Lime-based mortars with various binder composition: characterization and freeze-thaw resistance assessment

The study focused on lime mortars with different lime binder types regarding the frost attack effects on their microstructure and mechanical characteristics. The performances of studied mortars in hardened state was significantly influenced by the amount of mixing water and by curing conditions. Inhomogeneous microstructure was observed inside the 360 days old specimens with dimensions 40 × 40 × 160 mm in the case of all lime mortars types. The different state of the binder hardening with respect to various distances from the specimen surface and the different behaviour of matured outer part and immature inner part of lime mortar specimens influenced performed tests and reflected in all results. After 10 and 20 freeze cycles, respectively, the compressive strength of all lime mortar specimens with the hydraulic binder component increased, indicating a beneficial effect of the water on the hydration previously unreacted hydraulic binders. On the other hand, the flexural strength of the frost-aged specimens decreased significantly, indicating the drastic procedure of the test performed concerning lime mortars characteristics, especially when the pure air lime binder was used. Improvement of the testing procedure especially for lime mortars, which are characterized by slow hardening, was recommended.

Solid Fuel Based on Waste of Low-Utilized Combustible Energy Resources

The paper presents main trends in growth and generation of waste, depending on increase of world GDP and the population of the planet. The main directions in extending the concept of national strategies for sustainable development have been considered with due account of energy and resource conservation problems, as well as the need for the rational use of natural and secondary resources in all countries of the world community. The energy potential use of combustible waste that has not found technological application is considered by many countries as one of the priority areas in the field of unconventional energy. The paper describes the main directions in application of the technology for briquetting multicomponent compositions into solid fuel. The developed production technology makes it possible to process waste products by briquetting them with the addition of various binders, and on the example of a binder component in the form of viscous hydrocarbon-containing waste, the main technological features of obtaining solid multicomponent fuel are presented in the paper. The paper describes the equipment for electrohydraulic treatment, which operates as a part of the preparation line for briquetting of the applied oily waste and that allows to reduce the sulphur content in the waste used, and such approach in general permits to regulate the environmental characteristics of harmful substance emissions at the maximum acceptable level. Taking into account the application aspects of the technology for wet briquetting of materials, the paper reflects the main results of the obtained dependences of humidity on productivity according to the content of the binder component. The proposed algorithm for solving the problem makes it possible to rationally use of substandard combustible industrial waste to obtain a multicomponent solid fuel, while at the production stage, the energy and environmental aspects of the resulting fuel are taken into account with due consideration of the component composition of the fuel.

Polyvinylidene Difluoride: A Universal Binder for Preparation of Solid Phase Microextraction Devices

<p>The communication describes the application of a fluorocarbon-based polymer as a high performance binder component for coatings suitable for a variety of solid phase microextraction (SPME) configurations. SPME devices are characterized by their ability to perform physicochemical extraction of chemical compounds from a given sample, rending said chemical compounds suitable for instrumental determinations; fundamentally speaking, physiochemical extraction is accomplished by thermodynamic equilibrium driven by diffusion and partitioning of chemical compounds. A polyvinylidene difluoride (PVDF) polymer was used to immobilize various sorbent particles on different supports to create different formats of SPME, namely fiber, thin-film membrane, and CBS devices. In this report, PVDF-based coatings are introduced as universal SPME coatings that are amenable to both gas chromatography (GC) and liquid chromatography (LC) while also improving the physical stability of the resulting device, in addition to eliminating the need for highly toxic reagents associated with the preparation of fully fluorinated based coatings previously reported in the literature. Additional incorporation of other polymers to increase coating porosity as well as the adhesion of PVDF on metal surfaces is also described.</p>

Polyvinylidene Difluoride: A Universal Binder for Preparation of Solid Phase Microextraction Devices

