fly ash

A new competitive class of grouting materials has been created. These lightweight grouting materials (LGM) with a density of 1370–1650 kg/m3 consist of oil-well Portland cement PCTI-100, fine powder of PE grade (a by-product of fireclay production from kaolin), acidic fly ash from state district power plants, and lime dust (a by-product of lime production). The composition of the products formed during LGM hydration was clarified by X-ray phase and differential thermal analysis.

The European Green Deal is the latest climate and environmental protection program launched by the EU. This is a strategy to transform the EU into a resource-efficient economy, in which in 2050 there will be zero greenhouse gas emissions and economic growth will be decoupled from the use of natural resources. After approving the National Economic Strategy for the period until 2030, Ukraine joins and focuses on the European Green Deal and aims to achieve climate neutrality in 2060 (Natsionalna ekonomichna stratehiia, 2021).

The article presents the peculiarities of obtaining superplasticized cementitious systems "Portland cement – fly ash - superplasticizer" to find a rational provision of the given construction and technical properties of concrete. It was studied the physico-chemical peculiarities of the hydration processes of superplasticized cementitious systems. There were solved problems of directional formation of the microstructure of cement stone.

A new competitive class of plugging compositions (weighted non-shrink plugging materials) has been created using as components a fly ash from thermal power station, a weighting additive and a superplasticizer. X-ray phase analysis identified the composition of new materials formed in the hydration process of the developed plugging compositions. The kinetic curves of the plugging material expansion in a wide temperature range have been obtained.

The development of high-performance materials, which are characterized by high compressive and flexural strength, durability and performance properties, is an urgent problem of modern construction. Engineered cementitious composites are one such material. Improving of properties of composites is achieved by partial replacement of cement with supplementary cementitious materials. The ratio of binder and filler components and superplasticizer consumption were selected.

The paper presents the results of research concerning the peculiarities of modern High Performance Concretes based on cementitious systems "Portland cement – active mineral additives – micro fillers – superplasticizers – accelerators of hardening". Physico-chemical regularities of structure formation of super plasticized cementitious systems are established.

In the article the features of reinforced concrete hardening at different temperature conditions and the current issues of preparation technology of Self-Сompacting Сoncretes (SCC) on the basis of superplasticized cementitious systems, combining knowledge of structure and modifying Portland cement compositions "Portland cement – active mineral additives – microfiller – superplasticizer – accelerator of hardening" to search for rational making provision of technical and building properties of concrete in the changing factors of its composition, technology and exploitation are shown.

The utilization of fly ash in concrete as partial cement replacement has many benefits. It leads to increase of a binder´s amount and improves workability (pumpability, keepability and others) of fresh concrete, as fly ash behaves as a solid fluidifier. Application of fly ash in combination with a fluidifier is very effective, because it improves the workability of fresh concrete significantly. Regarding characteristics of lower class fresh concrete the main benefit of fly ash utilization with fluidifier is complement of fine binder, especially particles up to 0,25mm.

The possibility of obtaining Self-Compacting Concrete with a large amount of supplementary cementitious materials, including fly ash is shown in this article. Research results of rheological properties of fiber reinforced Self-Compacting Concretes with high volume of fly ash and chemical admixtures, which regulate fluidity and viscosity of concrete mixes, are shown. It was established that the replacement of 55, 70 and 85 wt. % of binder with fly ash allows to obtain Self-Compacting Concrete mixes with the consistency class SF2, viscosity T500 = 5 s and the volume of entrained air 0,4 %.