Densification and Mechanical Enhancement of Invasive South African Hardwoods: Prosopis glandulosa and Acacia mearnsii

TL;DR

This paper investigates how to improve the strength and performance of invasive South African hardwoods through densification techniques.

Contribution

The study introduces a novel approach to enhance mechanical properties of Prosopis glandulosa and Acacia mearnsii through densification and various treatments.

Findings

Partial delignification and hot pressing reduced sample thicknesses by 40% for Prosopis and 50% for Acacia.

Flexural strength increased by 216% for Prosopis and 334% for Acacia after treatment.

The study evaluated practical mechanical properties like nailing, sanding, and flame resistance.

Abstract

Wood used in construction varies in density, leading to differences in strength and rigidity. Wood densification has recently emerged as a promising technique to address these limitations and enhance material performance. This study explores the potential of two abundant and low-cost invasive hardwood species in South Africa—Prosopis glandulosa (Honey Mesquite) and Acacia mearnsii (Black Wattle)—as sources for producing densified wood. A range of strengthening methods, including chemical, pressure, and heat treatments, were applied and compared. After partial delignification and hot pressing, sample thicknesses were reduced by 40% for Prosopis and 50% for Acacia, yielding substantial increases in flexural strength of 216% (22.61 MPa) for Prosopis and 334% (24.65 MPa) for Acacia. In addition to anatomical imaging, analyses of lignosulphonate content, and thermogravimetric profiling, the study also evaluated several practical, carpentry-relevant mechanical properties. These included comparative tests for flexural and compressive strength, nailing and sanding performance, as well as assessments of water absorption, electrical resistivity, and flame-holding capacity.

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