On structural properties of the matrix phase of high-strength cement composites

2019 ◽  
pp. 4-10
Keyword(s):  
Mechanical Behavior ◽  
Structural Strength ◽  
Mutual Influence ◽  
Active Material ◽  
Matrix Phase ◽  
Cement Matrix ◽  
Filler Concentration ◽  
Relative Deformation ◽  
Cement Composites ◽  
Longitudinal Strains

From the standpoint of structural mechanics of the destruction of materials, the most important element of the structure of cement composites is the cement matrix phase, which predetermines the quality of structural strength and the mechanical behavior of the composite as a whole. The disclosure of the functional relationship between the acting stresses and deformations is one of the main stages in the study of the mechanical behavior of any solids of structural purpose. A comparative comparison of the mechanical behavior of macrostructures of experimental samples of cement composites of different composition on three varieties of quartz sand under axial compression is shown experimentally. The assessment of diagrams on the ultimate longitudinal and transverse relative deformation, longitudinal and transverse relative deformation of short-term ductility (creep), transverse deformation coefficient and differential coefficient of volumetric deformation and its increments, plasticity measures, location level of parametric point, the initial elastic modulus and elastic characteristics, and the specific fracture energy on the total longitudinal strains and strains of short ductility is made. A comprehensive methodology for assessing the structural and mechanical parameters of the structural strength of cement composites, obtained together on each prototype, makes it possible to obtain more differentiated characteristics. They reflect the synergistic effects of the mutual influence of structural and destructive structure formation and hardening of cement disperse systems, due to the filler concentration and quality indicators of the dispersed phase of cement composites. This makes it possible to more fully study the mechanical behavior of the material under load that, in turn, makes it possible to move from simple determination of quality parameters to active material quality management.

scholarly journals Improvement of Flexural and Compressive Strength of Cement Mortar by Graphene Nanoplatelets

2021 ◽  
Vol 15 (1) ◽  
pp. 165-171
Author(s):  
Yu Chen ◽  
Xingchen Li ◽  
Chuangchuang Li ◽  
Nana Zhang ◽  
Ronggui Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cement Hydration ◽  
Cement Mortar ◽  
Structural Strength ◽  
Graphene Nanoplatelets ◽  
Research Trend ◽  
Cement Matrix ◽  
Cement Composites ◽  
Engineering Structures

Background: In order to provide space for improving the durability of engineering structures by enhancing strength, the addition of nanomaterials has become a research trend in recent years. Graphene and its derivatives have unique properties and have been used in certain fields, which has also stimulated continuous and in-depth research on whether it can improve structural strength. Objective: This paper investigates the mechanical properties and mechanism of cement-based materials reinforced by Graphene Nanoplatelets (GNPs). Methods: Macroscopically, the flexural strength and compressive strengths of cement mortar were tested. Microscopically, the structure and composition were characterized and analyzed by SEM, EDS, and XRD. Results: The results show that the mechanical properties of modified cement mortar are directly related to the GNPs content. When the GNPs content is 0.04wt%, the flexural and compressive strength can still be increased by 12.8% and 33.9% after 28 d. Furthermore, the appropriate content of GNPs dispersed in the cement matrix played a role in promoting cement hydration. The interconnection with hydration products further reduces cracks and pores so that the cement composites form a denser microstructure. Conclusion: The results obtained above would provide references for understanding the reinforcement mechanism of GNPs.

Mechanical behavior of cement composites reinforced by aligned Enset fibers

2021 ◽  
Vol 304 ◽  
pp. 124607
Author(s):  
Markos Tsegaye Beyene ◽  
Michael El Kadi ◽  
Tamene Adugna Demissie ◽  
Danny Van Hemelrijck ◽  
Tine Tysmans
Keyword(s):  
Mechanical Behavior ◽  
Cement Composites

scholarly journals Preparation and Mechanical Properties of Graphene Oxide: Cement Nanocomposites

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Fakhim Babak ◽  
Hassani Abolfazl ◽  
Rashidi Alimorad ◽  
Ghodousi Parviz
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Graphene Oxide ◽  
Cement Mortar ◽  
Cement Matrix ◽  
Cement Composites ◽  
Xrd Diffraction ◽  
Calcium Silicate Hydrates ◽  
The Matrix ◽  
Scanning Electron

