Durability of Superheated Steam-Treated Light Red Meranti (Shorea spp.) and Kedondong (Canarium spp.) Wood against White Rot Fungus and Subterranean Termite

Rasdianah Dahali,Seng Hua Lee,Edi Suhaimi Bakar,Pui San Khoo,Qamariah Norhidayah Salleh,Zaidon Ashaari,Hidayah Ariffin,Paiman Bawon

doi:10.3390/su12114431

Abstract

In this study, the effect of superheated steam (SHS) treatment on the changes of the chemical composition and biological properties of two tropical hardwoods was investigated. SHS was carried out on light red meranti (Shorea spp.) and kedondong (Canarium spp.) wood with dimensions of 410 × 25 × 25 mm, using superheated steam as the heating medium. Wood samples were heat-treated at nine treatment levels, ranging from 172 to 228 °C and 95 to 265 min, respectively. The chemical constituents and resistance against white rot fungus (Pycnoporus sanguineus) and subterranean termite (Coptotermus curvignathus) of the treated wood were evaluated. A significant reduction in holocellulose content and increment in lignin was observed after SHS treatment. Consequently, the resistance against white rot fungus and termites improved. The biological durability improved with an increasing treatment temperature and time. A regression analysis revealed that the reduced equilibrium moisture content imparted superior biological resistance to the treated wood. Weight loss caused by the thermal degradation also served as a good indicator for fungal decay, as the loss of weight was directly proportional to the improvement in fungal resistance. However, this did not apply to termite resistance, as a very weak relationship was found between the two variables.

Highlights

Sufficient water within cell walls or wet wood and the contact of the wood with soil provides a favorable condition for fungi and termites in degrading wood in use [1]
Norway spruce, silver fir, European ash, and European beech were heat-treated by Gao et al [17] and the results revealed significant improvement in the resistance against both white rot and brown rot fungi observed at treatment temperatures between 200–220 ◦C
The aims of this study were to determine the effectiveness of superheated steam treatment on the improvement of resistance against white rot fungus (Pycnoporus sanguineus) and termites (Coptotermus curvignathus) for both of the wood species examined in the present study

Summary

Introduction

Sufficient water within cell walls or wet wood and the contact of the wood with soil provides a favorable condition for fungi and termites in degrading wood in use [1]. As a result of the degradation caused by these wood destroying organisms, millions of USD are spent each year to replace the decayed wood products. This results in economic losses, with far-reaching impact on the increasing demand for timber. An estimation of 40 billion USD economic loss is reported worldwide annually as a result of termite attacks on building structures [2]. In the year of 2010, the economic losses caused by subterranean termites was approximately 32 billion USD for preventive measures and damage repairs [3]. It has been reported that the financial losses in the USA alone due to wood decay are amounted to around 300 million USD annually, not including the cost of protective measures

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