scholarly journals Synthesis and Characterization of a Hybrid Cement Based on Fly Ash, Metakaolin and Portland Cement Clinker

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1084 ◽  
Author(s):  
Adriagni C. Barboza-Chavez ◽  
Lauren Y. Gómez-Zamorano ◽  
Jorge L. Acevedo-Dávila
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Cementitious Materials ◽  
Cement Industry ◽  
Supplementary Cementitious Materials ◽  
Cement Clinker ◽  
Dense Matrix ◽  
X Ray ◽  
Reduction Of Co2

Hybrid cement has become one of the most viable options in the reduction of CO2 emissions to the environment that are generated by the cement industry. This could be explained by the reduction of the content of clinker in the final mixture and substitution of the remaining percentage with supplementary cementitious materials with the help of an alkaline activation. Following that, properties that are provided by an Ordinary Portland Cement and of a geopolymer are mixed in this type of hybrid material and could be achieved at room temperature. Thereafter, the main objective of this research was to synthesize hybrid cements reducing the clinker content of Portland Cement up to 20% and use metakaolin and fly ash as supplementary cementitious materials in different proportions. The mixtures were alkaline activated with a mixture of sodium silicate and sodium hydroxide, calculating the amounts according to the percentage of Na2O that is present in each of the activators. The samples were then characterized using Compressive strength, X-ray diffraction, Fourier Transform Infrared Spectroscopy, and Scanning Electron Microscopy with energy-dispersive X-ray spectroscopy. The results indicated that the hybrid cements have similar mechanical properties than an Ordinary Portland Cement, and they resulted in a dense matrix of hydration products similar to those that are generated by cements and geopolymers.

scholarly journals Influence of supplementary cementitious materials on hydration and microstructure development of concrete

2019 ◽  
Vol 1 (1) ◽  
pp. 43-44
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Cement Clinker ◽  
Hydration Kinetics ◽  
Supplementary Cementitious Material ◽  
Industrial Manufacturing ◽  
Portland Cement Clinker ◽  
By Products

Several supplementary cementitious materials (SCM) were blended with Portland cement clinker in order to produce more sustainable binders. The use of such materials, where no additional clinkering process is involved, leads to a significant reduction in CO2 emissions per ton of cementitious materials (grinding, mixing and transport of concrete and use very little energy compared to the clinkering process) and is a means to (re)utilize by-products of industrial manufacturing processes. Fly ash, for example, is the most commonly used supplementary cementitious material. The blending of Portland cement with fly ash results in the reduction of the total amount of portlandite in the hydrated mixture [1-4], somewhat less pronounced than for silica fume as: the reactivity of fly ash is very limited and as the CaO in the fly ash is an additional source of calcium [5]. Since fly ash particles are more spherical in shape than cement particles, workability and pumpability can be improved, by adding fly ash, also, fly ashes can cause low early strengthening. In this paper, the effects of Fly-ash as SCM’s on microstructure and hydration kinetics are studied.

scholarly journals Feasibility of Using Biomass Fly Ash in Cementitious Materials

Proceedings ◽  
2019 ◽  
Vol 34 (1) ◽  
pp. 12
Author(s):  
Jonathan Page ◽  
Laurent Libessart ◽  
Chafika Djelal ◽  
Maurice Gonon ◽  
Issam Laiymani
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Water Demand ◽  
Isothermal Calorimetry ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Wood Biomass ◽  
Fly Ashes ◽  
X Ray ◽  
Biomass Fly Ash

In recent years, numerous studies focused on the development of sustainable cement-based binders through the use of supplementary cementitious materials such slag, fly ash, metakaolin, silica fume, pozzolan, etc. The use of wood biomass for power generation is increasingly common which lead to an important amount of waste produced in the combustion process such as fly ash, which must be transported to landfills for deposition, or used as sludge in farming. Depending on their chemical and physical characteristics, wood biomass fly ashes could be reuse in blended cements as supplementary cementitious material. Different sources of biomass fly ashes have been selected to evaluate their potential for use as a cement replacement. Their chemical and mineralogical compositions, as well as their morphology were first evaluated via X-ray and laser diffraction (XRD), inductively coupled plasma (ICP) and scanning electron microscopy (SEM coupled with energy-dispersive X-ray spectroscopy (EDX). Fly ashes showed variable physicochemical characteristics but some present interesting compositions for the intended use. One fly ash present a high content of CaO and minors of SiO2 and Al2O3. The chemical composition does not allow to categorize this fly ash as a pozzolan material but it may have a latent hydraulic behaviour, which could be interesting as cement substitution. This fly ash has been incorporated into a cement paste by progressive replacement of Portland cement (from 0 to 70%). It has been observed that biomass fly ash has a higher water demand compared to Portland cement. This additional water demand was evaluated by the Vicat consistency test and by an evaporometry method. The setting time and kinetic hydration of the biomass fly ash pastes were also assessed with the standardized Vicat test and by isothermal calorimetry.

