Papers by Keyword: Water Resistance

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: Magnesium oxychloride cement (MOC) possesses rapid hardening, high mechanical strength, abrasion resistance, low alkali and low corrosive performances. However, its disadvantages of poor water resistance, easily deformation, moisture absorption and halogenations limit the application. A low cost-effective modifier H₃PO₄/Na₂O·xSiO₂·nH₂O was designed for MOC system. The results showed that the softening coefficient of the modified MOC reaches 0.988 by adding appropriate dosage of the modifier. Gelatinous substances in the modified MOC was produced after soaking in water, which effectively inhibit the hydrolysis of phase 5 (5Mg (OH)₂·MgCl₂·8H₂O) and the formation of Mg (OH)₂, thus improving the water resistance of MOC system. Keywords: Magnesium oxychloride cement; Water resistance; Phosphoric acid

Abstract: The paper presents new results in the building materials area. One of the solutions of the thin-walled elements obtaining can be achieved due to new additive using. The main purpose of the paper was improvement concrete properties for thin-walled constructive elements. The experimental and standard methods have been used and new complex additive for concrete. The research shows that a comprehensive additive consisting of aqueous solution of polycarboxilate polymer, silica sol and potassium nitrite is effective and makes it possible to produce high-efficiency concrete with unique properties: higher compression strength, higher crack resistance, frost resistance, water resistance, abrasion resistance. The study shows that the concrete is chemical resistant. Modified concrete can be recommended for manufacturing critical concrete structures of special purpose, for example high-rise constriction.

Abstract: The article considers a method of recycling citrogypsum – the сіtric acid production waste. A modified gypsum binder was obtained by means of dehydration of citrogypsum suspension and adding a modifier - polyacrylamide (PAA) - to it in conditions of autoclave treatment. The application of PAA as a modifying admixture causes the necessity to reduce the water-gypsum ratio (W/G) of the mix in order to prevent lamination at the molding product forming; at the same time, to provide the necessary flowability of the mix the introduction of plasticizing admixtures is needed, or the application of the harsher moulding mixtures or pressing technologies. For cylindrical samples, obtained by the compaction method at W/G=0.25 and the specific compacting pressure 20МPа, the optimal content of polyacrylamide as a modifying admixture amounts to 2% of the initial citrogypsum weight. This allows increasing the compression strength of the ready samples by more than 5 times. The samples, produced on the basis of modified gypsum binders, are characterized with high water resistance – the softening coefficient amounted to over 0.8.

Abstract: Properties of biodegrdable trays manufactured from cassava starch, sugarcane fibers and Origanum vulgare L. essential oils (OEO) were used as additives. The effect of these additives on water absorption index (WAI), water solubility index (WSI), the density and thermal analysis of the starch trays was determined. Based on the experimental results, the cassava starch incorporated with 8% essential oils and sugarcane fiber exhibited outstanding water resistance, comparing with those of polystyrene foam. It shows that the addition of OEO would have potential to enhance dimensional stability of the trays made from cassava starch.

Abstract: A promising mode of magnesia binder use in construction is dry building mixtures production. Depending on purpose they can be self-leveling, plastering, painting, primer, putty, etc. To produce those different binders, including magnesia one, can be used, depending on the desired aesthetic, environmental and anti-bacterial properties. It can be used in children's, medical, public institutions, and residential premises. The most preferable use for magnesia dry building mixes (MDBM) is as plaster for inner or outer buildings decoration. Plasters for external use have to be light, creating a ‘breathing’ coating that prevents thermal cold bridges formation, has high vapor permeability that can adjust to the equilibrium moisture content of magnesia design on the whole, has good adhesion to the coated surface and adequate frost resistance. Ordinary Portland cement and lime-silica binders are most often used for such products. Unlike materials based on these binders, magnesia products are characterized by rapid strength development under natural conditions. Therefore, the use of magnesia binders which allow obtaining high-strength, environmentally friendly and bioresistant materials for construction is particularly interesting.

Abstract: Indonesia has a tropical climate with high rainfall and experiences frequent flooding which are a major causes of road deterioration. It requires solutions one of which is to formulate an asphalt mix that has a high resistance to water, and one of the answers is to mix Crumb Rubber (CRM) with asphalt mix. The purpose of this experimental study was to investigate the effect of crumb rubber of motorcycle tire waste (CRM) on the water resistance of asphalt concrete wearing course (ACWC). CRM, passing #30 sieve size, was mixed with aggregate, five levels of CRM content were investigated in this study, namely, 0%, 0.5%, 1%, 1.5% and 3.0% respectively by weight of mix. A dry process was used in the blending of mixtures. Three of six specimens from each group were tested under standard Marshall. The remaining specimens were tested by immersing in a bath at 60°C for 24 hours. The results indicated that the 0.5% CRM mixture was the best.

Abstract: The main requirements for the sewage lining are waterproofing properties, mechanical strength, corrosion resistance, resistance to hydro-abrasive wear. Currently, neither in the literature nor in the practice of underground urban construction, there is no information about the quantitative parameters of the above requirements. This leads to uncertainty when creating new means of protection of concrete lining from the effects of external factors and aggressive media flowing through the collector tunnels. Currently, it is possible to control the characteristics of concrete (to increase its density and decrease porosity) through the introduction of additives (superplasticizers to reduce the water-cement ratio, microsilica) or coating of concrete surface materials, contributing to colmatation. It helps to increase the water resistance of concrete tunnel lining, its resistance to aggressive influences. However, this is not enough to prevent deterioration of concrete when exposed to aggressive environment. The article proposed the evaluation of the above requirements, which will solve the problem of increasing the durability of lining concrete sewers.

Abstract: Thermosetting fluorinated polyurethane coating was prepared by using fluorinated polyether polyol (FPO) as the soft segment, 4,4`-diphenylmethane diisocyanate (MDI) as the hard segment, TEA as crosslinking agent. The structure ofthermosetting fluorinated polyurethane coating was confirmed by the use of Fourier transform infrared spectroscopy (FTIR).The FPU film’s surface property was investigated by contact angle (CA),water resistance and anti-corrosion resistance measurements. The results indicated that the surface of fluorinated polyurethanes was significantly enriched with fluorine groups. The water resistance of thermosetting FPU coating was evidently better than thermoplastic FPU coating. It was also found that the surface enrichment of fluorine atoms made the fluorinated polyurethane coating had outstanding anti-corrosion resistance.

Abstract: Effect of different curing conditions on the mechanical properties of magnesium phosphate cement (MPC), and the water resistance of MPC was improved by adding slag, the influence of slag on component and microstructure of the hydrated product were studied in this paper. The additive amount of slag was 0% ,10% , 20%, 30% and 40% separately in the ratio of total amount of MPC. It indicates that the compressive strength and flexural strength increase by about 30%,40% when the amount of slag reaches 10% of phosphate cement, respectively , and the dissolution of some phosphate which has not reacted can be prevented when cured in water for days, it improves the pH value of the solution, so the main hydration product-MgKPO₄·6H₂O hard to be dissolved under alkaline environment resulting in the decreasing of porosity ,and the decrease of strength would be controlled.