scholarly journals Multi-Technique Characterization of a Fine Fraction of CDW and Assessment of Reactivity in a CDW/Lime System

Minerals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 590 ◽  
Author(s):  
Moisés Frías ◽  
Raquel Vigil de la Villa ◽  
Sagrario Martínez-Ramírez ◽  
Lucía Fernández-Carrasco ◽  
Ernesto Villar-Cociña ◽  
...  
Keyword(s):  
Fine Fraction ◽  
Mineralogical Composition ◽  
Industrial Applications ◽  
Pozzolanic Reaction ◽  
Cement Industry ◽  
Supplementary Cementitious Material ◽  
Construction And Demolition Wastes ◽  
Hydration Phases ◽  
Mineralogical Phases

This study analysed the fine particle (<5 mm) waste generated during siliceous or calcareous (depending on the composition of the original aggregate) concrete waste crushing. In the absence of industrial applications, such waste is amassed in open-air stockpiles on construction and demolition wastes (CDW) management plant grounds. The aim pursued was to find an outlet for that material in the cement industry. The starting waste, sourced from six Spanish management facilities, was characterised for its chemical and mineralogical composition, physical properties and pozzolanicity. The mineralogical phases in the CDW/lime system and their variations during the pozzolanic reaction were likewise identified. The findings showed that the fine waste consisted primarily in quartz, calcite, micas and feldspars, with smaller fractions of kaolinite and cement anhydrous phases. No portland cement hydration phases were identified. All six types analysed exhibited medium to low pozzolanicity, with the highest values recorded for the siliceous waste. Ettringite, C–S–H gels and calcium aluminate hydrates (C4AH13, C4AcH12) were identified during the pozzolanic reaction in CDW/lime system. Therefore, this type of waste can be reused as supplementary cementitious material with low-medium pozzolanic activity.

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.

Synthesis, Characterization, and Dynamic Behavior of Well-defined Dithiomaleimide-functionalized Maltodextrins

2020 ◽  
Vol 17 (2) ◽  
pp. 85-89
Author(s):  
Francisco J. Hidalgo ◽  
Nathan A.P. Lorentz ◽  
TinTin B. Luu ◽  
Jonathan D. Tran ◽  
Praveen D. Wickremasinghe ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Dynamic Behavior ◽  
Industrial Applications ◽  
19F Nmr ◽  
Nmr Studies ◽  
Synthetic Pathway ◽  
End Groups ◽  
Sugar End

: Maltodextrins have an increasing number of biomedical and industrial applications due to their attractive physicochemical properties such as biodegradability and biocompatibility. Herein, we describe the development of a synthetic pathway and characterization of thiol-responsive maltodextrin conjugates with dithiomaleimide linkages. 19F NMR studies were also conducted to demonstrate the exchange dynamics of the dithiomaleimide-functionalized sugar end groups.

Seed and juice characterization of pomegranate fruits grown in Tunisia: Comparison between sour and sweet cultivars revealed interesting properties for prospective industrial applications

2011 ◽  
Vol 33 (2) ◽  
pp. 374-381 ◽  
Author(s):  
Nejib Hasnaoui ◽  
Messaoud Mars ◽  
Sana Ghaffari ◽  
Mokhtar Trifi ◽  
Pablo Melgarejo ◽  
...  
Keyword(s):  
Industrial Applications

Application of the Continuous Rheoconversion Process (CRP) to Low Temperature HPDC-Part I: Microstructure

2006 ◽  
Vol 116-117 ◽  
pp. 402-405 ◽  
Author(s):  
Qin Yue Pan ◽  
Stuart Wiesner ◽  
Diran Apelian
Keyword(s):  
Low Temperature ◽  
Scale Up ◽  
Microstructural Characterization ◽  
Industrial Applications ◽  
Primary Phase ◽  
Heat Extraction ◽  
Initial Stage ◽  
Fraction Solid ◽  
Die Castings

The continuous rheoconversion process (CRP) is a novel slurry-on-demand process that was developed at MPI/WPI in 2002. The process is based on a passive liquid mixing technique in which the nucleation and growth of the primary phase are controlled using a specially designed “reactor”. The reactor provides heat extraction, copious nucleation, and forced convection during the initial stage of solidification, thus leading to the formation of globular structures. This paper presents our recent work on the scale-up of the CRP for industrial applications. Specifically, we demonstrate an important application of the CRP to low temperature (low fraction solid) HPDC. In Part I of this paper, we present salient results on microstructural characterization of CRP processed castings vs. conventional die castings.