scholarly journals A Review of the Mechanical Properties and Durability of Ecological Concretes in a Cold Climate in Comparison to Standard Ordinary Portland Cement-Based Concrete

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3467
Author(s):  
Ankit Kothari ◽  
Karin Habermehl-Cwirzen ◽  
Hans Hedlund ◽  
Andrzej Cwirzen
Keyword(s):  
Carbon Dioxide ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Cementitious Materials ◽  
Cold Climate ◽  
Supplementary Cementitious Materials ◽  
Short Exposure ◽  
Chemical Admixtures ◽  
Composite Cements ◽  
Alkali Activated

Most of the currently used concretes are based on ordinary Portland cement (OPC) which results in a high carbon dioxide footprint and thus has a negative environmental impact. Replacing OPCs, partially or fully by ecological binders, i.e., supplementary cementitious materials (SCMs) or alternative binders, aims to decrease the carbon dioxide footprint. Both solutions introduced a number of technological problems, including their performance, when exposed to low, subfreezing temperatures during casting operations and the hardening stage. This review indicates that the present knowledge enables the production of OPC-based concretes at temperatures as low as −10 °C, without the need of any additional measures such as, e.g., heating. Conversely, composite cements containing SCMs or alkali-activated binders (AACs) showed mixed performances, ranging from inferior to superior in comparison with OPC. Most concretes based on composite cements require pre/post heat curing or only a short exposure to sub-zero temperatures. At the same time, certain alkali-activated systems performed very well even at −20 °C without the need for additional curing. Chemical admixtures developed for OPC do not always perform well in other binder systems. This review showed that there is only a limited knowledge on how chemical admixtures work in ecological concretes at low temperatures and how to accelerate the hydration rate of composite cements containing high amounts of SCMs or AACs, when these are cured at subfreezing temperatures.

Effective Utilization of Industrial and Agricultural Waste for Developing Sustainable Self-Compacting Concrete

2022 ◽  
Vol 1048 ◽  
pp. 376-386
Author(s):  
M.S. Riyana ◽  
Dhanya Sathyan ◽  
M.K. Haridharan
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Portland Cement ◽  
Rice Husk ◽  
Ordinary Portland Cement ◽  
Rice Husk Ash ◽  
Cement Content ◽  
Supplementary Cementitious Materials ◽  
Ternary Blend ◽  
Self Compacting Concrete

SCC (Self compacting concrete) can fill formwork and encloses reinforcing bars under gravity and maintains homogeneity without vibration. SCC shortens the period of construction, guarantees compaction in confined zones, moreover terminates noise due to vibration. The wide spread application of SCC is restricted because of the high cost for the production of SCC with high cement content and chemical admixtures. In order to make the production of SCC economical, and to reduce the high cement content the Ordinary Portland Cement in SCC can be blended with pozzolanic materials like rice husk ash and supplementary cementitious materials like fly ash. In this paper the fresh state properties and mechanical properties such as compressive strength, split tensile strength and flexural strength of SCC with ternary blends of rice husk ash (RHA) and fly ash (FA) were studied. For this purpose, different mixes were prepared by replacing Ordinary Portland Cement (OPC) with 5%, 10%, 15% and 20% of rice husk ash (RHA) and the percentage of addition of fly ash (FA) is fixed as 15% for all these mixes. It was observed that the specimen incorporating 10% of rice husk ash (RHA) and 15% of fly ash (FA) as ternary blend exhibits better mechanical properties such as: Compressive, split tensile and flexural strengths at 28 days of age as compared to traditional mix of SCC without RHA (Rice Husk Ash) and FA (Fly Ash). This research demonstrates that the ideal percentage for a mixture of rice husk ash (RHA) and fly ash as ternary blend is 10% and 15% respectively.

Quantification of supplementary cementitious content in blended Portland cement using an iterative Rietveld–PONKCS technique

2017 ◽  
Vol 50 (2) ◽  
pp. 498-507 ◽  
Author(s):  
Yuri P. Stetsko ◽  
Natallia Shanahan ◽  
Harvey Deford ◽  
A. Zayed
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Binary Systems ◽  
Accurate Determination ◽  
Ternary Systems ◽  
Cementitious Materials ◽  
Iterative Refinement ◽  
Supplementary Cementitious Materials ◽  
Amorphous Content ◽  
Wide Range

An iterative Rietveld–PONKCS (partial or no known crystal structure) technique has been developed for precise and accurate determination of the weight percentages of predominantly amorphous supplementary cementitious materials (SCMs) contained in Portland cement–SCM blends. This technique involves the iterative refinement of the SCM amorphous phase (SCMAP) content, with the separation of the refinement of the SCMAP shape parameters from background refinement. The technique also includes an internal and external standard refinement of both the calibration SCM and the cement–SCM blend. This approach enables the separation of the contributions of the SCMs and the cement to the amorphous content of the cement–SCM blend. The technique has been successfully applied to binary systems of cement–slag and cement–fly ash, and ternary blends of cement–fly ash–slag, over a wide range of cement replacement levels. In the ternary systems, the proposed technique was successfully able to separate the individual amorphous contributions of slag and fly ash to the total amorphous content of the system. The approach was also implemented on a pair of commercially available binary blended cements containing 30% slag and 30% fly ash, respectively.

