Cement Constituents Research Articles

Estimation of Conventional Pcc Strength And Durability with Partial Replacement of Cement using Aluminium Powder and Rice Husk Ash

Bond is generally noted to be most costly constituents of cement. The whole development industry is looking for an appropriate and viable the waste item that would extensively limit the utilization of concretes and at last lessens the development cost. Rice husk slag (RHA) which has the pozzolanic properties is a route forward. A relative report on impacts of solid properties when OPC of differing evaluations was mostly supplanted by RHA is examined in this paper. Rate supplanting of OPC with RHA was 0, 10, 20, 30 and 40% individually. The compressive quality, water ingestion, shrinkage and solidness of cement were for the most part considered. The examination recommends that up to 20% supplanting of OPC with RHA can possibly be utilized as halfway concrete substitution, having great compressive quality execution and durability. Percentage supplanting of OPC with Aluminum powder (Al) is 0.5% which is kept steady. We are utilizing M sand rather than typical sand to diminish the expense of development and builds quality and sturdiness concrete. The examination proposes the supplanting of concrete with RHA and Aluminum powder expands the compressive quality, solidness, and diminishes the expense of development.

High-volume marble substitution in cement-paste: Towards a better sustainability

Substantial amounts of marble dust are available as construction wastes. This laboratory investigation examined the incorporation of the high volume of marble slurry as a cement replacement in pastes to produce environmentally friendly and lightweight building materials for sustainable construction. Dry unit mass of the marble composites varied from 1000 kg/m3 to 1520 kg/m3, mass loss upon exposure to sulfate solution varied from 9.8% to 16.2%, and compressive strength varied from 2.95 MPa to 28.63 MPa. The results revealed that the replacement of up to 60% of the cement constituent by marble powder in paste mixtures was effective. The composites are suitable as building materials for various applications in the manufacturing of bricks, tiles, and controlled low strength applications. Additionally, the beneficial effect of using a high amount of marble wastes considering the environmental and economic aspects are also discussed.

Kajian Eksperimental Pengaruh Penggantian Sebagian Semen Dengan Limbah Las Karbit Pada Mortar

<em><span>The Development of residential facilities will affect the increase in needs of building materials.. Cement is one of the building materials whose raw materials come from nature. Availability of natural resources will affect the production of cement. Carbide welding waste is the remainder of the carbide reaction to water which produces acyetilene gas where 60% of the waste contains Calcium Oxide (CaO) which is the main constituent of cement. This study aims to analyze the effect of partial replacement of cement with carbide weld waste on mortar compressive strength. The study was conducted by making a mortar cube with dimensions of 5 cm x 5 cm x 5 cm with mixed proportions of 1PC: 3PS. Variation of partial replacement of cement with carbide welding waste used as much as 0%, 5%, 10%, 15%, and 20%. The results showed that the mortar compressive strength without carbide welding waste was used as the control variable, amounting to 329.33 kg/cm2. Mortar compressive strength with the proportion of partial replacement of cement with carbide welding waste 5%, 10%, 15%, and 20% respectively are 286.38 kg/cm2, 243.42 kg/cm2, 200.47 kg/cm2, and 157.51 kg/cm2. based on pengijuan results indicate that the mortar is included in type M at a proportion of a maximum of 15% with a compressive strength of 200.47 kg/cm2 according to the minimum requirements of 175 kg/cm<sup>2</sup>.</span></em>

Determination of Mechanical Properties of Mortar by Using Fine Crushed Glass (FCG) and Waste Rubber (WR)

Concrete contain more amount of cement which will release more CO2 and effects the environment, therefore to reduce the amount of cement in a concrete one should have approach towards replacement of cement with other waste and cost effective material such as glass. Since waste glass is not biodegradable and therefore alternative usage of it is required. Such can be used as coarse aggregate and substitute of cement constituents in concrete and mortar. Also disposal of waste glass into landfills is one of the major issues that have been come across. This study aims on reducing such problems by the usage of waste glass as one of the replacing material in cement mortar. The pozzolanic activity of glass powder and properties of glass powder blended cement were evaluated. Also the mechanical and chemical properties of such blended mortar has been evaluated. The cement is replaced 0%, 5%, 10%, 15% and 20% by glass powder content by weight of cement. The test results shows that on adding the optimum amount of waste glass the compressive strength of mortar has been increased. Also at 5% replacement of cement with waste glass powder gives the best proportion to increase compressive strength and reduce the cost of conventional mortar.

