Papers by Keyword: Chemical Resistance

Abstract: This paper deals with research and development of a new chemically resistant sprayed mixture based on portland cement and special admixtures. The new material will be part of a comprehensive remediation system for the remediation of chemically attacked and stressed sewer structures. The aim of this work is to verify the effect of the amount of crystalline waterproofing admixture on selected physical-mechanical characteristics and chemical resistance, specifically resistance to the attack of sulphate solution and the attack of aggressive biogenic sulfuric acid solution. Furthermore, the resulting characteristics of test specimens manufactured in the laboratory and test specimens made by spraying into boxes and subsequent cutting to the required dimensions were compared. Due to the fact that there is currently no official methodology in the Czech Republic for testing the chemical resistance of cementitious materials intended for sewage environments, the methodology was used in accordance with DIN 19573 "Draft on mortars for construction and rehabilitation sewer systems". The sulphate resistance was determined for test specimens measuring 160×40×10mm, which were exposed to a solution of sulphate salts with a concentration of 29.8g / l (44g/l Na₂SO₄) for 91days. To determinate the resistance to biogenic sulfuric acid, special tanks were assembled in which the test specimens, measuring 80×40×40mm, were exposed for 14 days to a solution of sulfuric acid (H₂SO₄) with a molar concentration of 1,0mol/l (pH=0). The results of this work show the optimal amount of crystalline waterproofing admixture. The results of this work will be used in the next phase of research, when cement and some fillers will be substituted by selected secondary raw materials, namely to improve or at least maintain the key characteristics of the final sprayed mixture. Keywords: Sprayed mixture, Sulphates, Biogenic sulfuric acid, Chemical resistance, Crystalline waterproofing admixture

Abstract: The article shows that synthetic wollastonite, obtained on the basis of a mixture of calcium oxide and silicon oxide, as well as calcium carbonate and silicon dioxide, increases the thermal stability of epoxy materials filled with it. The chemical and atmospheric resistance of epoxy films filled with wollastonite is on average 0.2 – 0.3% lower than that of the base composition, which is probably due to the porosity of both synthetic and natural wollastonite. The phase composition of synthetic wollastonite does not significantly affect chemical resistance of epoxy materials filled with it. The chemical resistance of epoxy compositions, regardless of their composition, is lower in weakly acidic solutions and water, in comparison with weakly alkaline and saline solutions.

Abstract: The paper presents the results of a study of the chemical resistance and mechanical properties of polyphenylene sulfone manufactured by Solvay, Radel brand, obtained by injection molding. Chemical resistance was investigated in short-term tests (24 hours duration), standard (7 days) and long-term (16 weeks). The mechanics of PPSU samples after exposure to chemical reagents is presented. It was revealed in what chemical environments and how much the mechanical properties of polyphenylene sulfone are preserved.

Abstract: New protective coating compositions based on epoxy resins with high rates of chemical resistance to etching solutions are developed. The chemical resistance coefficient ranges from 0.7 to 0.96. The curing process was evaluated via IR spectroscopy. For each composition, the following parameters were determined: impact strength A, compressive strength σ_compr and bending strength σ_bend, adhesion shear strength σ_shear, glass transition temperature T_gt, high elasticity modulus E_h and mesh density n_m.

Abstract: This work deals with the basic research and development of new technologies of cement-based invert grouting, in the recipe of which the appropriately selected secondary raw materials will be used as much as possible. This new grout will be part of a new comprehensive system for the remediation of chemically exposed building structures, such as sewers, silage pits and wastewater treatment plants. The aim of this work is to monitor the influence of the method and the degree of homogenization of the developed recipes on selected physical-mechanical properties of the injection material. For the needs of this work, several basic recipes were proposed, as well as the methodology of production of test specimens, their storage and testing. At the same time, three homogenization methods were chosen, differing in the manner and degree of implementation. The basic characteristics of grouting materials, which were monitored in this work, include the viscosity and processability of fresh material. Due to the requirement for increased resistance of the new material, the compressive strength and absorbency of the hardened test specimens 40 × 40 × 160 mm were monitored depending on the maturation time. The research results so far show that thorough homogenization has a fundamental effect on achieving the required physical-mechanical properties. The final methodology of homogenization of dry components will be used in the pre-preparation of all materials of the new chemically resistant remediation system, including the sprayed mixture.

Abstract: The jute polyethylene composites were developed using the hot-press technique with different fiber weight ratios. Due to the hydrophilic nature of fiber, it exhibited poor interfacial interaction to hydrophobic polymer matrix. In order to enhance the interfacial interaction between fiber and polymer, the benzene diazonium salt (BDS), propionic anhydride (PA), and 3-isocyanatopropyl triethoxysilane (silane) treated jute were used for the manufacturing of composites in this study. The chemical resistance tests of prepared composites were performed in order to probe whether these are resistant to various chemicals such as: acids, alkalis, and solvents. The effect of chemical treatments of the composites have been investigated. It was observed that the fabricated composites were resistant to all chemicals except carbon tetrachloride. The treated jute composites showed higher chemical resistance than raw jute composite and silane treated jute composite yield the highest resistance which can be suggested for making the water and chemical storage tanks.

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: Recycled poly(ethylene terephthalate) (rPET) from post-consumer drinking bottles was added into poly(butylene succinate) (PBS), which aimed to improve chemical resistance and also reduce cost. PBS and rPET with the weight ratios of 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 wt% were melt blended using glycidyl methacrylate (GMA) of 0, 3, and 5 phr as a compatibilizer and dicumyl peroxide (DCP) of 0.5 phr as an initiator. It was found that increasing rPET content enhanced Young’s modulus of the blends. However, tensile strength, and elongation at break of the blends were reduced due to phase separation. Incorporating GMA improved chemical compatibility resulting the PBS/rPET blends to have higher tensile strength and elongation at break. Compared to pure PBS, blending rPET improved chemical resistance to household chemicals such as bathroom cleaning liquid (hydrochloric acid based) and bleaching liquid, which the blends adding GMA showed even better chemical resistance.

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 work deals with the use of waste glass to the polymer anchor material based on epoxy resin, primarily for anchoring to a high strength concrete (HSC). The main aim was to use the largest possible amount of the waste packaging glass by reducing the amount of epoxy resin, which is an expensive material and its production has a negative impact on the environment. Within the experimental verification, the influence of waste packaging glass fraction 0–0.63 mm on the final properties of the polymer anchoring material was observed. To determine the optimal formulation compressive strength, flexural strength, chemical resistance, shrinkage and pull-out test were performed. Based on the evaluation of the results the optimal percentage of filling was determined, when the polymer anchor material showed high strengths, minimal shrinkage, good chemical resistance, optimal consistency for anchoring into the HSC and high anchor bolt pull-out strength.