**8.1. Plant material quality control**

Given the low natural durability value of bamboo species, an adapted design scheme making allowance for the wooden element deterioration process can be adopted [26]. In order to give answer to cross-sectional losses because of decay processes at the internal stability design

**Figure 4.** (A) Sliding check and (B) overturning check. The bamboo root effect (if applicable) is highlighted within the

In the last two cases, lower forces will be exerted on the bamboo culms, and, therefore, lower diameters will be able to withstand them and ensure the internal stability of the bamboo structure. A complete example of the preceding design approach can be found in [26, 29].

**Figure 5.** Example of stress diagrams for the vertical and horizontal elements in a bamboo palisade [29], where q is

), L is the length of the element (m), H is the height of the vertical element and Ka is the

• Increase of the initial diameter of the bamboo culms used in the work

level, different strategies can be followed:

circle (adapted from [26]).

122 Bamboo - Current and Future Prospects

the distributed load (kN/m<sup>2</sup>

coefficient of active earth pressure (dimensionless).

• Reduction of the elements bending span length

• Reduction of the height of the retaining structures

There are a large number of species of bamboo native to different world regions, mainly in the warm and moist tropical and warm temperate climates. Current standards recognize that methods of identification of bamboo through anatomical characteristics have not been perfected. To mitigate against the risk of selecting inadequate/untested species, experienced sorters should be employed in identification through morphological characteristics on full standing culm and the results recorded in the QAM.

Quality control must ensure that only matured bamboo of at least 4 years of age shall be used in construction, preferably after at least 6 weeks after felling. Experienced quality assessors should ensure that solid bamboo culms or culms with thicker walls and closely spaced nodes are selected for structural use. Conversely, the quality assurance control must ensure that any broken, damaged or collapsed bamboo shall be rejected while dead/immature/infected bamboos shall be avoided.

If living bamboo is to be used in the structure, the origin/provenance of the bamboo seeds/ seedlings/plantings should be recorded in the QAM together with the species name(s), application/planting rate/density, fertilizer, mulching, soil preparation and maintenance requirements. This must be supported by certificates relating to type, origin, quality and validity of seeds/plants and quality of fertilizers.

Knowing that the natural durability of bamboo is relatively low (12–24 months when used in the open and in contact with the soil but depending on the species and environmental conditions), and its strength decreases rapidly with the onset of fungal decay, suitable treatment (traditional treatments if possible) for preserving bamboo must be applied considering the environmental impact and health aspects of labour and all users of the structure. The samples for testing the effect of preservatives must be cut from treated bamboo for chemical analysis (e.g. a weight of approx. 100 g per 100 kg bamboo treated).

Air-dried bamboo should be used whenever possible in order to ensure it deteriorates more slowly. QC should ensure that, if the bamboo delivered to site is wet, there is an opportunity to dry again before it is applied in the soil bioengineering structure.
