The effect of chemical treatment of hemp hurds slices in three solutions (EDTA (Ethylenediaminetetraacetic acid), NaOH and Ca(OH)₂) on the properties of natural material was discussed in this paper. Changes in the morphology, chemical composition and structure as well as thermal stability of hemp hurds before and after their modification were investigated by using FTIR (Fourier transform infrared spectroscopy), XRD (X-ray powder diffraction analysis) and TG (thermogravimetry)/DSC (differential scanning calorimetry). Size exclusion chromatography (SEC) measurements were used for determination of degree of cellulose polymerization of hemp hurd samples. Chemical modification is related to the partial removal of non-cellulosic components of lignin, hemicellulose and pectin as well as waxes from the surface of hemp hurd slices. Another effect of the chemical treatment applied is connected with increasing the crystallinity index of cellulose determined by FTIR and XRD methods. Decrease in degree of cellulose polymerization and polydispersity index in chemically modified hemp hurds compared to the original sample was observed. Increase in thermal stability of treated hemp hurd was found. The most significant changes were observed in alkaline treated hemp hurds by NaOH.

Development of lightweight composite materials based on organic binder is oriented on conventional inorganic binders replacement by alternative materials such as MgO cement. The objective of this paper is lightweight composites preparing with hemp shives and conventional binders (hydrated lime, cement) replacement by MgO cement. The achieved experimental results of compressive strength and thermal conductivity of hardened composites indicate that the use MgO cement based on the milled caustic magnesite is suitable conventional binders replacement in hemp concrete

This article describes utilization of a cement kiln bypass dust utilization as an added component in a hydraulic road binder. Three experimental binder mixes (BM1–BM3) with variation in the composition of the main constituents (cement clinker, ground limestone and ground granulated blast furnace slag) and constant content of bypass dust (10%) were prepared under laboratory conditions. The properties of binder constituents, fresh experimental binder mixes and hardened specimens were tested according to STN EN 13282-2 for a normal hardening hydraulic road binder. The physical and chemical properties of all binder mixes (fineness: +90 µm ≤ 15 wt.%; SO₃ content: <4 wt.%) met the standard requirements. The bypass dust addition led to an increase in the water content for standard consistency of cement mixes (w/c = 0.23) and to a shortening of the initial setting time for two experimental blended cement pastes (BM1 and BM3) compared with the value required by the standard. Only BM2 with the lowest SO₃ content (0.363 wt.%) and the highest percentage of granulated blast furnace slag (9.5 wt.%) and alkalis (Na₂O and K₂O content of 5.9 wt.%) in the binder mix met the standard value for the initial setting time (≥150 min). The results of compressive strength testing of experimental specimens after 56 days of hardening (59.2–63.9 MPa) indicate higher values than the upper limit of the standard requirement for the N4 class (≥32.5; ≤52.5 MPa).

All composites based on natural fibers absorb moisture in humid atmosphere and when immersed in water or capillary action. Therefore, one of the major drawbacks of polymer fibers is their high availability to moisture sorption and their heterogeneity, which leads to a weak interface between the fibers and matrix and a poor transfer of the applied stress between the materials, resulting to reduction of physico-mechanical properties. An experimental investigation was conducted to testing the water absorption of hemp composites with MgO-cement binder and its influence on the physico-mechanical and thermal characteristics of composites. The achieved results of composites indicate that water absorption test has deteriorative influence on observed properties due to the degradation of the fibre-matrix interface.

All composites based on natural fibers absorb moisture in humid atmosphere and when immersed in water or capillary action. Therefore, one of the major drawbacks of polymer fibers is their high availability to moisture sorption and their heterogeneity, which leads to a weak interface between the fibers and matrix and a poor transfer of the applied stress between the materials, resulting to reduction of physico-mechanical properties. An experimental investigation was conducted to testing the water absorption of hemp composites with MgO-cement binder and its influence on the physico-mechanical and thermal characteristics of composites. The achieved results of composites indicate that water absorption test has deteriorative influence on observed properties due to the degradation of the fibre-matrix interface.

The durability of building elements is influenced by a number of different factors. Among the most complicated, biocorrosion can be included without exaggeration. From practical experience, we know that biodegradation manifests itself in all kinds of materials and structural elements. Although both primary and secondary protection of a particular building structure is realized, if appropriate living conditions are created for the existence of a particular species of biodeteriogen, this kind of degradation will be initiated. The paper deals with the issue of biocorrosion, which was studied at selected parts of the technical extension in Campus of the Technical University in Košice. Undesirable bio-corrosive symptoms due to the presence of algae and fungi are often visually observed on the surfaces, but their effects also have a negative impact on the internal structure. In practical terms, a solution to identification of these symptom are required which needs to develop methods of monitoring the state of the surface over time and removing them. Diagnostic methods will be presented to check the technical state condition of construction parts as support in identification bio-corrosion symptoms.