Bentonite Clays Characterization in the Town of Sossego – Paraiba State

2015 ◽  
Vol 820 ◽  
pp. 65-70
Author(s):  
I.D.S. Pereira ◽  
V.N.F. Lisboa ◽  
I.A. Silva ◽  
J.M.R. Figueirêdo ◽  
G.A. Neves ◽  
...  
Keyword(s):  
Industrial Applications ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Drilling Fluids ◽  
X Ray Diffraction ◽  
Mineralogical Characterization ◽  
Bentonite Clays ◽  
The Town ◽  
Petroleum Drilling

Bentonite exhibt a range of industrial applications moving millions of dollars on the market per year. Among several applications if highlights it is use for petroleum drilling fluids. Thus, this work aims to characterize physical, mineralogical and technologically, the bentonitics clays of Sossego County, Paraíba, Brazil. Mineralogical characterization of clays was done through the following techniques: particle size analysis by laser diffraction, thermogravimetric and differential thermal analysis, chemical analysis and x-ray diffraction. The clays were turned in by treatment with sodium in Na2CO3 and then determined whether the apparent viscosity, plastic and volume of filtrate of clay-water dispersions. The results showed that the samples are of polycationic, showing levels of MgO, CaO and K2O, similar to those from Boa Vista County, Paraíba, Brazil, and consist of clay mineral kaolinite, quartz and esmec. The clays showed rheological properties that indicate potential for use in drilling fluids.

Use of Algerian Natural Mineral Deposit as Supplementary Cementitious Materials

2018 ◽  
Vol 34 ◽  
pp. 48-58 ◽  
Author(s):  
Karima Arroudj ◽  
Saida Dorbani ◽  
Mohamed Nadjib Oudjit ◽  
Arezki Tagnit-Hamou
Keyword(s):  
Mechanical Strength ◽  
Calcium Hydroxide ◽  
Cement Paste ◽  
Cementitious Materials ◽  
Pozzolanic Reaction ◽  
Heat Of Hydration ◽  
Cement Industry ◽  
Supplementary Cementitious Materials ◽  
Natural Mineral ◽  
Different Ages

Much of the current research on concrete engineering has been focused on including siliceous additions as supplementary cementitious materials (SCMs). Silica reacts with Calcium hydroxide release during cement hydration, and produces more C-S-H. The latter contributes to increase compactness, mechanical strengths and sustainability of concrete. This paper explores the hydration characteristics of cement paste based on various natural mineral additions, that are very abundant in Algeria and present a high silica content (ground natural pozzolana “PZ” and ground dune sand “DS”). For this purpose, several analyses were carried out on modified cement pastes and mortars. TheseSCMswere introduced by replacement levels of 15, 20 and 25 by weight of cement. We first, studied the effect of these SCMs on the heat of hydration and mechanical strength of mortars at different ages. The evolution of hydration of modified paste was studied, by using Thermal analysis (TG/TDA) at different ages, to analyze the Calcium Hydroxide (CH) content of the modified pastes. It is shown that the CH content of the mixes including SCMs is lower than that of the plain cement paste, indicating that silica reacts with the cement paste through a pozzolanic reaction. Increased pozzolanic activity results in higher amounts of Calcium Silicate Hydrate in the paste, which in turn results in higher compressive strength for modified cement mortars. Due to its crystalline morphology, the ground DS particles present a partial pozzolanic effect, compared to PZ which is semi-crystalline. Modified mortars by 20% DS can be the optimal composition. It presents satisfactory results: good mechanical strength and low heat of hydration. It can lead to an economic and sustainable concrete. Ground DS is very abounded in Africa and free of any impurities and can be a good alternativeSCMsin cement industry.

Characterization of clays from the Foumban region (west Cameroon) and evaluation for refractory brick manufacture

Clay Minerals ◽  
2018 ◽  
Vol 53 (3) ◽  
pp. 447-457
Author(s):  
A. Pountouenchi ◽  
D. Njoya ◽  
A. Njoya ◽  
D. Rabibisao ◽  
J.R. Mache ◽  
...  
Keyword(s):  
Material Properties ◽  
Major Element ◽  
Raw Materials ◽  
Mineralogical Composition ◽  
Refractory Brick ◽  
Major Element Chemistry ◽  
End Products ◽  
Materials Used ◽  
Steel Mould

ABSTRACTThree clayey materials named MY3, KK and KG originating from the Foumban region (west Cameroon) were analysed to determine their granulometry, plasticity, major-element chemistry and mineralogy. Dilatometric and ceramic behaviour were also investigated. Clays were shaped by uniaxial pressing in a steel mould. Shaped samples were heated at 1300, 1400 and 1500°C. The end products were characterized in terms of their density, porosity and compressive strength. Raw materials differ in terms of their mineralogical composition, grain-size distribution, Al2O3 content and the nature and abundance of impurities inducing specific thermal behaviour during dilatometric analysis and sintering tests. The final material properties may be related to the main features of the raw materials used.

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