Properties of fly ash-based spray-applied fire resistive materials

Spray-applied fire-resistive materials (SFRMs) are one of the most commonly used passive fire protection materials due to their low thermal conductivity, lightweight, cost-effectiveness, and ease of application. Gypsum and Portland cement are commonly used in SFRMs to bind lightweight fillers and fibres. Due to the wide application of SFRMs, their production consumes large amounts of natural and non-renewable resources and contributes significantly to greenhouse gas emissions. This paper investigates the feasibility of using industrial by-products (e.g., fly ash) and waste materials (e.g., waste glass) to manufacture SFRMs with the aim of reducing the environmental impact. Accordingly, three SFRMs with different densities were developed utilising fly ash blended cement (FAC) and expanded glass. The use of FAC significantly reduced the use of Portland cement by 81% and achieved a 28-day compressive strength of 33.8–46.3 MPa for the binder. The developed SFRMs had average densities of 345 kg/m3, 560 kg/m3, and 698 kg/m3 for low-, medium-, and high-density groups, respectively. The compressive strengths of the SFRMs ranged from 747 kPa to 888 kPa, 6188 kPa to 7314 kPa, and 2343 kPa to 3535 kPa for the corresponding three groups, respectively. Additionally, the bond strengths of the corresponding SFRMs are 14.4 kPa–19.3 kPa (low-density), 34 kPa–40.9 kPa (medium-density), and 51.5 kPa–85.1 kPa (high-density), respectively. All the tested SFRMs met the requirements for density, compressive strength, bond strength, and non-combustibility. The thermal properties of the developed SFRMs were comparable to those of commercially available cementitious-based SFRMs in the same density group. In addition, using FAC instead of Portland cement could reduce carbon emissions by 68.4% and save costs by 38.4% in the Australian context

Thermal and pyrolysis kinetics analysis of glass wool and XPS insulation materials used in high-rise buildings

This study investigates the kinetics data of glass wool (GW) and extruded polystyrene (XPS) insulation materials used in cladding systems using a systematic framework. The determination of appropriate kinetic properties, such as pre-exponential factors, activation energy and reaction orders, is crucial for accurately modelling the full-scale fire performance of insulation materials. The primary objective of this research is to extract thermal and kinetics data of XPS and GW insulation materials employed in high-rise buildings. To obtain these properties, thermogravimetric analysis (TGA) is conducted at four different heating rates: 5, 10, 15 and 20 K/min. The TGA results serve as the basis for determining the kinetic properties using a combination of model-free and model-based methods. The outcomes of this study are expected to be highly beneficial in defining the pyrolysis reaction steps and extracting kinetics data for fire modelling of such insulation materials. This information will enhance the understanding of the fire behaviour and performance of these materials during fire incidents, aiding in developing more accurate fire models and improving fire safety strategies for cladding systems in high-rise buildings

Testing of aluminium composite panels in a cone calorimeter : a new specimen preparation method

Fire testing data consistency and repeatability are essential for regulatory scrutiny, product development, and fire modelling of the lightweight cladding system. Lightweight composite claddings such as aluminium composite panels (ACPs) have been challenging to assess in terms of combustibility and flammability due to their sandwiched composite structures, which led to inconsistent data during bench-scale fire testing and fire risk assessment. This study aims to improve the test data consistency of reaction-to-fire properties such as time to ignition (tign), peak heat release rate (pHRR), time to peak heat release rate (tpHRR), total heat release (THR), which are the critical parameters for fire assessment and regulatory screening of the ACP claddings used in buildings. Therefore, a modified test approach is proposed in this study to facilitate the proper combustion process with the formation of a steady fuel gas/air mixture during the testing of cladding panel. The test data repeatability, standard deviation (SD) and relative standard deviation percentage (RSD%) of reaction-to-fire properties have been improved significantly with the modified test approach compared with the existing test approach

Cellulose consolidation under high-pressure and high-temperature uniaxial compression