Mechanical and thermal properties of cockles shell cementing material

Mortar of ordinary Portland cement was blended with cockles shellpowder at different weight ratios to investigate the effect of powderadmixture on their strength and thermal conductivity. Results showedthat addition of cockles shell powder at 50% of mortar weightimproves hardness and compressive strength notably and reduces thethermal conductivity of the end product. Results suggest thepossibility to incorporate cockles shell powders as constituents incement mortars for construction and plastering applications.

Parameters of Mortars Made of Aluminium and Portland Cement

Alumina cement is included in special cements, which are used primarily for the production of refractory materials. It is significantly different in chemical terms from the Portland cement commonly used in construction. The consequence of this are the different properties of these two hydraulic binders. Portland cement consists mainly of CaO and SiO2. In turn, the main constituents of aluminium cement are Al2O3 and CaO, which form calcium aluminates. However, the main phase constituent of aluminium cement is CA calcium monohydrate. It consists of about 36 ÷ 42% Al2O3 containing also a significant amount of gelenite (C2AS). Strength of Ca2 after three days of hydration is comparable to the strength of pure hydrated CA. It is also worth mentioning such phases as C2S and C4AF. They often occur in Portland cement and in clay cement. The article discusses the results of laboratory tests on the impact of replacing Portland cement with Portland cement on the physical and mechanical properties of mortar. The rheological characteristics of mortars, i.e. the consistency and parameters of hardened mortars, among others compressive strength, capillary rise and absorbability. Replacing aluminium cement with Portland cement in an amount of 10% causes an increase in compressive strength. The increase in compressive strength depends on the amount of Portland cement applied to the mortar. Parameters such as absorbability and capillary rising are improving. Compressive strength was tested after 1, 7, 28 days on samples with dimensions 4 × 4 × 16 cm. Absorption and capillary rising were tested 28 days after being moulded.

Laboratory and field evaluation of cement grouted bituminous mixes

Cement Grouted Bituminous Mix (CGBM) is a composite material, in which air voids present in the bituminous mix are grouted with a cementitious material. The main aim of this study is to develop and evaluate CGBM in the laboratory and field. A conventional dense graded Bituminous Concrete (BC) mix is also considered for comparison. This paper presents the details of different investigations carried out for evaluation of CGBM mix for properties such as Indirect Tensile Strength (ITS), Resilient Modulus and Dynamic Modulus at different temperatures. Performance characteristics such as rutting, fracture energy, moisture resistance, oil spillage and durability were also evaluated for the mixes. A CGBM test section has been laid on site and is being monitored for its performance. Results show that CGBM has better ITS, Resilient Modulus, Dynamic Modulus, and Rutting performance than a conventional bituminous mix. It shows a slight reduction in durability and crack resistance due to the relative brittleness of the hardened cement constituent but within acceptable limits. The material is also more resistant to damage by moisture and diesel. CGBM mixes are less temperature susceptible compared to conventional bituminous mix. Dynamic Modulus and Phase Angle master curves for CGBM mixes have been developed in the study. Full depth grouting was observed in field core samples and Micro Computed Tomography (Micro-CT) tests were carried out to check the air voids connectivity and their content in the CGBM mix.

