Sustainability goals are essential driving principles for the development of innovative materials in the construction industry. Natural fibers represent an attractive alternative as reinforcing material due to good mechanical properties and sustainability prerequisites. The study has been focused on the comparative investigation of chemical and physical treatments of hemp hurds and their influence on the thermal behavior of main hemp constituents in air and nitrogen atmosphere. Thermal decomposition of hemp hurds involves several parallel reactions related to heat and mass transfer processes. A comparison of DSC and TG/ DTG results of hemp hurds samples before and after treatments demonstrates a better thermal stability for treated samples. It is caused by changes in chemical composition due to a partial removal of non-cellulosic components from hemp hurds structure, an increase in cellulose content and decrease in its degree of polymerization. The results show different thermal behavior of the hurds samples heated under nitrogen and air atmosphere. Based on DTG records, several-stage process of mass loss has been found for the samples under air, whereas only two-stage process under nitrogen.

In this paper, water sorption behavior of 28 days hardened composites based on hemp hurds and inorganic binder was studied. Two kinds of absorption tests on dried cube specimens in deionized water bath at laboratory temperature were performed. Short-term (after one hour water immersion) and long-term (up to 180 days) water absorption tests were carried out to study their durability. Short-term water sorption behavior of original hemp hurds composites depends on mean particle length of hemp and on binder nature. The comparative study of long-term water sorption behavior of composites reinforced with original and chemically modified hemp hurds in three reagents confirmed that surface treatment of filler influences sorption process. Based on evaluation of sorption curves using a model for composites based on natural fibers, diffusion of water molecules in composite reinforced with original and chemically modified hemp hurds is anomalous in terms of the Fickian behavior. The most significant decrease in hydrophility of hemp hurds was found in case of hemp hurds modified by NaOH and it relates to change in the chemical composition of hemp hurds, especially to a decrease in average degree of cellulose polymerization as well as hemicellulose content.

This experimental study was focused on the application of a surface-modified hemphurds aggregate into composites using an alternative binder of MgO-cement. This paper presents the results of the comparative study of the parameters (chemical and physico-chemical modification, and hardening time) affecting the physical (density, thermal conductivity coefficient and water-absorption behavior) and mechanical properties (compressive strength) of the bio-aggregate-based composite. A test of the parameters of the bio-composite samples showed some differences, which were determined by the chemical and surface properties of the modified filler, and which affected the mechanisms of hardening. The bulk density values of the hemp hurd composites hardened for 28 days place this material in the lightweight category of composites. The values of water absorption and the thermal conductivity coefficient of bio-composites decreased, and the strength parameter increased with an increase in the hardening time. The lower values of compressive strength, water absorption, and thermal conductivity coefficient (except for the ethylenediaminetetraacetic-acid-treated filler) were observed in composites based on fillers chemically treated with NaOH and Ca(OH) 2 ) compared to referential composites (based on original hemp hurds). This is related to changes in the chemical composition of hemp hurds after chemical modification. The composites with ultrasound-treated hemp hurds had the greatest strengths at each hardening time. This is related to pulping the bundles of fibers and forming a larger surface area for bonding in the matrix. demand for natural fibers is growing worldwide and its price is increasing, it is still significantly lower than that of synthetic fibers; these plants need further research with respect to the opportunities for their use, and to provide novel products with improved properties. Among a wide variety of lignocellulosic material sources, a great importance is given to technical hemp (Cannabis Sativa) for its application in bio-composites. Industrial hemp is becoming a major focus of the green housing segment because of its energy-efficient cultivation, and because hemp-based composites have no negative effects on human health [5]. The excellent physical and mechanical properties of hemp, including low density, high specific stiffness and strength, biodegradability, sound absorption, low processing costs and the ecological suitability of this fast-growing, carbon-negative and non-toxic plant, predispose it for use in building materials (bio-composites) based on inorganic matrices [6], mainly for their application in the housing construction [7]. Traditional building materials, such as concrete, are increasingly being replaced with advanced composite materials in accordance with the principles of sustainability in civil engineering. One of the options involves a partial replacement of cement with active cementitious substances, such as mineral or industrial solid byproducts and wastes (metakaolin, coal and municipal s...

The aim of this work is to study the suitability of the MgO-based cement as an inorganic binder instead of the traditional Portland cement into composites with an organic filler material such as hemp hurds. MgO-based cements, in contrast to Portland cement which requires high temperatures (about 1450 °C) during its production, demand less energy (the maximum temperature for the controlled calcination to obtain MgO from magnesium carbonate is 750 °C), becoming a more efficient cement from the environmental point of view. The first part of this paper summarises the results of physico-mechanical properties such as density, thermal conductivity, water absorbability and compressive strength of hardened hemp hurds composites that make this material useful and interesting mainly for its thermal insulating properties which can be improved by hemp hurds treatment processes. The second part of this work is devoted to the characterization of the MgO-cement matrix in the 28-day hardening stage. The MgO-based cement as an alternative binder appears to be suitable for the preparation of biocomposites based on hemp hurds.

The effort to achieve sustainable development using renewable materials instead of limited ones is the current trend in the construction industry. Need for the development of environmentally friendly products is related to industrial interest in using natural plant fibres as reinforcement in composites. The combination of organic filler and inorganic matrix creates high-quality products such as fibre boards and composites. Industrial hemp fibres are one of the mostly used natural fibres and due to their unique mechanical, thermal insulation, acoustic and antiseptic properties have a great potential in composite materials. However, improving the interfacial bond between fibre and matrix is an important factor in fibre-reinforced composites. Optimizing the adhesion between fibre and inorganic matrix is related to surface treatment processes. This paper deals with morphology characterization, study changes in the chemical composition and structure of hemp fibres using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) before and after physico-chemical treatment.