three bamboo species based on height; results are shown in Fig. 4, 5, and 6. Maximum load decreased with increasing number of bars (from 1 to 21 nodes) in all three species; likewise, seed compressive strength was highest at the 21st bar in all three species. Ahn et al. (2003), who measured density, static elastic modulus, and dynamic elastic modulus at the top, middle, and bottom of domestic bamboo shoots, found that levels for all of these properties of bamboo shoots were the highest toward the top of the stalk.

The load of P. bambusoides, P. pubescen and P. nigra decreased with labor, and the compressive strength was highest at section 21. The decrease in the maximum load of P. pubescens was more than twice as high as that of other species.

This study was conducted to assess the potential of the utilization of domestic bamboo resources by analyzing 3-year-old P. bambusoides Siebold & Zucc., P. pubescens Mazel ex Lehaie, and P. nigra var. Henonis bamboo, which constitute the three primary species of domestic bamboo in Korea, and to evaluate the physical properties of the three species, including variations in physical and mechanical properties at different stalk heights. The air-dried densities of these species were 0.89 g/cm2, 0.79 g/cm2, and 0.83 g/cm2, respectively; in order from highest to lowest, air-dried density was highest in P. bambusoides followed by P nigra, and lowest in P. pubescens. The compressive strengths of specimens of the three species prepared under the same conditions were 802.84 kgf/cm2, 624.69 kgf/cm2, and 743.77 kgf/cm2, respectively. Volume and maximum load decreased with increasing node height in all three species, whereas air-dried density and compressive strength increased with increasing node height.

In summary, the overall quality of the physical properties evaluated here and levels of compressive strength were highest in P. bambusoides and lowest in P. pubescens, with those of P. nigra intermediate between the two. In addition, we determined that density and strength characteristics of all three species with node height.

## Acknowledgement

This research was supported by National Institute of Forest Science 'Research Project [Project Number: Project (SC0500-2012-01-2017)]'.

## Figure

Physical properties of P. bambusoides, P. pubescen and P. nigra (Volume, Density).

Mechanical properties of P. bambusoides, P. pubescen and P. nigra (Maximum load, compressive strength).

## Table

Height of bamboo test specimens

Average density of three species of bamboo

Average compressive strength of three species of bamboo

## Reference

1. Ahn SY , Shin HJ , Byeon HS , Park SB and Kong YT. 2003. Physical and mechanical properties of Phyllostachys pubescens according to growth age or felling time. J. Kor. For. En. 22: 8-16.
2. Jeon WS , Byeon HS and Kim NH. 2018. Anatomical characteristics of Korean Phyllostachys pubescens by Age. Korean Wood Sci. Technol. 46: 231-240.
3. Jin QQ , Jiu LX , Xing YH , Wen JY and Si MC. 2014. Influence of characteristic inhomogeneity of bamboo culm on mechanical properties of bamboo plywood: effect of culm height. Journal of Wood Science. 60: 396-402.
4. Jung SY , Lee KS , Yoo BO , Park YB , Ju NG , Kim HH and Park JH. 2014. Freezing injury characteristics of evergreen broad-leaved trees in southern urban area, Korea. J. Korean For. Soc. 103: 528-536.
5. Korean Standards Association. 2014. KS F 2206. Method of compression test for wood.
6. Korean Standards Association. 2016. KS F 2198. Determination of average width of annual rings for wood, Determination of density and specific graviy of wood, and Method of shrinkage test for wood.
7. Kute SY and Wakchaure MR. 2013. Performance evaluation for enhancement of some of the engineering properties of bamboo as reinforcement in concrete. Journal of The Institution of Engineers (India): Series A. 94: 235-242.
8. Lee SN , Lee BH , Kim HJ , Kim SM and Eom YG. 2009. Properties evaluation of Bio-Composite by content and particle size of bamboo flour. Korean Wood Sci. Technol. 37: 310-319.
9. Park SB and Park JS. 2012. Combustion Characteristics of Bamboo Charcoal Boards. Korean Wood Sci. Technol. 40: 19-25.
10. Roh JK. 2007. Manufacture of wood veneer-bamboo Zephyr boaed: Ⅱ. Effet of manufacturing conditions on properties of composite board. Korean Wood Sci. Technol. 35: 108-117.
11. Yoo BO , Park JH , Park YB , Jung SY , Lee KS and Kim CS. 2017. Application of inventory construction for GIS-based bamboo resource assessment. Journal of the Korean Association of Geographic Information Studies. 20: 77-88.
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