Study of the Properties of Modified Concrete Containing Various Types of Fibers and Fly Ash

The article researches the properties of modified fine-grained concrete containing different types of fibres and fly ash. The effect of different types of fibres on the flexural and compressive strengths and shrinkage deformations of concrete modified with polycarboxylate superplasticiser was investigated. The results showed that the use of straight long steel and polymer structured fibres made it possible to obtain composites with increased flexural strength.The study shows that in order to achieve high flexural strength and low shrinkage in cement concrete with high-strength fly ash matrices, it is necessary to combine steel and polymer fibres. The combined addition of SA l/50 + PMS l/50 fibres to the modified concrete with a content of 40% by mass of fly ash provides an increase in flexural strength by 23.9-18.0% at all curing times. It was found that the addition of 40% by mass of fly ash can reduce the shrinkage deformation of modified fibre-reinforced concrete of all compositions. The modified fibre-reinforced concrete with FA is characterised by a dense meso- and microstructure. The introduction of PCE and an increased amount of fly ash provides a dense contact zone between the cementitious matrix, fibre and aggregate. The use of fly ash in modified fibre-reinforced concrete provides technical, economic and environmental effects in construction.