Eco-friendly High-Strength Refractory Concrete Containing Calcium Alumina Cement by Reusing Granite Waste as Aggregate

Besides preventing valuable natural resources from going to waste, using stone waste from stone processing plants in concrete helps reduce environmental pollution and, therefore, offers a convenient route to sustainable development. The present study aims to use granite waste (GW) in high-strength refractory concrete. Sixteen high-strength refractory concrete mixes, including two water-to-binder ratios (W/B = 0.17 and 0.2), two silica-fume-to-binder ratios (SF/B = 0.15 and 0.2), two binder contents (B = 1200 and 1400 kg/m3), and two replacement ratios of silica sand by granite waste (GW/Agg = 0 and 50%) were designed and prepared with high-alumina cement (HAC). The concrete specimens were exposed to 1200 °C. Compressive and flexural strength and scanning electron microscopy (SEM) tests were performed on specimens of concrete mixes before and after heating. It was found that in specimens with high binder content (1400 kg/m3), replacing 50% silica sand with GW (GW/Agg = 50%) in refractory concrete improves compressive and flexural strengths by 3–15 and 4–24% before heating, respectively. It was also shown that using GW to replace silica aggregates in concrete specimens with a 1200 kg/m3 binder content not only did not undermine, but also improved the compressive and flexural strengths of refractory concrete after heating by 20–78% and 15–60%, respectively, as a result of sintering. Meanwhile, in the case of the concrete with 1400 kg/m3 binder content, adding GW exacerbated its loss of compressive and flexural strengths after heating due to little or lack of sintering.

Refractory concrete based on high-alumina cement and clinker aggregate

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Experiment Planning for Prospective Use of Barium-Containing Alumina Cement for Refractory Concrete Making

The prospect of further use of refractory concrete based on barium-containing alumina cement was justified, with the help of a simplex-lattice method of the experiment planning, the granulometric composition of concrete was selected and its physical, mechanical and technical properties were determined, which exceed the properties of the used analogues.

Evaluation of the Addition Refractory Waste as Aggregates in Concrete for Impeller KR

Refractories, materials used in steel works, are directly or indirectly, associated with a very wide range of environmental problems. When discussing the influence of refractories on the environment, one should consider: aspects related to the global environment, local environment, work environment and the generation of waste. Refractory wastes are historically disposed of as waste in industrial landfills. However, some of the refractory materials used have the potential to be recycled, contributing to environmental and economic sustainability. The addition of recycled aggregates in refractory concrete used to molded Impeller KR was evaluated for the development of refractory recycling technology after use. In general, the results of the dynamic slag test and industrial test indicated the potential of the use of recycled aggregates slide gate.

Investigation of the influence of granulometric composition of the aggregate and the content of the binder on the properties of refractory concrete

Depending on the additives used, refractory concretes acquire the necessary properties: fire resistance, porosity, heat resistance, maximum application temperature, etc. The influence of the granulometric composition of the mullite aggregate and the content of the binder (cement) on the properties of refractory concrete was evaluated. MLS-62 was used as a filler (the content of the determining component Al2O3 was more than 62%), and Secar 71 high-alumina cement was used as a binder. To test the samples obtained from different granulometric compositions, the mullite aggregate was sieved in fractions (–6+3) mm, –3 mm. In the developed compositions of refractory concrete, these fractions were mixed in different percentages:(–6+3)/(–3). The cement content in the compositions varied by weight: 15%, 20%, 25%. The study was carried out in the factory laboratory, where samples of refractories of all the compositions were made by vibration pressing method. The resulting samples were dried at 110 °C and fired. It was found that after drying, samples with a cement content of 25% had the highest strength indicators content of 25% was the best result in terms of strength and shrinkage. Studies of the impact of the granulometric composition of the charge on the physical properties of refractory concrete showed that the highest strength indicators were exhibited by samples of refractory concrete with a percentage of fractions in the aggregate of 40/60 and 20/80, as well as with the highest amount of cement content in the composition – 25%.After firing at 800oC and 1300oC, the strength of the samples decreases. It was shown that the reason of this phenomenon was softening, mainly associated with dehydration of the binder. The refractory concrete obtained with the use of aggregate with a fractional composition of 20/80 and a cement.

Self-Excited Acoustical System Frequency Monitoring for Refractory Concrete under Uniaxial Compression

The characterization of materials, stress and fatigue state monitoring based on the acoustoelastic principle are gaining widespread attention in recent years, mainly due to their advantages such as high sensitivity and non-destructive character. This article presents the application of a non-destructive acoustic method to test the degree of degradation of materials with which the heating boiler is coated. The combustion chamber is covered in materials when the temperature of the process itself increases, and has a very positive effect on fuel combustion. Unfortunately, with the passage of time, such materials undergo gradation. This article describes an innovative measuring system that has been successfully applied to monitor changes in resonance frequency under uniaxial compression in refractory grade material, which by definition is characterized by a high level of heterogeneity with a network of pre-existing cracks. The paper indicates that both stress and elasticity coefficients have an impact on the vibration frequency of the measuring system. Initial research was conducted to qualitatively determine the influence of these parameters on the measured frequency of the system.