Properties Of Fine-Grained Concrete Research Articles

Application of Blast Furnace Granulated Slag for Self-Healing Bio-Concretes

The properties of fine-grained concrete containing 20–80% granulated blast furnace slag and bacteria species Bacillus Subtilis have been studied. An assessment was made of changes in strength, self-healing of cracks using optical and electron microscopy and measuring the speed of ultrasound propagation perpendicular to the crack plane; composition and characteristics of the healing agent in cracks using X-ray analysis methods. Self-healing of cracks in concrete without bacteria occurred due to calcite deposition as a result of carbonation of portlandite during 50–65 cycles of humidification-drying, and in the presence of Bacillus Subtilis bacteria due to calcite deposition during their vital activity in 10–15 cycles. It is shown that the addition of granulated blast furnace slag slows down the crystallization of calcite, which forms a healing substance in the crack. It is assumed that the combined use of granulated blast furnace slag in dosages of 40–80% and Bacillus Subtilis bacteria in concrete structures operating under conditions of variable humidification can ensure the process of self-healing cracks and maintaining the strength of concrete in the long term due to simultaneous processes of strengthening the structure due to prolonged hydration of slag minerals and calcite deposition in cracks due to the vital activity of Bacillus Subtilis bacteria.

Influence of anthropogenic waste of different genesis on properties of fine-grained concrete

Introduction. The growing amount of stored waste from TPPs has a negative impact on the environmental and economic situation in Russia. The content of ash dumps leads to pollution of nearby areas and increase in energy prices. To solve this problem, it is proposed to use TPP waste as a component of solutions. Materials and methods. The equipment on which the experiment was performed is listed. For the test of compressive strength, the press TP-1-350 Universal was used. For the test of flexural strength, MII-100 machine was used. Specific surface area of TPP waste was determined on PSKh-12 device. The samples gained the strength in the chamber of normal hardening. The chemical composition of TPP waste was determined by the X-ray fluorescent method. Results. The experimental data on the strength of specimens with the replacement of part of the cement by waste thermal power plants of different genesis are presented. The part of the samples were cured under normal conditions, and part was subjected to heat and humidity treatment. Specific cement consumption per unit of compressive and flexural strength was calculated. Compressive strength of mortars with replacement of 20% of cement by Kuznetsky TPP ash makes it possible to obtain samples with strength by 8% less than the control sample under normal curing conditions. The use of acid ash from Omsk TPP and Kuznetsky TPP under heat and moisture treatment makes it possible to obtain the samples with compressive strength higher than the control sample up to 13%. The introduction of 30 % of the basic ash from Novosibirsk TPP instead of cement allows to obtain samples with compressive strength up to 46,55 MPa. The calculation of specific consumption of cement per unit strength showed that the use of the proposed compositions is more cost-effective than the control ashless sample up to 30%. Discussion and conclusions. It has been proved that replacement of up to 30% of cement by TPP wastes makes it possible to obtain mortars with strength not lower than that of the control cement sample. Depending on curing conditions and the type of used TPP waste it is possible to receive samples with compressive strength up to 46,55 MPa and bending strength up to 9,31 MPa. It was found that the use of heat and moisture treatment for the samples using basic ash does not give an increase in strength, compared to acidic ash.

ПОЛНОСТЬЮ РЕЦИКЛИРУЕМЫЕ ЗВУКОПОГЛОЩАЮЩИЕ ПАНЕЛИ ДЛЯ ШУМОЗАЩИТНЫХ ЭКРАНОВ

There are thousands of kilometers of noise protection screens around the world along roads, railways and near airports. The use of such screens poses some issues. Barriers often lack the required level of sound absorption and have low durability. Screens can be noise-absorbing, noise-reflecting or both. Sound absorbing materials are used to suppress noise at medium and high frequencies. For sound deadening at low frequencies, resonant absorbers are used; they are Helmholtz resonators combined into a single structure. When panels reach the end of their life cycle, they must be recycled. Separating wood, metal, fiberglass or rock wool slabs wrapped in fiberglass is not easy. The production of mineral fiber requires a lot of energy. A selection of materials has been proposed and the properties of fine-grained concretes for the further manufacture of a noise-protective panel have been investigated. The perforated front and blank rear walls are made of fine-grained basalt fiber-reinforced concrete reinforced with alkali-resistant basalt fibers. The results of studies of fine-grained basalt concrete confirmed the effectiveness of the combined use of basalt fibers and superplasticizer Master Glenium 115. The physical and mechanical characteristics of basalt fiber-reinforced concrete are increased by about 70–80 % compared to traditional concrete, which will further increase the durability of imitation noise protection panels.

Properties of fine-grained concrete containing fly ash and bottom ash

Properties of fine-grained concrete containing fly ash and bottom ash

Ensuring Strength of Fine Grained Concrete with Mixed Cement Binders

The article presents the results of the evaluation of the strength of fine-grained concrete of ordinary grades on mixed cement binders with ash and slag waste of thermal power plants. To ensure the required strength, the preliminary activation of the mixed binder was envisaged, which is one of the main techniques for reducing cement consumption. Experimental-statistical models of the strength properties of fine-grained concrete was obtained, which make it possible to predict the required strength with a minimum consumption of cement and the optimal concentration of ash in the binder.

