Development of alkaline concrete on the basis of active aggregates

The object of the research is the process of directed structure formation in the body of alkaline concrete, made using a reactive aggregate, in this case, basalt, and the process of deformation development in such concrete. The problem with using reactive aggregates is that they cause alkaline corrosion. It manifests itself in the form of cracks and layers of gel-like substances that form at the point of contact of the aggregate with the cement stone. During the research, methods of physical and chemical analysis were used (X-ray phase, differential thermal and thermogravimetric analyzes, electron microscopy, infrared spectroscopy, microprobe analysis). And also methods of mathematical planning of experiments have been used for the dependence of the physical and technical properties of cements and the directions of their structure formation. Also, the research has been carried out based on the analysis of world achievements in solving the problem of alkaline corrosion of concrete. The possibility of joint operation of the matrix of alkaline cements and active aggregates, represented by basalt, has been determined. The component composition of alkaline cement has been optimized and the need to increase the amount of the alkaline component in the system for the normal course of structure formation processes has been proved. The study of the influence of technical factors and conditions of hardening on the development of processes of structure formation of the investigated compositions has been carried out. The deformation properties of fine-grained concrete based on slag-alkaline cement and basalt aggregate have been investigated. It is shown that the expansion deformations of the samples, which accompany the process of alkaline corrosion of the aggregate in concrete, are directly related to the component composition and hardening conditions of the material. The obtained research results confirm the possibility of using active aggregates for the manufacture of building materials, in particular, based on alkaline cements. But for the safe course of the processes of structure formation, the component composition of the system has to be adjusted by introducing an active mineral additive and an additional alkaline component. The use of hydrophobizing additives makes it possible to increase the strength of the material even when operating under normal heat and humidity conditions.

STUDY OF DEFORMATION PROPERTIES OF ALKALI ACTIVATED CONCRETES USING ACTIVE AGGREGATES

Results of study of deformative properties of fine-grain concrete are shown using slag alkali activated cement and active aggregate, represented by fraction 0-2.5 mm. It had been shown that expansion deformations of concrete specimens, supplying process of alkaline corrosion of aggregate in concrete, directly combined with component composition and conditions of hardening and storing of material. Thus, it was show, that using alkaline component in the state of dry salt (sodium carbonate) shrinkage/expansion deformations are varying in the shorter ranges comparing to alkali activated concrete with the alkaline component represented by soluble glass. Introduction of active mineral admixture represented by metakaolin also leads to the decreasing of deformations comparing to the compositions without such admixture. Different conditions of hardening and storing of the specimens are also influence well on the development of shrinkage deformations. It is shown that drying of specimens with active process of alkaline corrosion of concrete makes it possible to stop development of expansion deformations in concrete. Hydrophobization of the dried specimens make it possible to store for some time linear characteristics of concrete specimens. This opens the possibility to store lifeability and exploitation terms of construction with destructive corrosion processes in concrete without spending significant costs and without canceling of construction exploitation. Hydrophobization of specimens without drying leads to the intensification of structure formation processes and higher rates of development of shrinkage/expansion deformations. That means, that traditional method of protection of concrete constructions (covering of concrete constructions by painting materials) is not able to prevent, but also possible to activate development of destructive processes of alkaline corrosion of concrete, becoming dangerous to be used.

Analytical Method Development and Validation of Etravirine by RP-UFLC

An ultra-fast liquid chromatography (RP-UFLC) approach was processed for the estimation of ETR, which is quick, responsive, reliable, and inexpensive. Work on the Phenomenex Kinetex C18 column (250x 4,6mm. 5μ) was carried out with MeOH and acetonitrile in the mobile phase ratio of (60:40v/v) at 1.0mL/min. With a PDA detection system, the eluent was tracked at 311nm. ETR elutes at a persistence time of 3.226 min. The proposed method gives linearity of concentration from 1 to 5μg/mL, with the value of R2 at 0.9942%. For the proposed method, LOD and LOQ are measured as 0.02 and 0.073μg/mL. The pharmaceutical drug included acidic, alkaline, corrosion, Ultraviolet, and heat stress stipulations. The deterioration material was nicely resolved from ETR peaks, which showed the reliability of the process. The approach has been tested with respect to process adequacy, linearity, reliability, and robustness, as per ICH guidelines.

Humidity deformation of concrete subjected to alkaline corrosion. The process model

The article presents an analysis of works on alkaline corrosion of cement concrete. It is shown that of particular interest are works that analyze the effect of concrete cracks, which appeared during operation, on the intensity of such corrosion. A model of changes in volume deformations of concrete samples has been developed, which is based on the phenomenon of technogenic metasomatosis involving chemical and physical-chemical processes leading to the transformation of the parameters of the structure and composition of the material under the influence of the external environment. An analysis of the model is carried out and the consequences are formulated, the fixation of which in experimental studies will make it possible to identify the course of technogenic metasomatosis in concrete.

Moisture deformation of concrete subjected to alkaline corrosion. Experimental results

The authors present the results of the study of concrete core samples extracted from the concrete coating of the airfield that was exposed to alkaline corrosion. It is shown that by the nature of the volumetric deformation kinetics, concrete samples can be classified into three groups: samples mainly subjected to swelling; samples mainly subjected to shrinkage; samples that have a marked technogenic metasomatosis. The experimetal investigation results have confirmed the theoretical conclusions drawn on the base of the technogenic metasomatosis model. There have been revealed the facts of latent technogenic metasomatosis, confirming its prevalence in concrete products. The study of volumetric deformation of samples during their exposure to various media provides additional information for assessing the material`s durability: the ascertained deformation of the samples is the evidence of the exchange processes that will reduce the operation properties of the material with an intensity increasing over time.