Solid State Phenomena Vol. 296

Abstract: The study of the influence of selected temperature regime and potassium ions on the process of synthesis of belite (2CaO·SiO₂, C₂S) was carried out. The basic raw material was calcium carbonate (CaCO₃) and amorphous silica (SiO₂). The dosage of both components was based on the stoichiometric ratio of CaO:SiO₂ in belite. The modification of the raw meal was carried out in the form of potash, K₂O. Potash was dosed in the form of potassium carbonate, K₂CO₃, and potassium sulfate, K₂SO₄. The firing process was performed in a superkanthal furnace with two temperature modes, firing temperature: 1150 °C / 3 hours soaking and 1450 °C / 5 hours soaking. The evaluation performed by the experiment was based on mineralogical analysis by XRD analysis.

Abstract: In this study, the utilization of lava sand as an aggregate in lime mortars, cement-lime mortars and natural hydraulic lime mortars has been investigated. The aim of this study is to compare some physico-mechanical and microstructural properties of lava sand mortars with reference mortars with pure quartz sand. Compressive and flexural strengths were tested at mortar age of 28, 56 and 90 days. The results revealed improved flexural strengths of mortars with lava sand despite the fact that the mortars showed higher open porosity and water absorption than those with quartz aggregate. This fact predetermines the use of lava sand in non-hydrophobic remedial mortars with a high ability to salt accumulation from masonry. The applied lava sand is convenient to lime-based mortars as an aggregate, especially in regions where the lava resources are abundant.

Abstract: Lime based mortars rank to the oldest used building systems used by human civilization worldwide. These materials offer suitable properties for various applications; however its low resistance in moist environment is their significant weakness. Hence, they were modified by number of additives and admixtures. The flax oil was applied to historic mortars to achieve hydrophobization, additionally this additive has considerable influence on the properties of fresh mixture as well. This paper introduces an experimental study dealing with the influence of flax oil on the properties of fresh lime based mortars with various water-to-binder ratios. The results of rheology properties were accompanied by the determination of mechanical performance, basic shrinkage and bulk density of hardened mortars.

Abstract: Colouring of folk houses, its variations in time and sorts of pigments used has been very little explored in the region of interest so far. The paper shows the results of the investigation of twenty four coloured plaster and render samples from six object from two ethnographic regions of Moravia, Czech Republic. Polarizing microscopy, powder X-ray diffraction and Raman spectroscopy were the principal analytical methods were. The results show that all the blue colours were due to ultramarine application, red one was caused by industrial by-product of iron processing and the yellow one by ochre. The deep green was due to organic synthetic pigment, whereas the lighter shades due to green earth, a natural glauconite clay in these cases. Based on the examined set of samples, no qualitative difference in the composition of pigments were found between South Eastand Central Moravia. In both the regions not only lime but also plaster or Paris or a mixture of both the material was used to produce plasters and renders in the past.

Abstract: The aim of the research was to verify whether it is possible to use specific types of treated hazardous waste as a filler in special epoxy based polymer mortars. In particular, it was a neutralizing sludge (NS-HW) with a relatively high content of heavy metals and other hazardous substances. This alkaline sludge is formed as a by-product of galvanic plating of steel elements in the baths, which are subsequently thickened and neutralized with calcium hydroxide. During the experimental verification, it was determined what resulting mechanical properties can be achieved by using 40% of the treated neutralizing sludge as a filler. In order to compare the achieved properties, a reference filler in form of a silica flour was used in the same binding matrix, and the polymer mortar containing waste foam glass of approximately the same fraction. It was discovered that, at the same percent filling, the polymer mortar with neutralizing sludge (NS-HW) had a similar tensile strength similar and cohesion with the concrete substrate as the reference material with the silica flour. Furthermore, it has been shown that this filler lowering the environmental footprint does not affect the chemical resistance of the polymer mortar to aggressive liquid solutions. As part of the microstructure observing, the uniformity of the filler distribution in the hardened polymer mortar, the incorporation of sludge particles into the epoxy matrix, and the quality of the polymer mortar bonding to the concrete was monitored using a high resolution digital microscope.

