Using waste biomass to produce 3D-printed artificial biodegradable structures for coastal ecosystem restoration.

The loss of ecosystem functions and services caused by rapidly declining coastal marine ecosystems, including corals and bivalve reefs and wetlands, around the world has sparked significant interest in interdisciplinary methods to restore these ecologically and socially important ecosystems. In recent years, 3D-printed artificial biodegradable structures that mimic natural life stages or habitat have emerged as a promising method for coastal marine restoration. The effectiveness of this method relies on the availability of low-cost biodegradable printing polymers and the development of 3D-printed biomimetic structures that efficiently support the growth of plant and sessile animal species without harming the surrounding ecosystem. In this context, we present the potential and pathway for utilizing low-cost biodegradable biopolymers from waste biomass as printing materials to fabricate 3D-printed biodegradable artificial structures for restoring coastal marine ecosystems. Various waste biomass sources can be used to produce inexpensive biopolymers, particularly those with the higher mechanical rigidity required for 3D-printed artificial structures intended to restore marine ecosystems. Advancements in 3D printing methods, as well as biopolymer modifications and blending to address challenges like biopolymer solubility, rheology, chemical composition, crystallinity, plasticity, and heat stability, have enabled the fabrication of robust structures. The ability of 3D-printed structures to support species colonization and protection was found to be greatly influenced by their biopolymer type, surface topography, structure design, and complexity. Considering limited studies on biodegradability and the effect of biodegradation products on marine ecosystems, we highlight the need for investigating the biodegradability of biopolymers in marine conditions as well as the ecotoxicity of the degraded products. Finally, we present the challenges, considerations, and future perspectives for designing tunable biomimetic 3D-printed artificial biodegradable structures from waste biomass biopolymers for large-scale coastal marine restoration.

An Experimental Evaluation of Hemp as an Internal Curing Agent in Concrete Materials.

The construction industry is facing increased demand for adopting sustainable 'green' building materials to minimise the carbon footprint of the infrastructure sector to meet the United Nations 2030 Sustainability Goals. Natural bio-composite materials such as timber and bamboo have been widely used in construction for centuries. Hemp has also been used in different forms in the construction sector for decades for its thermal and acoustic insulation capability owing to its moisture buffering capacity and thermal conductivity. The current research aims to explore the possible application of hydrophilic hemp shives for assisting the internal curing of concrete materials as a biodegradable alternative to currently used chemical products. The properties of hemp have been assessed based on their water absorption and desorption properties associated with their characteristic sizes. It was observed that, in addition to its excellent moisture absorption capacity, hemp released most of its absorbed moisture into the surroundings under a high relative humidity (>93%); the best outcome was observed for smaller hemp particles (<2.36 mm). Furthermore, when compared to typical internal curing agents such as lightweight aggregates, hemp showed a similar behaviour in releasing its absorbed moisture to the surroundings indicating its potential application as a natural internal curing agent for concrete materials. An estimate of the volume of hemp shives required to provide a similar curing response to traditional internal curing techniques has been proposed.

Life cycle assessment of end-of-life engineered wood.

Medium-density fibreboards (MDFs) and particleboards are engineered woods well-known for durability and structural strength. Wood shavings or discarded wooden products can be used for MDF and particleboard production. However, engineered woods are hard to manage at the end of their useful life due to the utilisation of binders or resins, which are known forms of carcinogens. Like other wood products, MDFs and particleboards can either be recovered for material recycling or energy recovery or sent to the landfill. This paper aims to identify the sustainable circular economy pathways for waste MDF and particleboard management, comparing three different scenarios: landfill, recycling, and energy recovery (incineration) via life cycle assessment methodologies (LCA). Life cycle assessment has been conducted using ReCiPe methodology of conducting life cycle assessment. The data analysis was conducted in MS Excel using @Risk v8.2 add-on function. The analysis was based on relative contribution of the impacts across the individual life cycle stages and the specific toxicity impacts were represented on a tornado chart to reflect the percentage spread of impacts across the life cycle phase. Finally, uncertainty analysis was conducted using Monte Carlo Simulation. The results showed that material recovery is preferred over energy recovery for most of the impact categories. However, energy recovery is preferred in the case of climate change and fossil fuel depletion. For both types of engineered wood products considered in this paper, end-of-life management of engineered woods has less impact than the production process. Toxicity impacts are the greatest for energy recovery compared with landfill and material recovery.

A Review on Flexural Properties of Wood-Plastic Composites.

Wood-plastic composite (WPC) is a kind of composite material that is made of plastic and wood fiber or wood powder. Because it is mothproof, is resistant to corrosion, and has plasticity, among other advantages, it has been researched and used increasingly in building materials. The flexural property of WPC is an important subject in evaluating its mechanical properties. In this paper, wood-plastic raw materials and processing technology are introduced; the internal and external factors of WPC which affect the flexural properties are analyzed; the different ways of enhancing the bending capacity, including the surface pretreatment, addition of different modifiers (compatibility agent and coupling agent) etc. are summarized; and the methods of operation and strengthening effect are analyzed. This work provides a reference for further research in related fields.