Effect of electrolytes with multicharged cations on the strength of stone made of a modified mixed air binder

The possibility of obtaining mixed air binder of high strength and water resistance by using active mineral additives has been considered. In this work, the gypsum binder has been replaced by a combination of hydrated lime with active additives - metakaolin and granulated slag. The ratio effect of the silica component to the binder on the compressive strength of the stone was studied. According to the results of X-ray phase analysis, the presence of tobermorite-like calcium hydrosilicates and the absence of hydrate lime phase were diagnosed in the stone. The influence of electrolyte additives - salts with three-charged cations - on stone hardening kinetics is shown. Increase in the compressive strength of 28-day-old stone from the modified mixed air binder by 5% with the introduction of 1% of the binder mass aluminum sulfate in the mixing water was established. The use of FeCl3 solution for mixing the modified mixed air binder leads to a decrease in the compressive strength of the 28-day-old stone. The mixing of the modified mixed air binder with Al2(SO4)3 solution reduces the time of setting.

MODIFICATION OF CEMENTITIOUS MATRIX OF RAPID-HARDENING HIGH-PERFORMANCE CONCRETES

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. It is shown that the formation of secondary fine ettringite due to the interaction of active alumina with calcium hydroxide and gypsum in the non-clinker part of the binder because of the effect of "self-reinforcement" compensates for shrinkage and increases the strength of the cementitious system. The modification of the cementitious matrix makes it possible to obtain Rapid Hardening High Performance Concretes that provide early loading and turnover of the formwork of monolithic constructions.

Definition Of Puzzolanic Properties Active Mineral Additives In Portlandcement

The article presents the results of testing the use of Angren dry remote active ash and slag in Portland cement as an active mineral additive. It was found that Portland cement with the addition of Angren dry remote active ash and slag renders karrazastoy, ekanomet clinker and it is proved that hydro removed ash and slag (2011 year) does not recommend as an active mineral additive. Therefore, dry remote active ash and slag is recommended for use as an active mineral additive in the production of cement, improving its construction and technical properties. The possibility of using Angren dry remote active ash and slag as an active mineral component for producing cements with low corrosion resistance is shown. Angren dry remote active ash and slag contributes to the formation of the structure of the cement stone, increases its density and strength against aggressive ions, causing increased resistance in aggressive environments. And save up to 30% of cement. It has been established that Portland cement with the addition of Angren dry remote active ash and slag has an intensifying effect on the formation of clinker minerals. Therefore, the Angren dry remote active ash and slag is recommended for use as a mineralizing additive in the production of cement. Use of chemical industry waste with replacement of expensive natural production and consumption waste. At the same time, an environmental problem is being addressed.

Abrasive Wear Resistance of Concrete in Connection with the Use of Crushed and Mined Aggregate, Active and Non-Active Mineral Additives, and the Use of Fibers in Concrete

Virtually every concrete structure comes into contact with abrasive effects of flowing media or solids, which have a direct impact on the durability of concrete. An abrasive effect is most pronounced in transport or water management structures, and these structures are often designed for a significantly longer service life (usually 100 years). This research evaluates the influence of the filler component in terms of the type of aggregate and its mineralogical composition on concrete abrasion resistance. As part of the impact of the binder component, several concrete mixtures were produced using the same aggregate and maintaining the same strength class with the addition of different types of active and inert mineral additives. In other parts of the research, the effect of adding fiber reinforcement on the abrasion resistance of concrete was verified. Mutual connections and correlations in different age groups (7, 28 and 90 days) were sought for all obtained results. The abrasion resistance of the composite was monitored by using standard procedures, especially using a Böhm device. It was found that for good abrasion resistance of concrete, it is not necessary to produce concretes with high strength classes using often expensive mineral additives (microsilica) and quality aggregates, but the maturation time of the composite and its microstructure plays an important role.

FEATURES OF THE SELECTION OF THE RATIONAL STRUCTURE OF THE COMPOSITIONAL GIPS BINDER

the dynamically developing construction in the Russian Federation makes it necessary to expand the range of alternative types of binders and materials based on them. Such a binder is a previously developed composite gypsum binder (CGB), used for the production of materials of various functional purposes. The manufacture and use of CGB-based composites was made possible by studying the Portland cement-gypsum-water system, the stability of which is ensured by introducing an appropriate amount of active mineral additives that reduce the concentration of Ca(OH) 2 in the liquid phase of the hardening system and create the possibility of hardening under certain conditions without dangerous internal stresses. In this paper, we consider the possibility of using composite gypsum binder for fine-milled quartzitic sandstone crushing dropout and concrete scrap crushing dropout as an active mineral additive. Rational compositions of composite gypsum binder are developed and their basic properties are studied. The reasonable choice of the amount of active mineral additive allows optimizing the properties of the composite gypsum binder.

