Effect of filler-ash on the properties of epoxy resin composite

. At present in Russia a huge amount of ash and slag waste from thermal power plants is accumulated in dumps and heaps. For several decades the problem of utilisation of non-combustible residues generated during coal combustion has been studied. These wastes are unfavourable for the environment due to toxic substances and heavy metals in their composition. Ash and slag waste is a type of waste generated during combustion of coal with high ash content in the boiler at thermal power plants. The use of ash as a filler in thermal insulation material not only reduces the cost of scarce and expensive materials, but also increases the strength characteristics of the composite material. This paper deals with the method of ash utilisation, use of ash as a filler component in composite material. The aim of the study is to develop the composition of insulation of pipelines and their tensile strength tests. The task is to test prepared specimens of glass fibre, epoxy resin, hardener and ash under tensile strength on a universal testing machine REM-A.


Introduction
Composites are materials consisting of two or more components (reinforcing elements and binding matrix) and possessing properties different from the total properties of the components.Thus, practically all materials known in nature, such as wood chips, shredded plastic, foam plastic and others, can be used as filler.In all cases, special requirements are imposed on the materials used for the production of composites.Sufficiently important parameters are strength, durability, ease of manufacture and cost of the product.Composites compete effectively with such structural materials as aluminum, titanium, steel.Industries actively using composite materials include aviation, astronautics, ground transport, and chemical engineering.Composites are used for production of automobiles, railway transport objects, aircrafts, rockets, submarines, tanks for storage of various kinds of liquids, pipelines.Materials, the development of which was initially carried out under the orders of military departments, primarily for application in aircrafts, are implemented in many branches of civil industry.As a rule, the cost of composite materials is high, which is connected with the complexity of technological processes, high price of used components.However, there is a possibility of saving expensive components by using fillers from secondary products such as ash.Ash by its origin is a mineral waste.In turn, mineral wastes are close to natural raw materials in their technical properties, composition and performance characteristics.Their use in production is one of the main directions of reduction of material intensity of production [1][2].
The integration of fly ash into composite materials represents a promising approach to further improve the efficiency and environmental sustainability of production.As a mineral waste, fly ash has the potential to become a valuable secondary filler that can significantly reduce the cost of expensive components such as polymers and reinforcements.This is an important solution in the context of striving for sustainable resource utilisation and reducing environmental impact [3].
The use of ash in composites, apart from its economic benefits, also helps in solving the problem of waste utilisation.Fly ash, due to its technical characteristics and proximity to natural raw materials, can be effectively integrated into the matrix of composites, enriching their properties and imparting additional functional characteristics [4].
It should be noted that the incorporation of fly ash into composites requires careful research and optimisation of mixing and processing processes to achieve the best results.This approach may prove to be key for further development of composite technologies and their application in various industries [5].
In addition to sustainability and economic benefits, the integration of fly ash into composite materials also contributes to reducing the burden on the environment.Reducing the consumption of primary resources and utilising secondary products such as fly ash helps to reduce emissions and waste disposal, making an important contribution to the overall sustainability of industrial processes [6].
This innovative approach can also open new horizons for creating lighter, stronger and more functional composite materials.Ash, due to its nature and chemical composition, can add unique properties to the materials, which can broaden their applications.For example, the introduction of ash can enhance the thermal insulation or sound insulation characteristics of composites, which will open up new opportunities in the construction and automotive industries [7].
Given the growing interest in sustainable solutions and material innovation, the integration of fly ash into composite materials is an important step forward.This approach can be an example of how the combined use of technological expertise and natural resource knowledge can lead to a more sustainable and efficient industry [8].
Parallel to the positive aspects of integration of fly ash into composite materials, some challenges should be considered.The effects of ash on the physical and mechanical properties of composites need to be thoroughly investigated.New processing methods may need to be developed and manufacturing processes may need to be adapted to efficiently mix and distribute the ash in the matrix [9].
It is important to recognise that the chemical and physical properties of ash can vary depending on the source and composition, so accurate data is required to ensure stability and reliability of the final materials.Processing and mixing processes can also affect the uniform distribution of ash in the matrix and therefore the final material properties [10].
The future of the integration of fly ash into composite materials depends on co-operation and research between different areas of science and industry.However, with the right approach, it can lead to more sustainable, efficient and functional materials that can find applications in many sectors, from construction to vehicle manufacturing [11].
A better understanding of the use of fly ash in composites may also contribute to innovative developments in industrial waste management.The integration of fly ash into composites could provide evidence that by-products can be reconceptualised as valuable resources, reducing waste and environmental impact [12].
Collaboration between research, engineering and industry should be actively promoted to develop new methods of ash processing and optimise its interaction with other components of composites.Continued research will reveal the potential of ash to improve a variety of material properties, from mechanical to thermal insulation [13].
The main success factor in this direction is the close co-operation between the fields of science, industry and regulation.The introduction of new ash-based technologies can be an important step towards a more sustainable and innovative future industry, contributing to the balance between human needs and environmental conservation [14][15].

Production of fibreglass plates
The mixture of epoxy resin, hardener and petroleum coke was prepared according to the technical specification.For the preparation of four plates (Samples 1-4) consisting of four layers of glass fabric, 16 plates (width 300 mm and length 100 mm) were made, then the prepared compound was applied to each layer.For durability tests, 4 plates with different composition of compound mixture were prepared according to The fabrication process of glass fibre reinforced plastics based on glass fabric and compound mixture is presented below (fig. 1

Tensile testing of fibreglass plates
The tests were carried out on a universal testing machine REM-A (fig.2):   The optimisation problem allows to determine the exact value of ash fraction in the composite material, which is Δ = 48%, and allows to reach σ = 206 MPa, which is 1.51 times higher compared to the initial sample.Ash in this system is a filler, and epoxy resin with hardener is a binder.Thus for realisation of manufacturing technology it is possible to use the range of ash share in composite material 44-53% that will simplify the technology and will allow to reach maximum values of strength limit.

Conclusion
On increasing the amount of ash in the composite material, the tensile strength increases up to values of 48 % ash fraction in the specimen.With further increase in ash fraction, the tensile strength starts decreasing.The increase in strength with change in ash fraction in the samples is probably due to the transition of the binder into a system of thin films surrounding the filler particles.
The contact between ash (filler) particles when its content increases above ~ 50 % leads to a drop in tensile strength.The key role in providing strength of composites is played by the adhesive strength of the filler-binder matrix bond.
Filler particles are stress concentrators and therefore, when their content in the matrix reaches a certain value, it can lead to embrittlement of the composite material, which is also confirmed by a decrease in the maximum strain.However, this effect may not be observed in specimens with reinforcing fibreglass plates.

Fig. 1 .
Fig.1.Manufacturing process of glass fibre reinforced plastics based on glass fabric and compound mixture: a) glass fibre blanks for preparation of fibreglass plates; b) mixing process; c) prefabricated fibreglass plates

Figure 3 Fig. 5 .
Figure3shows the graphs of maximum disturbance dependence on time obtained by the system software of the REM-A device during the test.

Table 1 .
Table No. 1. Data on the composition of injection moulding compounds for the preparation of glass fibre reinforced plastics Workflow for testing fibreglass platesThe results of the measurements are presented in Table No. 2.

Table 2 .
Measurement results of tensile strength of composite materials