scholarly journals THE MECHANISMS OF INFLUENCE OF A FINELY GROUND FILLER ON THE FORMATION OF CEMENT BINDER STRUCTURE

2020 ◽  
Vol 0 (41) ◽  
pp. 181-186
Author(s):  
Grigory Krasnyansky ◽  
Vasyl Klapchenko ◽  
Irina Aznauryan ◽  
Irina Kuznetsova
Keyword(s):  
Cement Binder ◽  
Binder Structure

scholarly journals Incorporation of Natural Fibres in Rendering Mortars for the Durability of Walls

2021 ◽  
Vol 6 (6) ◽  
pp. 82
Author(s):  
Cinthia Maia Pederneiras ◽  
Rosário Veiga ◽  
Jorge de Brito
Keyword(s):  
Modulus Of Elasticity ◽  
Drying Shrinkage ◽  
High Water ◽  
Natural Fibre ◽  
Accelerated Ageing ◽  
Flax Fibres ◽  
Aesthetic Appearance ◽  
Cement Binder ◽  
Drying Rates ◽  
Adherence Strength

One of the main functions of renders, together with the overall aesthetic appearance of the building, is the protection of the walls against external aggressive actions, such as water, salts solutions, erosion, and mechanical impacts. However, some anomalies of renders may drastically hinder their protection ability. In fact, cracking, high water permeability, and loss of adherence to the substrate of renders limit their barrier effect and favour the exposure of the substrate to external actions. The incorporation of fibres in mortars is commonly pointed out to reduce their cracking susceptibility, due to the probable enhancement in tensile strength and ductility of the composite. The use of lime in substitution of the part of the cement binder is seen as a method to reduce the modulus of elasticity and therefore enhance the resistance to cracking due to drying shrinkage. Therefore, this study investigates the wall protection-related properties of natural fibre-reinforced renders with cement-lime as a binary binder at 1:1:6 volumetric ratio. With this purpose, wool, coir, and flax fibres are used at 20% by total mortar volume and the water behaviour, cracking susceptibility, and adherence to the substrate of the mortars are assessed. Specifically, the water absorption by capillarity, drying rates, permeability to water under pressure, adherence strength, and shrinkage are evaluated. In order to evaluate the renders’ durability and therefore the durability of the protection to the walls, an artificial accelerated ageing test is performed based on heating-freezing and humidification-freezing cycles. The results indicate that the fibres’ addition reduced the shrinkage and modulus of elasticity of the mortars, which suggests lower susceptibility to cracking. The addition of fibres in mortars seemed to slightly affect their water performance and only at early ages. From the results, it was concluded that the adherence strength is not affected by the fibres’ incorporation. The fibres seem also to reduce the impacts of the ageing cycles on the mortar and the improvements provided by the fibres’ addition to the mortars’ performance remained after ageing when compared to the mortars without fibres, thus being a potential alternative to increase their durability. These aspects are particularly important for buildings, since they can extend their service life and promote their sustainability.

scholarly journals Research on the Properties of Mineral–Cement Emulsion Mixtures Using Recycled Road Pavement Materials

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 563
Author(s):  
Łukasz Skotnicki ◽  
Jarosław Kuźniewski ◽  
Antoni Szydło
Keyword(s):  
Road Construction ◽  
Base Layer ◽  
Asphalt Emulsion ◽  
Reclaimed Asphalt ◽  
Pavement Materials ◽  
Road Pavement ◽  
Road Surfaces ◽  
Cement Binder ◽  
Pavement Structures ◽  
By Products

The reduction in natural resources and aspects of environmental protection necessitate alternative uses of waste materials in the area of construction. Recycling is also observed in road construction where mineral–cement emulsion (MCE) mixtures are applied. The MCE mix is a conglomerate that can be used to make the base layer in road pavement structures. MCE mixes contain reclaimed asphalt from old, degraded road surfaces, aggregate improving the gradation, asphalt emulsion, and cement as a binder. The use of these ingredients, especially cement, can cause shrinkage and cracks in road layers. The article presents selected issues related to the problem of cracking in MCE mixtures. The authors of the study focused on reducing the cracking phenomenon in MCE mixes by using an innovative cement binder with recycled materials. The innovative cement binder based on dusty by-products from cement plants also contributes to the optimization of the recycling process in road surfaces. The research was carried out in the field of stiffness, fatigue life, crack resistance, and shrinkage analysis of mineral–cement emulsion mixes. It was found that it was possible to reduce the stiffness and the cracking in MCE mixes. The use of innovative binders will positively affect the durability of road pavements.

scholarly journals Studies of Fracture Toughness in Concretes Containing Fly Ash and Silica Fume in the First 28 Days of Curing

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 319
Author(s):  
Grzegorz Ludwik Golewski ◽  
Damian Marek Gil
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Fly Ash ◽  
Critical Stress ◽  
Critical Stress Intensity Factor ◽  
Early Age ◽  
Strength Parameters ◽  
Cement Binder ◽  
Mineral Additives

