Industrial experience in the implementation of clinker-free binders of alkaline activation

Objective. Issues related to the search for new, less energy- and material- intensive binders have long been on the agenda of many world environmental forums, since the carbonate technology of Portland cement entails pollution of the surrounding atmosphere and habitat, and the price of this product is unjustifiably growing. In our opinion, alkaline cements could contribute to the construction industry. Within the framework of this work, research results have been obtained that confirm the effectiveness of the development of a clinker-free technology for producing alkaline-mixed binders and composites based on them using aluminosilicate additives, both natural and technogenic origin.Method. The methods of electron microscopy and differential thermal analysis make it possible to study the nature of the components and the processes of formation of the structure of the cement stone. Waste from the cement industry has the appropriate granulometric and chemical composition, the aluminosilicate mineralogy of the studied powders confirms their compliance with the ready-made raw mix of Portland cement clinker, which is the key to the possibility of their effective use.Result. The carried out differential thermal analyzes confirmed the presence of the following phases in the composition of cement stone on binding bonds "cement dust - alkaline activator" of zeolite, calcite, mica type muscovite, montrillonite, magnesium oxide, calcium sulfoaluminates, ettringite structure, calcium hydrochloraluminate, calcium hydrosilicate, calcium hydrosilicate calcium.Conclusion. The obtained regularities of the processes of formation of the structure of the cement binder "waste of the cement industry - Na2SiO3", will transform these developments to create strong and durable artificial building composites competing with concretes on Portland cement.

Technological solutions for well construction in high-viscous shale hydrocarbon fields

The article discusses the main technological processes of well construction for the production of high-viscosity hydrocarbons from productive lowporosity reservoirs with high temperature and pressure conditions, which include shale deposits of Bazhenov formation. According to the results of the review and analysis of existing solutions in the development of this deposits, the following measures were justified and proposed: construction of branched multi-hole azimuth horizontal wells, implementation of selective multi-stage hydraulic fracturing in the productive formation; the use of oil-based process fluids when opening the reservoir, the use of plugging materials for isolation of the reservoir, the hardening product of which is represented by thermally stable hydrate phases (hydrobasic hydrosilicates). Вranched wells have a long horizontal end (about 1 000 meters or more). Only a part of the horizontal section works effectively, which is the basis for the development and application of the staged, both in time and along the strike, hydraulic fracturing method. At the level of the invention, a method and apparatus for carrying out multistage selective hydraulic fracturing in wells with horizontal completion have been developed. The article describes a method for implementing multistage selective hydraulic fracturing, comparing this method with the existing ones. Much attention is given to the need to use hydrocarbon-based solutions for the initial opening the reservoir, to use cement slurries from composite materials to separate the reservoir, the hardening product of which is a stone formed by low-basic calcium hydrosilicate.

The Economic Efficiency of the Development of Dry Mixes with the Supplement Based on Calcium Hydrosilicates

Provides information about the effectiveness of the introduction of modifying supplement in the formulation of dry mixes. Presents information about the technology of synthesis of supplement based on calcium hydrosilicates. It is established that the supplement has a high activity. A recipe for a lime dry mixes is presented using a supplement based on calcium hydrosilicate, synthesized in the presence of diatomite. The economic efficiency of the developed dry mixes with the use of calcium hydrosilicates has been calculated.

Synthesis of Supplement Based on Calcium Hydrosilicate for Dry Mixes

Using of supplement based on calcium hydrosilicates as structuring supplement in dry mixes lime is proposed. It shows the impact of supplement synthesis mode on the structure formation of calcareous compositions. The efficiency of the using of modifying supplements of amorphous silica, such as diatomite, in the synthesis is shown. It has been established that in supplement of calcium hydrosilicates synthesized with diatomite a greater amount of calcium hydrosilicates, belonging to low-basic ones, are contained. X-ray analysis of samples based on synthesized supplements is presented. A high activity of synthesized calcium hydrosilicates had been established. It has been established that the injection of supplements of hydrosilicates accelerates the gain of mechanical strength. It is shown that the injection of supplements of hydrosilicates accelerates the increase of water resistance and frost resistance of coatings. The operational properties of coatings based on the developed dry mix with the addition of calcium hydrosilicates synthesized with diatomite are presented.

Effect of mineral additives on structure and properties of concrete for pavements

Concrete pavements is an attractive alternative to asphalt pavements because of its lower cost and higher durability. Major contribution to sustainable development can be made by partial replacement of cement in concrete pavement with supplementary cementitious materials of different nature and origin. In this paper, the effect of natural zeolite and perlite additives in complex with chemical admixtures on the structure and properties of concrete for pavement was studied. Compressive and flexural strength test was used to study the mechanical behavior of designed concrete under load. Generally, the compressive strength of both control concrete and concrete containing mineral additives levels at the later ages of hardening. The microstructure analysis of concrete with mineral additives of different nature activity showed the formation of additional amount of hydration products such as tobermorite type calcium hydrosilicate which provide self-reinforcement of hardening concrete system.

Design of rapid hardening engineered cementitious composites for sustainable construction

This paper deals with design of environmentally friendly Rapid Hardening Engineered Cementitious Composite (RHECC) nanomodified with ultrafine mineral additives, polycarboxylate ether based superplasticizer, calcium hydrosilicate nanoparticles and dispersal reinforced by fibers. The incremental coefficient of surface activity was proposed in order to estimation of ultrafine supplementary materials (fly ash, methakaolin, microsilica) efficiency. A characterization of RHECC’s compressive and flexural properties at different ages is reported in this paper. Early compressive strength of ECC is 45-50 MPa, standard strength – 84-95 MPa and parameter Rc2/Rc28 – 65–70%. The microstructure of the cement matrix and RHECC was investigated. The use of ultrafine mineral supplementary materials provides reinforcement of structure on micro- and nanoscale level (cementing matrix) due to formation of sub-microreinforcing hydrate phase as AFt- and C-S-H phases in unclinker part of cement matrix, resulting in the phenomena of “self-reinforcement” on the microstructure level. Designed RHECC may be regarded as lower brittle since the crack resistance coefficient is higher comparison to conventional fine grain concrete.

The Effect of Particle Size Distribution of Lime on Properties of the Autoclaved Calcium Hydrosilicate Materials

This investigation was made to examine how the particle size of lime influence the properties of calcium hydrosilicate materials. Quicklime was sorted in three fractions: 0-1 mm, 1-11.2 mm and 11.2.-22.4 mm. Slaked lime putties were prepared in the laboratory by mixing lime fractions and deionized water under vigorous stirring. The C/H ratio was 1:8. The lime putties were mixed with finely ground sand with the C/S ratio equal to 0.85. The hydrosilicate materials were prepared under hydrothermal conditions: temperature 205 °C, pressure 16 bar. This work focuses on lime putty rheological behaviour and on composition and properties of lime hydrosilicates. It was found that hydrated particles of fractionated lime form smaller aggregates than standard lime. Plasticity increases with the increasing size of fraction. When separate fractions are used, 11.3 Å tobermorite crystallization is slower.