We investigate the performance of graphene oxide (GO) in improving mechanical properties of cement composites. A polycarboxylate superplasticizer was used to improve the dispersion of GO flakes in the cement. The mechanical strength of graphene-cement nanocomposites containing 0.1–2 wt% GO and 0.5 wt% superplasticizer was measured and compared with that of cement prepared without GO. We found that the tensile strength of the cement mortar increased with GO content, reaching 1.5%, a 48% increase in tensile strength. Ultra high-resolution field emission scanning electron microscopy (FE-SEM) used to observe the fracture surface of samples containing 1.5 wt% GO indicated that the nano-GO flakes were well dispersed in the matrix, and no aggregates were observed. FE-SEM observation also revealed good bonding between the GO surfaces and the surrounding cement matrix. In addition, XRD diffraction data showed growth of the calcium silicate hydrates (C-S-H) gels in GO cement mortar compared with the normal cement mortar.

scholarly journals Application of the nanoindentation method in assessing of properties of cement composites modified with silica-magnetite nanostructures

2018 ◽  
Vol 163 ◽  
pp. 02002 ◽  
Author(s):  
Elzbieta Horszczaruk ◽  
Roman Jedrzejewski ◽  
Jolanta Baranowska ◽  
Ewa Mijowska
Keyword(s):  
Mechanical Properties ◽  
Magnetite Nanoparticles ◽  
Positive Influence ◽  
Cement Matrix ◽  
Core Shell ◽  
Indentation Modulus ◽  
Cement Composites ◽  
Interfacial Zone ◽  
Berkovich Indenter ◽  
The Core

The results of investigation of the cement composites modified with 5% of silica-magnetite nanostructures of the core-shell type are presented in the paper. The nanoindentation method employing three-sided pyramidal Berkovich indenter was used in the research. The mechanical properties and microstructure of the modified cement composites were evaluated on the basis of the values of hardness and indentation modulus measured inside the cement matrix and in the aggregate-paste interfacial zone. The results were compared with those obtained for the reference composites without nanostructures. The positive influence of the presence of silica-magnetite nanoparticles on the tested properties was found out.

scholarly journals Properties of cement composites based on limestone depending on their granulometric composition

Vestnik MGSU ◽  
2020 ◽  
pp. 999-1006
Author(s):  
Svetlana V. Samchenko ◽  
Olga V. Alexandrova ◽  
Anton Yu. Gurkin
Keyword(s):  
Composite Materials ◽  
Portland Cement ◽  
Granulometric Composition ◽  
Coarse Grained ◽  
Cement Matrix ◽  
Cement Composites ◽  
Construction Costs ◽  
Initial Strength ◽  
Fine Grained ◽  
Additional Formation

Introduction. The use of limestone in cement compositions as an additional cementing agent solves both environmental and economic problems, namely, reduction of construction costs. In this regard, the study of the properties of the granulometric composition and volumetric content of cement composites, containing limestone, becomes increasingly important. The mission of this research is to optimize the properties of composite materials containing Portland cement and limestone by changing the granulometric composition of flour limestone. Materials and methods. Limestone, having three different Blaine milling fineness values of 250, 300 and 450 m2/kg, was used; its content reached 10, 15, 25 and 35 %. Cement and sand mortars were applied for testing purposes. The influence of the granulometric composition of limestone on the workability and compressive strength of composite cement was determined. Results. The effect of limestone on the limit shear stress becomes more pronounced when the amount of limestone increases to 25 and 35 %. This is most noticeable for limestone with a high content of fine fractions of 5–20 µm. The use of finely milled limestone increases the initial strength of the composite material. By adding 10 and 15 % of such limestone we can increase the strength by 16–20 %, and supplementary 25–35 % of limestone increases strength by 5–8 %. Strength enhancement is due to the reactivity of limestone and formation of calcium hydrocarbon aluminate 3CaO∙Al2O3∙СаСО3∙12H2O, which promotes formation of the crystal framework of the cement matrix. Additional formation of crystalline hydrates in the initial coagulation structure deteriorates the mortar workability, but increases its strength. Conclusions. The use of coarse-grained limestone significantly improves mortar workability, while the use of fine-grained limestone increases its content without reducing its strength. The granulometric composition of ground limestone shall be as close as possible to the granulometric composition of cement for the properties of composite materials containing Portland cement and limestone to be optimized.

scholarly journals Nanocelluloses: Natural-Based Materials for Fiber-Reinforced Cement Composites. A Critical Review

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 518 ◽  
Author(s):  
Ana Balea ◽  
Elena Fuente ◽  
Angeles Blanco ◽  
Carlos Negro
Keyword(s):  
Raw Material ◽  
Modulus Of Rupture ◽  
Cement Matrix ◽  
Future Research ◽  
Cementitious Composites ◽  
Natural Material ◽  
Cement Composites ◽  
Fiber Reinforced ◽  
Industrial Sectors ◽  
Reinforced Cement

