The influence of heat on mechanical properties of Dendrocalamus giganteus bamboo

Bamboo is a sustainable material with a high potential to replace high-contaminating materials such as steel and concrete in many uses. However, some properties, such as the resistance to pests and dimension stability, must be improved for bamboo to be accepted by the engineering community. A low-cost way to improve dimension stability and resistance against pests is to expose the material to heat. This paper presents the results of an investigation on the effect of heat exposure on the mechanical properties of Dendrocalamus giganteus (DG) bamboo. The mechanical tests were performed to specimens previously heated during either 3 or 24 h at each of six temperatures in the range 100-225 degrees C. The mechanical characterization included axial and transverse tensile experiments, axial compression, and non-destructive dynamic tests to determine the dynamic flexural modulus (DFM). The effect of moisture content on mechanical properties was also measured by using untreated specimens at dry and at equilibrium moisture content (EMC) conditions. The different moisture content of the specimens from dry to EMC did not change the ultimate tensile strength (UTS), while the difference between ultimate compression strength (UCS) at EMC and dry conditions was significant and this result shows the remarkable influence of the matrix mechanical properties on the UCS. A tangible reduction in UTS and ultimate transversal tensile strength (TUTS) occurred at temperatures higher than 150 degrees C while the DFM was not reduced significantly and nearly remained the same for specimens heated during 3 hat temperatures lower than 200 C. Results of this study can be taken as guidelines to plan heat exposure cycles intended to improve the dimension stability and pest resistance of the raw material as well as to assess changes in the mechanical properties during the manufacture of products such as densified bamboo.

Automated summary

Bamboo is a sustainable material with potential to replace high-contaminating materials, but improvements in properties are needed for acceptance in the engineering community. Heat exposure can enhance the dimension stability and resistance against pests of bamboo.