A STUDY ON USE OF RICE HUSK ASH IN CONCRETE

The rice husk is an agricultural waste which is obtained from milling process of paddy and approximately 22% of the weight of paddy is rice husk. The waste is used as fuel in producing stream in parboiling process. The 25 % the weight of husk is converted into ash which is known as rice husk ash (RHA) and is again a waste which is disposed. This ash consists of amorphous silica which can be used as pozzolana in making concrete and cement instead of disposing it without compromising on the properties of cement or concrete if replaced in specific proportion with other constituents of cement or concrete. In this study the ordinary Portland cement is replaced in different proportion with RHA to obtain concrete with comparable and satisfactory strength and properties to that of normal concrete. The proportions of replacement chosen are at 2.5% interval starting from 5 % to 15 % and the casted concrete were tested under compression at different ages and results obtained are compared with normal concrete of same grade and it is co ncluded that the results are comparable.

RADIOACTIVE CEMENT OF PMMA AND HAP-Sm-153, Ho-166, OR RE-188 FOR BONE METASTASIS TREATMENT.

ABSTRACTPolymethylmetacrylte (PMMA) is used in the fields of dentistry and biomedicine as a constituent of bone cements. Hydroxyapatite (HAp) is a bioceramic produced naturally in the bones. PMMA and HAp are fundamental constituents in the preparation of bone cements. Bisphosphonates have also been used as radiopharmaceutical in dental implants and nuclear medicine, or as palliative systemic treatment for pain reduction in bone metastasis. Vertebroplasty and kyphoplasty are bone cement-based techniques used in orthopedics, being minimally invasive procedures with low risks of infections, applied in osteoporosis and high-impact fractures. Recently, Núcleo de Radiações Ionizantes da Universidade Federal de Minas Gerais proposed a synthetic composite of M-HAp with a metallic nuclide M. After irradiation, M-HAp was added to PMMA, compounding a radioactive bone cement that can recover bone body stabilization, pasting microfractures and recomposing the anatomy and functionality of the affected parts by the compression of bone metastases, with possible pain reduction through quick radiation-induced decompression. Computational dosimetric models, and the synthesis and characterization of bioceramics that incorporate Re-188, Ho-166, or Sm-153 have demonstrated the benefits of these biometrics as promising alternative therapies, mainly from their ability to maintain the ionization in the bone structure, thereby sparing the spinal cord. This article presents a review on this topic. Level of Evidence V, Expert Opinion.

Coal bottom ash natural radioactivity in building materials

The viability of ground coal bottom ash as a potential Portland cement constituent to be used in building materials is assessed. Currently, coal fly ash is used to produce Portland cements and concretes. However, coal bottom ash is mainly landfilled. Gamma spectrometry analysis, compressive strength, physical and chemical testing were performed. The ground coal bottom ash activity concentration index (I = 1.03) was compared to that of the coal fly ash (I = 1.11) provided from the same thermo-electrical power plant. Ground coal bottom ash could be used in building materials in the same way as coal fly ash as a Portland cement constituent.

Influence of pre-treated alum sludge on properties of high-strength self-compacting concrete

Abstract: The disposal of alum sludge (AS) produced from drinking water treatment plants is gradually becoming a threat to the environment. The conventional disposal by landfill is not feasible because AS is considered as hazardous waste. By contrast, treated alum sludge (TAS) contains useful chemical compounds (silicon dioxide and aluminium trioxide which are the main constituents of cement). This study explored the influence of TAS on the production of high-strength self-compacting concrete (HSSCC) made up of 5%, 10%, 15%, 20% and 25% cement replacement. The experimental work was divided into 15 mixes as well as three control mixes with three different water/powder (w/p) ratios (0.36, 0.38 and 0.4). The fresh properties of self-compacting concrete (SCC) were determined via the slump flow, V-funnel, V-funnel at T5 min and L-box tests to meet the flowability requirements. The strength and durability properties of SCC were also tested at different specimen ages. In addition, the effects of elevated temperature on TAS-incorporated concrete were observed at different temperatures for 3 h. Experimental results revealed the encouraging effects of TAS on the fresh, hardened and durability properties of HSSCC with maximum 15% of the cement component partially replaced with TAS. Meanwhile, losses of mass and strength were observed to be higher in the TAS-incorporated SCC than in the control concrete.