Materials based on cellulose cannot be obtained from thermoplastic processes. Our aim is to prepare all-cellulose materials by uniaxial high pressure thermocompression of cellulose. The effect of moisture content (0–8 w/w%) and temperature (175–250 °C) was characterized through the mechanical properties (bending and tensile), morphology (scanning electron microscopy, X-ray tomography) and microstructure (viscometric degree of polymerization, Raman spectroscopy, X-ray diffraction, solid-state NMR) of the specimens. The specimens were mechanically stronger in bending than in tension. They exhibited a more porous heart, a dense but very thin skin on the faces (orthogonal to the compression axis) and thick and extremely dense sides. During thermocompression severe friction between fibers caused a decrease in molecular weight while heating above the glass transition temperature was responsible for water migration towards the specimen heart. Most of the cohesion came from the small sides of the test samples (parallel to the compression axis) and seemed mainly related to the entanglement of amorphized cellulose at the interface between particles. Around 200 °C water accumulated and provoked delamination upon pressure release, but at higher temperatures water, in a subcritical state, may have been consumed during the hydrolysis of amorphous cellulose regions. The all-cellulose material with the best mechanical properties was obtained at 2% moisture and 250 °C. This work shows that thermocompression at high temperature with limited moisture may be viable to produce renewable, sustainable all-cellulose materials for application in biobased plastic substitutes including binderless boards

Photodynamic treatment of human breast and prostate cancer cells using rose bengal-encapsulated nanoparticles

Cancer, a prominent cause of death, presents treatment challenges, including high dosage requirements, drug resistance, poor tumour penetration and systemic toxicity in traditional chemotherapy. Photodynamic therapy, using photosensitizers like rose bengal (RB) with a green laser, shows promise against breast cancer cells in vitro. However, the hydrophilic RB struggles to efficiently penetrate the tumour site due to the unique clinical microenvironment, aggregating around rather than entering cancer cells. In this study, we have synthesized and characterized RB-encapsulated chitosan nanoparticles with a peak particle size of ~200 nm. These nanoparticles are readily nternalized by cells and, in combination with a green laser (λ = 532 nm) killed 94–98% of cultured human breast cancer cells (MCF-7) and prostate cancer cells (PC3) at a low dosage (25 μg/mL RB-nanoparticles, fluence ~126 J/cm2, and irradiance ~0.21 W/cm2). Furthermore, these nanoparticles are not toxic to cultured human normal breast cells (MCF10A), which opens an avenue for translational applications

Self-assembly of a rare high spin FeII/PdII tetradecanuclear cubic cage constructed via the metalloligand approach

Polynuclear heterobimetallic coordination cages in which different metal cations are con-nected within a ligand scaffold are known to adopt a variety of polyhedral architectures, many of which display interesting functions. Within the extensive array of coordination cages incorporating Fe(II) centres reported so far, the majority contain low-spin (LS) Fe(II), with high-spin (HS) Fe(II) being less common. Herein, we present the synthesis and characterisation of a new tetradecanu-clear heterobimetallic [Fe8 Pd6 L8 ](BF4 ]28 (1) cubic cage utilising the metalloligand approach. Use of the tripodal tris-imidazolimine derivative (2) permitted the formation of the tripodal HS Fe(II) metalloligand [FeL](BF4)2·CH3 OH (3) that was subsequently used to form the coordination cage 1. Magnetic and structural analyses gave insight into the manner in which the HS environment of the metalloligand was transferred into the cage architecture along with the structural changes that accompanied its occupancy of the eight corners of the discrete cubic structure

Prominent members of the human gut microbiota express endo-acting O-glycanases to initiate mucin breakdown

Epithelial cells that line the gut secrete complex glycoproteins that form a mucus layer to protect the gut wall from enteric pathogens. Here, the authors provide a comprehensive characterisation of endo-acting glycoside hydrolases expressed by mucin-degrading members of the microbiome that are able to cleave the O-glycan chains of a range of different animal and human mucins