<p>The communication describes the application of a fluorocarbon-based polymer as a high performance binder component for coatings suitable for a variety of solid phase microextraction (SPME) configurations. SPME devices are characterized by their ability to perform physicochemical extraction of chemical compounds from a given sample, rending said chemical compounds suitable for instrumental determinations; fundamentally speaking, physiochemical extraction is accomplished by thermodynamic equilibrium driven by diffusion and partitioning of chemical compounds. A polyvinylidene difluoride (PVDF) polymer was used to immobilize various sorbent particles on different supports to create different formats of SPME, namely fiber, thin-film membrane, and CBS devices. In this report, PVDF-based coatings are introduced as universal SPME coatings that are amenable to both gas chromatography (GC) and liquid chromatography (LC) while also improving the physical stability of the resulting device, in addition to eliminating the need for highly toxic reagents associated with the preparation of fully fluorinated based coatings previously reported in the literature. Additional incorporation of other polymers to increase coating porosity as well as the adhesion of PVDF on metal surfaces is also described.</p>

Briquetting of Wastes from Pulp and Paper Industries by Using AOD Converter Slag as Binders for Application in Metallurgy

A number of carbon-rich (containing up to 47 wt% C) and lime-rich (containing up to 96 wt% of CaO-compounds) waste products from the pulp and paper industries can be used in iron and steel industry as fuels and slag formers for various metallurgical processes such as blast furnaces (BF), cupola furnaces (CF), argon oxygen decarburization (AOD) converters and electric arc furnaces (EAF). In most cases, these wastes consist of different size powders. In order to facilitate loading, transportation and charging of these powder wastes, briquetting is required. In this study, a pulverized AOD slag was tested as a binder component for briquetting of CaO-containing wastes (such as mesa, lime mud and fly ash) from pulp and paper industries. Moreover, mechanical testing of the possibilities for loading, transportation and unloading operations were done, specifically drop test trials were done for briquettes with different chemical compositions and treatments such as heating and storage. The results showed that an addition of 10–20% of AOD slag as a binder component followed by heat-treatment at 850 °C significantly improved the mechanical properties of the CaO-containing briquettes. An application of these briquettes will significantly reduce the consumption of natural resources (such as nature lime) in the metallurgical processes. Moreover, it can reduce the landfill area of wastes from pulp and paper industries, which is important from an environmental point-of-view.

Effect of SRA on the Course of Hydration of Cement Composites

Cement hydration is a chemical reaction that is associated with the development of hydration heat and changes in the volume of input components that transit from the solid and liquid phase to one homogeneous whole. In order to eliminate the volume changes already occurring during the hydration process, several principles can be applied, such as the use of active or inert admixtures as partial cement substitute or special shrinkage reducing additives. The experiment verifies the effect of anti-shrinkage additives on the course of hydration of cement pastes in terms of the development of hydration temperatures and elimination of volume changes of cement pastes. Volume changes will be monitored for the first 30 hours of cement mixing with water, i.e. in the time when the major changes occur due to this chemical reaction. Due to the expected hydration deceleration of the binder component by the effect of SRA, the impact of the use of these additives on the curing time of the composite and consequently on the mechanical parameters of the concrete will be verified.

Improvement of Arbolit Concrete Bio-Resistance with Additives by Nanomodificators

Arbolit concrete, as one of the types of light modern concretes, is a complex composite of a combination of different materials: a binder component, additives and cellulose aggregate. Wall blocks, panels, slabs, etc. are manufactured from arbolit concrete for the construction of low-rise residential, public, industrial and agricultural buildings. According to the properties, arbolit concrete is closest to the tree (organic aggregate is more than 85% of the volume). Arbolit concrete combines the best qualities of wood and concrete: environmental friendliness and durability of concrete, strength of wood and its vapor resistance. However, cellulosic aggregate has its own specific features that negatively affect the structure formation processes, in particular, the strength and durability of the composition “ organic aggregate - astringent "to moisture-variable effects. Selection of a binder for arbolit concrete is also a difficult task that requires a separate research. Basically, for the manufacture of products made of arbolit concrete portland cement is used, abroad - lime binder. The disadvantage of cement concrete on cement, lime and lime containing a binder is a relatively long period of gain of brand strength. A promising direction for solving this problem is the use of composite gypsum binder for the production of concrete. Based on the above, we can conclude that the design of low-density arbolitbeton formulations on a composite gypsum binder is an urgent task [1].