Suitability of natural calcined clays as supplementary cementitious material

The use of natural calcined clays as supplementary cementitious material (SCM) is becoming increasingly interesting for the cement industry. Most of investigations on calcined clays in literature work on pure kaolinitic and illitic clays. The presented research deals with 15 clays of different levels of quality, representing a wide range of natural clay deposits, were examined in terms of their suitability as a cement constituent. Therefore the clays were calcined under different burning conditions and different analyses to determine the reactivity of the calcined products were carried out and discussed. Furthermore, a sensitive method for determination of reactive silica which correlates clearly with clay's strength contribution was used. Cements with 20 and 40 mass % of calcined clay respectively were produced and examined in terms of their cement-relevant properties.The production of calcined clays in compliance with the requirements of EN 197-1 was possible with all examined varieties of clay. In addition, it was also possible to produce cements in strength class 42,5 R with the calcined clays. Clay mineralogy and burning conditions had a considerable influence on the calcined clays' contribution to strength within the cement. The overall results let expect the suitability of a broad range of calcined natural clays as SCM. The results of this study suggest that a broad range of natural calcined clays are suitable as SCM's.

Diagnostics and simulations of molecular formation in laser-induced plasmas

The formation of diatomic molecules or radicals in the cooling phase of laser-induced plasmas is mainly determined by thermodynamic parameters as the local plasma temperature, pressure and particle density. Better understanding of the molecular formation can be used for deeper material analysis and research. We adapted the well-established method reactive force field (ReaxFF) to simulate the formation of molecular bonds in time-resolved LIBS experiments.Instead of standard quantum mechanical or continuous simulation methods, ReaxFF uses a hybrid form based on the calculation of the bond order. The main advantage is the short computational time of molecular bonds compared to standard approaches. This allows the simulation of molecular formation at fixed temperatures in thermodynamic equilibria as well as temperature ramp simulations to get temperature dependent molecular concentration profiles. Molecular simulations enable the explanation of observed molecular band emission in LIBS experiments, the investigation of molecular interferences with other elements in the sample, and the signal optimization of molecular LIBS experiments. Furthermore, we show that the presented method can be used for a rough molecular temperature estimation of the plasma.As an application, we simulated the temperature behavior of the formation of calcium oxide (CaO) and compared the results to the law of mass action. Calcium and oxygen are the main constituents in cement, whose analysis is of high economic importance as it is part of concrete infrastructure buildings. LIBS measurements of CaO at different gate delays reveal the dynamic behavior of atomic and molecular emission. Furthermore, multivariate methods can be used for a cement separation on the basis of the molecular emission of CaO at 600.4 nm.

Comparative Study of Hydration Kinetics of Cement and Tricalcium Silicate Using Terahertz Spectroscopy and Density Functional Theory Simulations

Cement hydration is a process involving simultaneous reactions of cement constituents, primarily tricalcium silicate (C3S) and dicalcium silicate (C2S), with the formation of key hydration products, calcium silicate hydrate (C–S–H) and calcium hydroxide (Ca(OH)2). Compared to the conventionally explored mid-infrared spectroscopy which is bond specific, terahertz (THz) spectroscopy is highly sensitive to crystalline arrangements and resonances in THz frequency range are primarily due to bulk vibrational modes. Hence, THz spectroscopy can be an effective complimentary tool to study the hydration process as C3S gets converted to different polymorphs of C–S–H. To understand the origin and variation of THz resonances of C3S, C–S–H polymorphs and Ca(OH)2, vibrational modes of C3S, tobemorite 9, tobermorite 14, jennite, and portlandite have been calculated using density functional theory simulations. The origin of the main resonances has been studied using vibrational density of states. Simulations show, for C3S, the resonance around 520 cm−1 appears due to combined effect of symmetric and asymmetric vibrations in SiO4 tetrahedra, the resonance around 450 cm−1 appears due to the combined effect of symmetric and asymmetric SiO4 tetrahedra, and CaO vibrations and the resonance around 318 cm−1 is primarily due to CaO vibrations. THz spectroscopy has been performed to track and understand the contribution of C3S in cement hydration. By combining the simulation and experiments, this work clearly explains the reduction of 520 cm−1 resonance, the constant intensity of 450 cm−1 resonance and frequency shift of the main resonances as C3S is transformed into various polymorphs of C–S–H during hydration.