This paper presents the results of the fracture toughness of concretes containing two mineral additives. During the tests, the method of loading the specimens according to Mode I fracture was used. The research included an evaluation of mechanical parameters of concrete containing noncondensed silica fume (SF) in an amount of 10% and siliceous fly ash (FA) in the following amounts: 0%, 10% and 20%. The experiments were carried out on mature specimens, i.e., after 28 days of curing and specimens at an early age, i.e., after 3 and 7 days of curing. In the course of experiments, the effect of adding SF to the value of the critical stress intensity factor—KIcS in FA concretes in different periods of curing were evaluated. In addition, the basic strength parameters of concrete composites, i.e., compressive strength—fcm and splitting tensile strength—fctm, were measured. A novelty in the presented research is the evaluation of the fracture toughness of concretes with two mineral additives, assessed at an early age. During the tests, the structures of all composites and the nature of macroscopic crack propagation were also assessed. A modern and useful digital image correlation (DIC) technique was used to assess macroscopic cracks. Based on the conducted research, it was found the application of SF to FA concretes contributes to a significant increase in the fracture toughness of these materials at an early age. Moreover, on the basis of the obtained test results, it was found that the values of the critical stress intensity factor of analyzed concretes were convergent qualitatively with their strength parameters. It also has been demonstrated that in the first 28 days of concrete curing, the preferred solution is to replace cement with SF in the amount of 10% or to use a cement binder substitution with a combination of additives in proportions 10% SF + 10% FA. On the other hand, the composition of mineral additives in proportions 10% SF + 20% FA has a negative effect on the fracture mechanics parameters of concretes at an early age. Based on the analysis of the results of microstructural tests and the evaluation of the propagation of macroscopic cracks, it was established that along with the substitution of the cement binder with the combination of mineral additives, the composition of the cement matrix in these composites changes, which implies a different, i.e., quasi-plastic, behavior in the process of damage and destruction of the material.

Influence of Granulometric Composition and Type of Fillers and Additives on the Strength and Biostability of Cement Composites Based on Dry Building Mixtures

2021 ◽  
Vol 1043 ◽  
pp. 163-175
Author(s):  
Ekaterina Suraeva ◽  
Tatyana Elchishcheva ◽  
Dmitry Svetlov ◽  
Vasiliy Smirnov ◽  
Victor Afonin ◽  
...  
Keyword(s):  
Quartz Sand ◽  
Fungal Growth ◽  
High Strength ◽  
Strength Properties ◽  
System Structure ◽  
Fungal Resistance ◽  
System Stability ◽  
Environment Effects ◽  
Cement Binder ◽  
Insoluble Compounds

The structure of filled cementitious composite materials is formed as a result of hardening with the formation of a crystalline framework. The filler is involved in the building material crystal system structure formation. Chemically active fillers promote intensive release of hydration products that bind into insoluble compounds and increase the system stability. When developing the formulations for dry building mixtures, it is effective to use several fillers with different properties that complement each other, and biocidal additives increasing the materials resistance to environment effects formed by mold fungi. To create modified dry building mixtures based on cement binder, materials such as filler made of quartz sand of various fractions, fillers chrysotile and clinoptilolite and biocidal additives of the Teflex series were used. The composition with sand grains of 0.16–0.315 mm in size showed high strength properties in bending and compression. The introduction of chrysotile in an amount of 3% by weight of cement and quartz sand with a particle size of 0.16–0.315 mm increases the compressive and flexural strength by 7 and 13%, respectively, compared with the control composition. Clinoptilolite, introduced in an amount of 20% of the cement mass instead of one of the quartz sand fractions, increases the compressive strength of the composites up to 5%. The introduction of the Teflex series additives in the amount of at least 1% by weight of the binder ensures the composites’ fungal resistance. The additive “Teflex disinfectant” in an amount of at least 3% of the cement mass gives the composites fungicidal properties, the zone of no fungal growth on the nutrient solution near the infected samples is 4 mm.

scholarly journals MICROSCOPIC FEATURES OF CEMENT PASTE MODIFIED BY FINE PERLITE

2016 ◽  
Vol 7 ◽  
pp. 12
Author(s):  
Vladimír Hrbek ◽  
Veronika Koudelková ◽  
Pavel Padevět ◽  
Petr Šašek
Keyword(s):  
Electron Microscopy ◽  
Construction Industry ◽  
Lightweight Aggregate ◽  
Cement Matrix ◽  
Instrumented Indentation ◽  
Cement Sample ◽  
Cement Material ◽  
Material Development ◽  
Microscopic Features ◽  
Cement Binder

The use of waste material and replacement of binder element in cementitious composites is in focus of material development. Perlite in the construction industry is usually used in form of lightweight aggregate enhancing the insulating performance of concrete. This paper focuses on integration of fine perlite into the cement matrix and possible replacement of the cement binder in the composition of the material. The macromechanical performance of the modified paste is tested on specimens with 5, 10, 15 and 20% fine perlite substitution and pure cement sample. To distinguish the effect of the perlite on the microstructural level, pure cement material and specimen containing 10% of fine perlite are investigated by the electron microscopy. Furthermore, the mechanical properties of individual phases are examined and compared on same samples by instrumented indentation. The presented results enabled estimation of fine perlite impact on the macro and microscopic performance of the material.