ВЛИЯНИЕ МИКРОНАПОЛНИТЕЛЕЙ ИЗ ПРИРОДНОГО ВОЛЛАСТОНИТА НА СВОЙСТВА МЕЛКОЗЕРНИСТОГО БЕТОНА

The possibility of obtaining effective highly dispersed additives from natural wollastonite is substantiated and their influence on the properties of fine-grained concrete is investigated. On the basis of wollastonite, a complex micro-filler with particle sizes up to 100 microns was developed, obtained by joint grinding with quartz sand in a 3:1 ratio in a ball mill in the presence of an anionic surfactant naphthalene-formaldehyde type C-3 and a calcium stearate hydrophobizer technical C-17. A suspension of wollastonite with a modal particle diameter of 405 nm was obtained by pre-grinding wollastonite and anionic surfactant in a ball mill, with their further ultrasonic treatment in a bath-type activator. Mathematical models of the dependence of compression and bending strength on the content of the initial components are developed. It is established that the complex microfill leads to an increase in the strength of fine-grained concrete in bending by 2 times, in compression by 1.7 times with its content in the composition of fine-grained concrete in the amount of 10% by weight of cement. Wollastonite suspension increases the bending strength of fine-grained concrete to 3.1 MPa, compression to 57.8 MPa. The results of qualitative x-ray phase analysis showed that the total intensity of diffraction maxima of not fully hydrated alite C3S, belite C2S grains and their aggregates in cement stone with wollastonite decreases by 1.5-2 times compared to the control composition. This is most likely due to the amorphous nature of the wollastonite surface after grinding in a ball mill and ultrasonic dispersion in a bath-type activator. In addition, such particles are the centers of crystallization. Their needle-like shape contributes to the reinforcement of the structure by crystallizing new formations of cement stone.

Influence of Plasticizers on the Properties of Fine-Grained Polymer Concrete

Polymer concretes are used in construction, engineering, electrical and chemical industries. Polymer concrete mixes are characterized by low mobility mixtures, due to their high viscosity. It makes difficult to use them in the production of thin-walled and high-reinforced structures, monolithic floors, application of finishing and protective coatings and repairing of roads. The influence of additives of dibutyl-phthalate, chlorinated paraffin, technical glycerin and engine oil on the mobility of the concrete mix and the physical and mechanical properties of fine-grained concrete, based on polyester resin, was studied. For polymer concretes with different type and quantity of plasticizer the density and bending and compression strength were determined. To improve the workability of the concrete mix and obtain a polymer concrete with a homogeneous structure and high strength, it is recommended to use chlor-paraffin ChP-470A and “Lukoil” engine oil as a plasticizer.

Properties of Fine-Grained Concrete with Admixture of Diatomite Powder

The paper reports on the experimental assessment of the physical properties of fine-grained cement-based composites whose composition was enriched with admixture of diatomite powder. Diatomaceous earth, due to its origin and availability, represents highly valuable low cost material that can dispose with high pozzlanic activity. On this account, it can help to mitigate the quantity of used Portland cement, and thus enable to reduce the cost of produced cement-based composites, and accordingly decrease harmful environmental impacts of cement production, especially CO2 emission. In this work, possible use of diatomite powder as partial Portland cement replacement in concrete compoistion was studied. The cement replacement ratio was 5 %, 10 %, 15 %, and 20 % by volume. Reference concrete mixture was prepared as well. The water/binder ratio was 0.5, and was kept similar for all prepared composite mixtures. For 28 days water cured samples, bulk density, specific density, strength parameters, and thermo-physical properties were tested. Results of experimental analysis showed high pozzolanic activity of diatomite resulting in reduced porosity and increased mechanical resistance of the developed concretes. The highly porous structure of diatomite particles helped to decrease concrete heat transport properties, despite of low total open porosity of the tested specimens.

Modification of the structure and Properties of Fine-Grained Concrete with Carbon Black Dispersion

The study shows that adding carbon black (soot) in the form of an aqueous dispersion into the composition of fine-grained concrete leads to an increase in bending and compressive strength of the samples: at a soot concentration of 0.005% by weight of cement, respectively, to 37.63 and 15.99%, at a concentration of 0.02% up to 26.39 and 26.39% due to compaction of the structure of the cement matrix. An intensification of cement hydration processes has been noted, confirmed by the results of IR-spectral, differential-thermal analyses and studies of the cement matrix microstructure in the composition of fine-grained concrete. On the surface of new formations in the composition of modified soot dispersion, the formation of needle-like crystals has been observed. On their surfaces, structures of spherulites formed with sizes ranging from 100 to 200 nm, which are typical for calcium hydro-sulfonic aluminates of 3CaO·Al2O3·3CaSO4·32H2O type. The formation of spherulites is observed in the pores of the cement matrix, which contributes to additional compaction of the structure of fine-grained concrete.

To the Question of the Influence of the Intensity of Active Centers on the Surface of Mineral Fillers on the Properties of Fine-Grained Concrete

The paper presents the results of experimental research on the evaluation of the possibility of using the indicators of surface activity of dispersed minerals as a criterion for determining the most effective way of their application in cement concrete. The obtained results allow to recommend to use such fillers as: quartz sand, barchan sand, wastes of electro smelting production for filling of cement concretes by the method "filling of cement in concrete": gliege, basalt, wastes of copper smelting production, fly ash of thermal power stations, zeolitecontaining rocks for filling of cement concretes by the method "filling of cement in concrete".

Сomplex Industrial Wastes Based Admixture for Improved Properties of Fine-Grained Concrete

In the process of development of architectural views on modern construction, there is a gradual change of urban planning policies and construction in general. One of the modern trends in design focusing on sustainable, energy efficient and environmentally friendly architecture creates a demand for new materials and products that reflect modern achievements in the field of building materials science. A variety of spatial planning options for buildings and structures emphasizes the diversification of building materials. At the same time, concrete as a basic building material has a huge potential in improving and adapting to solutions of environmental problems of the modern world.

Effect of mechanochemical activation of binder on properties of fine-grained concrete

Effect of mechanochemical activation of binder on properties of fine-grained concrete