Comparison of mechanical properties of C-S-H and portlandite between nano-indentation experiments and a modeling approach using various simulation techniques

Abstract This work focuses on elastic modulus of two main constituents of cement based materials: portlandite (CH) and Calcium Silicates Hydrates (C-S-H). At nano-scale, the single CH crystal using Density Functional Theory (DFT) is investigated and the homogenized elastic modulus is obtained to be assessed as the RVE unit, which is used in nano-indentation simulation. Then the monolithic C-S-H structure with the chemical formula: (CaO)1.67(SiO2)(H2O)1.75 is simulated during the stretch process at strain rate 10−3 ps−1 by Molecular Dynamics (MD) method using ClayFF field, and its averaged elastic modulus is used to assess Young's moduli of LD and HD C-S-H phases considering the porosity factor. Then at micro scale, FEM is used to simulate the nano-indentation test on ABAQUS software and Young moduli of CH and C-S-H phases are determined by the load-depth curve. Young modulus by the load-depth curve simulated is calculated to compare with the experimental one. The results show that: 1) the Young's modulus calculated by DFT and Reuss-Voigt-Hill (RVH) calculation is 45.46 GPa, which is in quite good agreement with experimental averaged value (39.88 GPa) and with the literature values (45.94 GPa by Laugesen, 52.4 GPa by Speziale et al., 44.69 GPa by Kerisit et al., 46.58 GPa by Holuj et al.). 2) Based on the elastic modulus of the monolithic C-S-H structure by MD simulations, the assessment results on LD C-S-H and HD C-S-H after homogenization are very close to nanoindentation experiments data. 3) By FEM method, the simulated P-h curve is adopted to compare the extent of deviation from the experimental values, which is within an acceptable relative error. The homogenized elastic properties of polycrystals can be obtained by elastic constants of single crystal (using DFT and RVH estimation), thus can be used to explain the relationship between structure and mechanical properties of CH from nano-scale to micro-scale. Results enable to provide useful parameters for composite cements systems modeling and a method to calculate elastic modulus of other similar structures.

ASSESSMENT OF A NEW PORTLAND CEMENT COMPONENT: GROUND COAL BOTTOM ASH

Coal bottom ash is produced in electrical power stations as result of the coal combustion. Because coal fly ash and coal bottom ash are formed together in the same boiler, similar chemical and mineralogical composition is expected. The size and shape of these ashes is very different, and then, its effect on the performance must be studied. In order to get a similar grain size to that of the coal fly ash, the coal bottom ash was ground. Cement-based products are the main construction materials which manufacture requires the use of significant natural raw materials and energy. These manufacturing processes result in several types of emissions. In particular, the cement industry is under pressure to reduce CO2 emissions and some studies have shown different measures to reach CO2 reduction. For instance, reducing the clinker/cement factor will lead to a clear CO2 emission reduction. In this work, ground coal bottom ash is investigated to know its viability of being used as a new Portland cement constituent. Then, it is studied from a mechanical and durability point of view to evaluate the potential use of the coal bottom ash as an innovative binder. Ground coal bottom ash and fly ash mortars were more carbonated and exhibited a lower compressive strength than the reference mortars, but similar to each other. Keywords: coal bottom ash, Portland cement, Compressive strength, Durability

Preparation of iron-modified portland cement adsorbent and the investigation of its decolorization performance

The ordinary portland cement was modified by ferric salt impregnation method. Through the technologies of x-ray diffraction, scanning electron microscope and energy dispersive spectroscopy, the physicochemical properties of modified cement were detected and analyzed. It was found that after the modification, the main constituents of raw cement, tricalcium silicate and dicalcium silicate had been depleted, and the new crystal mineral of antarcticite replaced them. The iron precipitates and cement hydration products calcium silicate hydrate gel mainly existed in the form of amorphous on modified cement. The results of BET specific surface determination showed that the modified cement particles had mesoporous distribution. The results of adsorption experiment revealed modified cement exhibited excellent adsorption performance on reactive brilliant blue KNR. The combination mechanism between modified cement and adsorbate was mainly electrostatic interaction. The adsorption process satisfied with the pseudo-second order kinetics model, and the adsorption reaction was a spontaneous endothermic process.

