Indoor air quality in buildings: Assessment of exposure to enhanced natural radioactivity

Our study aimed to assess air quality within buildings constructed with coal ash concrete, with a specific focus on radon measurement. Coal ash, a by-product of the TAQA Morocco thermal power plant. In this investigation, two concrete mixtures were prepared. It is possible that concrete produced from coal ash may contain elevated levels of radon, a naturally occurring radioactive gas that could prove detrimental to human health, given that coal ash contains considerable quantities of radioactive elements. To this regard, two nuclear techniques were employed for analysis: high-resolution gamma spectrometry and alpha dosimetry based on the use of LR115 on the two concrete mixes. The equivalent radium activity (Raeq), internal (Hin) and external (Hex) risk indices, absorbed dose rate (Ḋ), annual effective dose (Ė) and excess lifetime cancer risk (ELCR) were also calculated. The surface (ES) and mass (EM) radon exhalation rates were calculated for the analysed samples in order to assess the radiological risks resulting from the use of coal ash concrete.The results has revealed no evidence of any health risks to the general public, and therefore coal ash concrete can be used in construction projects

Vegetal fibers in polymeric composites: a review

The need to develop and commercialize materials containing vegetal fibers has grown in order to reduce environmental impact and reach sustainability. Large amounts of lignocellulosic materials are generated around the world from several human activities. The lignocellulosic materials are composed of cellulose, hemicellulose, lignin, extractives and ashes. Recently these constituents have been used in different applications; in particular, cellulose has been the subject of numerous works on the development of composite materials reinforced with natural fibers. Many studies have led to composite materials reinforced with fibers to improve the mechanical, physical, and thermal properties. Furthermore, lignocellulosic materials have been treated to apply in innovative solutions for efficient and sustainable systems. This paper aims to review the lignocellulosic fibers characteristics, as well as to present their applications as reinforcement in composites of different polymeric matrices.Fundação Cearense de Apoio ao Desenvolvimento Cientifico e TecnologicoFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Embrapa Agroind Trop, Fortaleza, Ceara, BrazilUniv Estadual Paulista UNESP, Fac Engn Guaratingueta, Dept Mat &Tecnol, Guaratingueta, SP, BrazilCtr Univ Volta Redonda UniFOA, Volta Redonda, RJ, BrazilDepartamento de Materiais e Tecnologia, Faculdade de Engenharia de Guaratinguetá, Universidade Estadual Paulista – UNESP, Guaratinguetá, SP, BrazilFundacao Cearense deApoio ao Desenvolvimento Cientifico e Tecnologico: DCR-0024-00522.01.00/12FAPESP: 2011/14.153-

Biocomposites based on PLA and natural microfibers, Effects of structures and amounts on morphological, thermal, and rheological properties

International audienceThis research focuses on the development of bio composites based on polylactic acid (PLA) and natural fibers, particularly sugarcane bagasse (SCB). These bio-based and biodegradable materials are selected for their environmental benefits, positioning them as innovative eco-friendly bio composites. First, the fiber surface was treated with an alkaline solution to remove non-cellulosic components, ensuring better compatibility and improving interfacial adhesion with the polymer matrix. Various amounts of fibers were dispersed within the PLA matrix. The composite materials were produced using two methods: melt processing and solvent casting. The primary objective is to achieve high fiber dispersion and homogeneous bio composites. The dispersion state was analyzed using scanning electron microscopy (SEM). Additionally, the thermal, mechanical, and rheological properties of these PLA-based bio composites were investigated. The present study highlights that the solvent method allows for the production of composites with homogeneous fiber dispersion while preserving their initial morphology. However, this method presents ecological drawbacks and challenges for industrial-scale development. In contrast, the melt processing method ensures good fiber dispersion and, despite some degree of fiber damage, does not significantly compromise the desired properties