Abstract: This study used an optimized mixture of red mud (RM), rice husk ash (RHA), diatomaceous earth (DE), and water glass solution (WGS) with silica modulus of 2.5 to produce geopolymer-based material. The geopolymer product was tested engineering properties which are in good agreement of ASTM requirements for building materials. For microstructure, the geopolymer samples were characterized by using Fourier-transform infrared spectroscopy (FTIR) and focused on evaluation on formation of aluminosilicate network in the ternary-blended geopolymer. The results showed that tetra-silicates or acid silicic (Si (OH)₄ or H₄SiO₄) dissolved and reacted with the iron oxide (Fe₂O₃) in RM and DE to form the oligomer precursors of sialate-O-Si-O-Al-O-, sialate-siloxo-O-Si-O-Al-O-Si-O-, sialate-disiloxo-O-Si-O-Al-O-Si-O-Si-O-, tetra-silicate [SiO₄]^4-, and tetra-aluminate [AlO₄]^4-. The formation of sodium alumino-silicate iron hydroxide polymeric network were easily detected by vibrational modes of –T–O–T– and –T–O–Na units (T refers to tetrahedral such as that of Si or Al) and of –OH and H–O–H. As well as, there were appearances of the membered ring or chain structural units of geopolymers.

Abstract: This paper illustrates a special investigation on geopolymer concrete synthesized from fly ash, sand, coarse aggregates (solid phases) in conditions of sodium silicate solution and seawater (liquid phases). The mixtures of geopolymer concrete were designed with proportion changes of among materials to evaluate effects of the proportions to engineering properties of products. The specimens were molded into cylinder with 200 mm in length and 100 mm in diameter, and then cured at room condition (28 °C, 80 % of humidity) for testing engineering properties for 7 days, 28 days, 90 days, and 180 days. The engineering properties of geopolymer concrete samples included compressive strength (MPa), water absorption (kg/m³), and volumetric weight (kg/m³). The results showed that the fly ash-based geopolymer concrete using sodium silicate solution and seawater was very good performance with value of 180 day-compressive strength at 58 MPa, water absorption and volumetric weight were at 180 kg/m³ and 2200 kg/m³, respectively.

Abstract: The purpose of the work was to study physico-mechanical properties of glued connections of wood rods, toothed lamellae after splicing and corner spike clamping of window frames which were obtained in the production conditions. The alkaline aluminosilicate binder-based adhesive (glue) of the composition 0.8Na₂O·Al₂O₃·4.5SiO₂·20H₂O modified using organo-mineral additives was used in testing. After solidification of the adhesive, the samples were cut to determine the strength of frame corner joints in bending, glued timber connections for splitting along the grains, toothed glued connections in bending and water resistance of the glued connections of timber elements. The results of these tests showed high values of strength characteristics in case of the proposed modified alkaline aluminosilicate binder-based adhesive (glue), which were by 1.5 times higher than those in case of the WoodMax (D2) taken as a reference glue, and in water resistance complied with Class D2/D3 as per PN-EN 204.

Abstract: Fiber concrete is a specific kind of concrete which is enriched by suitable type of fibers during its manufacturing process. Due to this fact, better physical and mechanical properties are achieved according to the requirements. To achieve the best quality of the concrete it is necessary to choose the most suitable type of fibers and determine their exact dosage. Alkali-activated systems have been significantly developed in recent years. These are composites that could at least partly replace the Portland cement based materials in the future. This paper deals with the determination of the influence of the type of fibers used on the basic physical-mechanical properties of prepared mixtures and their comparison with the reference mixture. In particular, two types of activators of sodium water glass and anhydrous disodium silicate were used as activator in the experiment. In the experiment, a blast furnace slag was used as a binder. Flexural and compressive strengths were tested and the bulk density, deflection and dynamic modulus of elasticity were determined.

Abstract: This paper reports on the possibility of using natural renewable materials as hemp fibers in the preparation of composites. The design and preparation of durable composites also requires the selection of suitable alternative binders, in order to reduce the production of carbon dioxide in the production of cement. The paper will present the results of composites with partial replacement of cement with natural clay, which was used in the traditional building in the past as classical binder. Experimental verification of mechanical, thermal and humidity parameters of composites was performed. The results confirmed some prospects for the use of experimental composites in terms of the compressive strengths values obtained after 28 days of maturing. Highest compressive strengths were measured for a reference set with 100% cement content and of course composites with increasing percentage cement replacement exhibited lower strengths. The results showed that replacing cement with natural clay does not create a new stronger material, but there is some potential for its use in the form of non-load-bearing elements. Experimental composites exhibited a relatively lower density compared to normal concrete, but the thermal conductivity values indicate the potential for their use as insulating materials.