Experimental and mechanical performance of shotcrete made with nanomaterials and fiber reinforcement

Studying the application of nanomaterial in cement matrixes is a new subject which has attracted the attention of researchers. Development of engineered cementitious composite has produced a solution to numerous shotcrete application challenges. In this study, mechanical tests were conducted to evaluate the strength of the concrete modified by fibers and nanomaterials in terms of comparison with conventional concrete and shotcrete.It is included in the application of Nano-Al2O3 and Nano-SiO2, which are some of the cement constituent. With proper homogenization, Nano-Al2O3 acts as filler for improving the pozzolanic reaction in the concrete. Nano-SiO2 particles also prevent the diffusion of external destructive factors into the concrete, thus improving the durability and stability of concrete. On the other hand, application of Alkali Resistant (AR) glass fibers improves the tensile and compressive strengths as well as concrete continuity and also resolves the changes created in mechanical properties of the fibers caused by alkaline concrete environment. Test results revealed that the maximum increase in compression and flexural strengths of modified concrete were 20.6 and 52%, respectively of its optimum compounds for 0.7% glass fiber with 1% Nano-Al2O3 and 1.5% Nano-SiO2, while in the modified shotcrete, these values were increased by 22.9 and 75%, respectively. In addition, application of the mentioned materials led to decrease of penetration depth and water absorption of the modified concrete by 46.78 and 2.5%, respectively, in relation to the conventional concrete. Also, addition of fibers and nanomaterials in shotcrete reduced the effect of cracking due to shrinkage and the modified shotcrete material rebound.

Alkali activated cements mix design for concretes application in high corrosive conditions

This paper covers the results of development of corrosion resistant ash alkali-activated cements based on regulation of phase composition of the hydration products through changing the alkali content, content of calciumcontaining cement constituents resulting in the increase strength and density of the cement stone. The results of study suggested to conclude that the cement compositions with predominance in the hydration products of weakly soluble low basic hydrosilicates of calcium, hydrogarnets and minerals similar to natural hydroaluminates exhibited the highest corrosion resistance. The results of comparison suggested to draw a conclusion that the alkali-activated cements Types APC III-400 and ACC V-400, according to National Ukrainian Standard DSTU B V.2.7, had high corrosion resistance compared to that of OPC, thus allowing to recommend the developed cements for the concretes intended for use in aggressive environments, inclusive of sodium and magnesium sulphates and others. Coefficients of corrosion resistance of concretes are higher than 1 after even 42 months.

Characterisation of a high pH cement backfill for the geological disposal of nuclear waste: The Nirex Reference Vault Backfill

In a conceptual UK geological disposal facility for nuclear waste within a high-strength, crystalline geology, a cement-based backfill material, known as Nirex Reference Vault Backfill (NRVB), will be used to provide a chemical barrier to radionuclide release. The NRVB is required to have specific properties to fulfil the operational requirements of the geological disposal facility (GDF); these are dependent on the chemical and physical properties of the cement constituent materials and also on the water content. With the passage of time, the raw materials eventually used to synthesise the backfill may not be the same as those used to formulate it. As such, there is a requirement to understand how NRVB performance may be affected by a change in raw material supply. In this paper, we present a review of the current knowledge of NRVB and results from a detailed characterisation of this material, comparing the differences in performance of the final product when different raw materials are used. Results showed that minor differences in the particle size, surface area and chemical composition of the raw material had an effect on the workability, compressive strength, the rate of hydration and the porosity, which may influence some of the design functions of NRVB. This study outlines the requirement to fully characterise cement backfill raw materials prior to use in a geological disposal facility and supports ongoing assessment of long-term post-closure safety.