Nanocelluloses (NCs) are bio-based nano-structurated products that open up new solutions for natural material sciences. Although a high number of papers have described their production, properties, and potential applications in multiple industrial sectors, no review to date has focused on their possible use in cementitious composites, which is the aim of this review. It describes how they could be applied in the manufacturing process as a raw material or an additive. NCs improve mechanical properties (internal bonding strength, modulus of elasticity (MOE), and modulus of rupture (MOR)), alter the rheology of the cement paste, and affect the physical properties of cements/cementitious composites. Additionally, the interactions between NCs and the other components of the fiber cement matrix are analyzed. The final result depends on many factors, such as the NC type, the dosage addition mode, the dispersion, the matrix type, and the curing process. However, all of these factors have not been studied in full so far. This review has also identified a number of unexplored areas of great potential for future research in relation to NC applications for fiber-reinforced cement composites, which will include their use as a surface treatment agent, an anionic flocculant, or an additive for wastewater treatment. Although NCs remain expensive, the market perspective is very promising.

Pitch-based carbon fiber reinforced cements: structure, performance, applications, and research needs

1992 ◽  
Vol 19 (1) ◽  
pp. 26-38 ◽  
Author(s):  
Nemkumar Banthia
Keyword(s):  
Carbon Fiber ◽  
Physical Properties ◽  
Mechanical Behavior ◽  
Key Words ◽  
Carbon Fibers ◽  
Fiber Reinforcement ◽  
Performance Characteristics ◽  
Future Research ◽  
Cement Composites ◽  
Research Needs

The improvements in the performance characteristics of cements due to carbon fiber reinforcement are described. In particular, the structure, the physical properties, the mechanical behavior, and the durability aspects of carbon–cement composites using pitch-based fibers are discussed. The various possible applications of these composites in structural and nonstructural applications are enumerated. The future research needs are identified. Key words: cements, carbon fibers, microstructure, strength, toughness, durability, applications.

Microstructural Study of Cement Composites Produced by Hazardous Waste Stabilization/Solidification

2012 ◽  
Vol 587 ◽  
pp. 97-101
Author(s):  
Bozena Vacenovska ◽  
Rostislav Drochytka ◽  
Vit Cerný
Keyword(s):  
Fly Ash ◽  
Hazardous Waste ◽  
Cement Composite ◽  
Cement Matrix ◽  
Main Task ◽  
Cement Composites ◽  
Microstructural Study ◽  
Waste Stabilization ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis

This paper deals with the chosen hazardous waste solidification/stabilisation (S/S) under the catalogue code 190811 using cement matrix with addition of classic fly ash and fluid fly ash as secondary raw binders. The main task of the research works was a microstructural study of the most successful S/S formula that will be used for development of new reclamation material. The S/S process product was subject to X-Ray analysis and to the electron microscopy analysis two years after its production to evaluate the possibility of degradation of the cement composite and releasing the contaminants into environment.

scholarly journals Meso-Scale Formulation of a Cracked-Hinge Model for Hybrid Fiber-Reinforced Cement Composites

Fibers ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 56
Author(s):  
Enzo Martinelli ◽  
Marco Pepe ◽  
Fernando Fraternali
Keyword(s):  
Crack Opening ◽  
Computational Cost ◽  
Cement Matrix ◽  
Homogeneous Material ◽  
Cement Composites ◽  
Fiber Reinforced ◽  
Reinforcing Fibers ◽  
Reinforced Cement ◽  
Displacement Based ◽  
Hinge Model

This study presents a non-linear cracked-hinge model for the post-cracking response of fiber-reinforced cementitious composites loaded in bending. The proposed displacement-based model follows a meso-mechanical approach, which makes it possible to consider explicitly the random distribution and orientation of the reinforcing fibers. Moreover, the model allows for considering two different fiber typologies whereas the cement matrix is modelled as a homogeneous material. The proposed mechanical model combines a fracture-based, stress-crack opening relationship for the cementitious matrix with generalized laws aimed to capture the crack-bridging effect played by the reinforcing fibers. These laws are derived by considering both the fiber-to-matrix bond mechanism and fiber anchoring action possibly due to hooked ends. The paper includes a numerical implementation of the proposed theory, which is validated against experimental results dealing with fiber-reinforced cement composites reinforced with different short fibers. The excellent theory vs. experiment matching demonstrates the high technical potential of the presented model, obtained at a reasonable computational cost.

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