scholarly journals Measurement of Pozzolanic Activity Index of Scoria, Pumice, and Rice Husk Ash as Potential Supplementary Cementitious Materials for Portland Cement

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Hieronimi A. Mboya ◽  
Cecil K. King’ondu ◽  
Karoli N. Njau ◽  
Alex L. Mrema
Keyword(s):  
Portland Cement ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Activity Index ◽  
Cementitious Materials ◽  
Pozzolanic Activity ◽  
Supplementary Cementitious Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Setting Times

This work investigated the properties of scoria and pumice as supplementary cementitious materials (SCMs) for Portland cement and compared to those of rice husk ash (RHA). X-ray fluorescence, X-ray diffraction, and pozzolanic activity index (PAI) tests confirmed the suitability of these two materials as potential SCMs. Scoria and RHA samples achieved over 75% PAI at 7 days whereas pumice did this after 28 days. Initial and final mean setting times observed for the composite cement blended with these materials were 166 and 285 min, respectively. These setting times are longer than that of ordinary Portland cement but shorter compared to that of common Portland pozzolana cement. The ultimate mean compressive strengths achieved at 28 days of curing were 42.5, 44.8, and 43.0 MPa for scoria, pumice, and RHA, respectively, signifying that these materials are good SCMs. Higher fineness yielded higher ultimate mean strength. For instance, a scoria sample with a fineness of 575 m2/kg achieved the strength of 52.2 MPa after 28 days.

scholarly journals Metal magnesium industry waste for partial replacement of Portland cement

2020 ◽  
Vol 13 (6) ◽  
Author(s):  
Maysa Lorena Figueiredo Martins ◽  
Richard Rodrigues Barreto ◽  
Paulo Roberto Ribeiro Soares Junior ◽  
Ivete Peixoto Pinheiro ◽  
Augusto Cesar da Silva Bezerra
Keyword(s):  
Portland Cement ◽  
Mineralogical Composition ◽  
High Energy ◽  
Cement Industry ◽  
Cement Clinker ◽  
Partial Replacement ◽  
Supplementary Cementitious Material ◽  
X Ray ◽  
Industry Waste ◽  
Energy Demands

ABSTRACT: The high demand for concrete has triggered studies on the mitigation of Portland cement production impacts, such as greenhouse gas emissions and energy demands, in addition to enabling cost reduction. Partial replacement of cement with other materials has been employed as an alternative to minimize the damage caused by the cement industry. In this regard, it is necessary to use materials that efficiently replace cement clinker. This study uses waste generated from the production of metallic magnesium as a partial replacement for Portland cement. The substitution is aimed at reducing the amount of clinker used, as its production necessitates high energy consumption and results in emission of large quantities of CO2 into the atmosphere. The tailings were characterized via X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and granulometric analysis. For evaluating the mechanical behavior and porosity, 25% of the cement (by mass) was replaced with tailings, and the resulting composite was molded into cylindrical specimens. After curing for 28 and 91 days, all specimens underwent compression testing. The results of the physical characterization showed that more than 65% of the tailing grain was lesser than 45 μm in size, which contributes to the packaging effect. In terms of the chemical and mineralogical composition, the tailing had high levels of calcium, and the predominant phases could be identified. The compressive strength of the mortar with substitution was higher than 40 MPa. The convergence observed between the results of the different characterization techniques demonstrates the efficiency of using the waste as a supplementary cementitious material.

scholarly journals Investigation of fly ash properties with purpose of its utilization as a secondary raw material for portland cement clinker production

2006 ◽  
Vol 60 (9-10) ◽  
pp. 245-252 ◽  
Author(s):  
Zvezdana Bascarevic ◽  
Miroslav Komljenovic ◽  
Ljiljana Petrasinovic-Stojkanovic ◽  
Natasa Jovanovic ◽  
Aleksandra Rosic ◽  
...  
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Power Plants ◽  
Building Materials ◽  
Thermal Power ◽  
Cement Industry ◽  
Raw Material ◽  
Cement Clinker ◽  
Physical Chemical ◽  
Portland Cement Clinker

In this paper the results of the investigated properties of fly ash from four thermal power plants in Serbia are presented. The physical, chemical, mineralogical and thermal characterization of fly ash was carried out, in order to determine the possibility to utilize this material in the building materials industry, foremost in the cement industry. It was determined that, although there are differences concerning the physical, chemical, and mineralogical characteristics of the investigated samples, they are very similar concerning their thermal characteristics. It was concluded that using fly ash as one of the raw components in the mixture for Portland cement clinker synthesis, not only enables the substitution of natural resources, but it might have a positive effect on the lowering of the sintering temperature.

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