POSSIBILITY OF USING VOLCANIC ROCKS IN THE CEMENT INDUSTRY

В данной статье раскрываются особенности формирования структуры цементных композиций с применением активной минеральной добавки вулканического происхождения. Полученные ре цептуры композиционных цементов позволят получать высококачественные бетоны с классом прочности от В60 до В100, снижать нормальную густоту бетонных смесей на 2530, при этом подвижность смеси остается постоянной. Кроме того, применение данной разработки позволит повышать темпы набора прочностных показателей бетона, что дает вероятность отказа от тепло вой обработки и способствует получению необходимой для распалубки прочности за промежуток времени 1824 часов. Работа выполнена в рамках исследований по реализации научного проекта 1848-200001 Высококачественные бетоны с повышенными эксплуатационными свойствами на основе местного природного и техногенного сырья , получившего поддержку Российского фонда фундаментальных исследований (РФФИ). The article reveals the features of the formation of the structure of cement compositions using active mineral additives of volcanic origin. The resulting composition of composite cements will make it possible to obtain high-quality concrete with a strength class from B60 to B100, reduce the normal density of concrete mixtures by 2530, while the mobility of the mixture remains constant. In addition, the use of this development will allow increasing the pace of a set of strength indicators of concrete, which gives the probability of refusal from heat treatment and helps to obtain the strength necessary for stripping for a period of 1824 hours.

EFFECTIVE CELLULAR CONCRETE ON THE COMPOSITE GYPSUM BINDER

The dynamically developing construction of the Russian Federation makes it necessary to expand the range of alternative types of binders and materials based on them. Such binders include a composite gypsum binder used for the production of materials for various functional purposes. The manufacture and use of products based on composite gypsum binders is made possible by studying the Portland cement – gypsum – water system, the stability of which is ensured by introducing of an appropriate amount of active mineral additives. Such additives reduce the concentration of Са (ОН) 2 in the liquid phase of the hardening system and create the possibility of hardening under certain conditions without dangerous internal tensions. This article discusses the obtaining of effective cellular concrete on a composite gypsum binder. Cellular concrete surpasses some traditional materials in its structure, properties, methods of preparation, and they are universal in terms of operational properties. The possibility and expediency of using thin-ground concrete scrap as a mineral additive in the composition of composite gypsum binder for cellular concrete is established in the work. Thermal insulation and structural cellular concrete of D600 and D700 grades are obtained. It is revealed that the stepwise loading of the components of the concrete mixture with the initial introduction of a gypsum binder is rational.

Assessment of Reinforcement Corrosion in High-Filled Ash-Containing Concrete

Article considers ways to improve the durability and operational characteristics of reinforced concrete structures designed for railway transport by adding active mineral additives such as fuel ash and other chemical modifiers.

Estimation of Hydration Degree of Blended Cements with the Help of k-Values

The growing utilization of various mineral additives in the building industry has caused concern worldwide to reduce the emissions of carbon dioxide from Portland cement (OPC) production. The present paper is focused on the determination of the degree of hydration of blended binding systems based on Portland cement. Blast furnace slag, fly ash, and ceramic powder are used in the study; they are applied by 12.5 wt.% up to 50% of OPC replacement. The evolution of the hydration process is monitored using thermogravimetry in selected time intervals to determine the degree of hydration; its ultimate value is obtained from numerical estimation using the Michaelis-Menten equation. However, due to the application of active mineral additives, the correction in terms of equivalent binder is conducted. Corrected values of the degree of hydration exhibit good fit with compressive strength.

MODERN TECHNOLOGIES OF MATERIALS FOR PROTECTION THE WORKING SURFACES OF HYDROCLONE AGAINST WEAR

The article considers the process of portland cement production by wet process. Portland cement is a hydraulic binder that is produced by cement clinker, gypsum and additives. Calcium silicates are commonly used as additives. Portland cement production consists of following processes: crushing of clinker and gypsum stone; preparation of mineral additives (crushing, drying); grinding of clinker with active mineral additives and gypsum; storage, packaging and shipping the cement to consumer. Since grinding is carried out in a closed cycle, it is necessary to select the classifying equipment. For this purpose, an analysis is made, which reveals that the hydrocyclone is the most multi-purpose and less expensive in operation of classifying equipment. The study of the hydrocyclone design demonstrates a significant drawback in the form of increased wear of the hydrocyclone working surfaces, which has an impact on durability and work efficiency. The degree of wear the hydrocyclone surfaces depends on the nature of the pulp impact and the mechanical characteristics of material of the hydrocyclone working surface. This article is devoted to the study of the most popular and frequently used wear-resistant materials to protect work surfaces from wear.