scholarly journals MICROSTRUCTURE RESEARCH OF THE UNIDIRECTIONAL ORGANOPLASTIC BASED ON RUSAR-NT ARAMID FIBERS AND EPOXY-POLYSULFONE BINDER

2020 ◽  
pp. 19-26
Author(s):  
E.N. Kablov ◽  
◽  
G.S. Kulagina ◽  
G.F. Zhelezina ◽  
S.L. Lonskii ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Composite Material ◽  
Polymer Matrix ◽  
Packing Density ◽  
Tensile Tests ◽  
Polymer Composite Material ◽  
Aramid Fibers ◽  
Before And After ◽  
Binder Structure

This paper studies a polymer composite material - a unidirectional organoplastic based on Rusar-NT aramid fiber and a melt epoxy-polysulfone binder. Organoplastic has the following mechanical properties: tensile strength 2060 MPa, Young's modulus 101 GPa. The microstructure of the fiber and the polymer matrix in the organoplastic samples was studied before and after tensile tests. The features of the formation of the binder structure depending on the packing density of the fibers in organoplastics have been determined. The nature of the destruction of fibers and polymer matrix caused by the uniaxial tension has been studied.

scholarly journals Properties of Liquid Chemical Grouting Material for Soil Grouting using Non-cement Binder

2016 ◽  
Vol 16 (1) ◽  
pp. 45-52
Author(s):  
Jae-Hyun Lee ◽  
Yong-Ro Kim ◽  
Gyu-Yong Kim ◽  
Seong-Jin Yoon ◽  
Kyoung-Ju Mun
Keyword(s):  
Chemical Grouting ◽  
Grouting Material ◽  
Cement Binder ◽  
Liquid Chemical

scholarly journals A STUDY OF FACTORS AFFECTING THE FLUIDITY OF CEMENT

2019 ◽  
pp. 8-16
Author(s):  
Л. Шахова ◽  
L. Shakhova ◽  
Е. Черноситова ◽  
E. Chernositova ◽  
Л. Щелокова ◽  
...  
Keyword(s):  
Labor Costs ◽  
Factors Affecting ◽  
Correlation And Regression Analysis ◽  
Cement Powder ◽  
Production Factors ◽  
Variable Factor ◽  
Cement Binder ◽  
Cement Grinding ◽  
Relationship Of ◽  
The Relationship

The fluidity of cement powder has a significant impact on the duration and labor costs in the process of transportation and shipment of cement. This determines the relevance of the task of finding mechanisms to control this parameter. During the production process, the fluidity of the cement powder is formed depending on the properties of the initial cement charge, the requirements for the thinness of the grinding to the finished product, the hardware design and the conditions of the process. In turn, the fluidity of cement affects the grinding process and the productivity of the mill. The rheological characteristics of the cement binder change over time depending on the physical properties of the material, environmental conditions and the equipment used for its storage. The reasons for the deterioration of the flow of cement powder is still not fully studied. The article is devoted to the study of the main factors affecting the fluidity of cement. The results of the statistical analysis of cement fluidity depending on the thinness of cement grinding (on the residue on the sieve №008 and the specific surface area by Blaine method) humidity, bulk weight and weight in the most compacted state. In addition, the relationship of production factors and cement fluidity is considered. Correlation and regression analysis shows that the fluidity is affected by a variable factor, which is not yet quantified.

scholarly journals Development of a Zero-Cement Binder Using Slag, Fly Ash, and Rice Husk Ash with Chemical Activator

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
M. R. Karim ◽  
M. F. M. Zain ◽  
M. Jamil ◽  
F. C. Lai
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Setting Time ◽  
Time Flow ◽  
Alumina Gel ◽  
Cement Binder ◽  
Increasing Demand ◽  
Chemical Activator

The increasing demand and consumption of cement have necessitated the use of slag, fly ash, rice husk ash (RHA), and so forth as a supplement of cement in concrete construction. The aim of the study is to develop a zero-cement binder (Z-Cem) using slag, fly ash, and RHA combined with chemical activator. NaOH, Ca(OH)2, and KOH were used in varying weights and molar concentrations. Z-Cem was tested for its consistency, setting time, flow, compressive strength, XRD, SEM, and FTIR. The consistency and setting time of the Z-Cem paste increase with increasing RHA content. The Z-Cem mortar requires more superplasticizer to maintain a constant flow of110±5% compared with OPC. The compressive strength of the Z-Cem mortar is significantly influenced by the amounts, types, and molar concentration of the activators. The Z-Cem mortar achieves a compressive strength of 42–44 MPa at 28 days with 5% NaOH or at 2.5 molar concentrations. The FTIR results reveal that molecules in the Z-Cem mortar have a silica-hydrate (Si-H) bond with sodium or other inorganic metals (i.e., sodium/calcium-silica-hydrate-alumina gel). Therefore, Z-Cem could be developed using the aforementioned materials with the chemical activator.

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