scholarly journals Design and Evaluation of an Ultrahigh-Strength Coral Aggregate Concrete for Maritime and Reef Engineering

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5871
Author(s):  
Jinming Liu ◽  
Boyu Ju ◽  
Wei Xie ◽  
Huang Yu ◽  
Haiying Xiao ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Autogenous Shrinkage ◽  
X Ray Diffraction ◽  
Early Hydration ◽  
X Ray ◽  
Ultrahigh Strength ◽  
Marine Concrete ◽  
Marine Engineering ◽  
Reactive Powder ◽  
Economical Alternative

In this paper, an ultrahigh-strength marine concrete containing coral aggregates is developed. Concrete fabricated from marine sources is considered an effective and economical alternative for marine engineering and the construction of remote islands. To protect sea coral ecosystems, the coral aggregates used for construction are only efflorescent coral debris. To achieve the expected mechanical performance from the studied concrete, an optimal mixture design is conducted to determine the optimal proportions of components, in order to optimize the compressive strength. The mechanical properties and the autogenous shrinkage, as well as the heat flow of early hydration reactions, are measured. The hydration products fill up the pores of coral aggregates, endowing our concrete with flowability and self-compacting ability. The phases in the marine concrete are identified via X-ray diffraction analysis. The 28-day compressive and flexural strength of the developed marine concrete achieve 116.76 MPa and 18.24 MPa, respectively. On account of the lower cement content and the internal curing provided by coral aggregates, the volume change resulting from autogenous shrinkage is only 63.11% of that of ordinary reactive powder concrete.

scholarly journals Functional Bionanocomposite Fibers of Chitosan Filled with Cellulose Nanofibers Obtained by Gel Spinning

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1563
Author(s):  
Sofia Marquez-Bravo ◽  
Ingo Doench ◽  
Pamela Molina ◽  
Flor Estefany Bentley ◽  
Arnaud Kamdem Tamo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Cellulose Nanofibers ◽  
Microstructural Characterization ◽  
Fiber Formation ◽  
Fiber Direction ◽  
Composite Fibers ◽  
X Ray Diffraction ◽  
Gel Spinning ◽  
X Ray

Extremely high mechanical performance spun bionanocomposite fibers of chitosan (CHI), and cellulose nanofibers (CNFs) were successfully achieved by gel spinning of CHI aqueous viscous formulations filled with CNFs. The microstructural characterization of the fibers by X-ray diffraction revealed the crystallization of the CHI polymer chains into anhydrous chitosan allomorph. The spinning process combining acidic–basic–neutralization–stretching–drying steps allowed obtaining CHI/CNF composite fibers of high crystallinity, with enhanced effect at incorporating the CNFs. Chitosan crystallization seems to be promoted by the presence of cellulose nanofibers, serving as nucleation sites for the growing of CHI crystals. Moreover, the preferential orientation of both CNFs and CHI crystals along the spun fiber direction was revealed in the two-dimensional X-ray diffraction patterns. By increasing the CNF amount up to the optimum concentration of 0.4 wt % in the viscous CHI/CNF collodion, Young’s modulus of the spun fibers significantly increased up to 8 GPa. Similarly, the stress at break and the yield stress drastically increased from 115 to 163 MPa, and from 67 to 119 MPa, respectively, by adding only 0.4 wt % of CNFs into a collodion solution containing 4 wt % of chitosan. The toughness of the CHI-based fibers thereby increased from 5 to 9 MJ.m−3. For higher CNFs contents like 0.5 wt %, the high mechanical performance of the CHI/CNF composite fibers was still observed, but with a slight worsening of the mechanical parameters, which may be related to a minor disruption of the CHI matrix hydrogel network constituting the collodion and gel fiber, as precursor state for the dry fiber formation. Finally, the rheological behavior observed for the different CHI/CNF viscous collodions and the obtained structural, thermal and mechanical properties results revealed an optimum matrix/filler compatibility and interface when adding 0.4 wt % of nanofibrillated cellulose (CNF) into 4 wt % CHI formulations, yielding functional bionanocomposite fibers of outstanding mechanical properties.

D-4 Quantitative In-Situ X-ray Diffraction Analysis of Early Hydration of Portland Cement at Defined Temperatures

2008 ◽  
Vol 23 (2) ◽  
pp. 175-175 ◽  
Author(s):  
C. Hesse ◽  
F. Goetz-Neunhoeffer ◽  
J. Neubauer ◽  
M. Braeu ◽  
P. Gaeberlein ◽  
...  
Keyword(s):  
Portland Cement ◽  
Diffraction Analysis ◽  
X Ray Diffraction ◽  
Early Hydration ◽  
X Ray

Incorporation of AlCl3 and As2O3 in Composite Cement Systems

2003 ◽  
Vol 807 ◽  
Author(s):  
J Hill ◽  
J H Sharp
Keyword(s):  
Aluminium Chloride ◽  
X Ray Diffraction ◽  
Early Hydration ◽  
X Ray ◽  
Friedel’S Salt ◽  
Fuel Ash ◽  
Blastfurnace Slag ◽  
Addition Level ◽  
Cementitious Systems ◽  
Composite Cements

ABSTRACTAs part of an investigation into the consequences of adding inorganic metal salts to composite cements, based on blastfurnace slag (BFS) and pulverised fuel ash (PFA), the effect on the hydration behaviour of adding AlCl3 or As2O3 to the mix water of a number of cementitious systems was investigated using isothermal conduction calorimetry (ICC) and x-ray diffraction (XRD). Four cement systems were investigated; ordinary Portland cement (OPC), 3:1 BFS: OPC, 9:1 BFS:OPC and 3:1 PFA:OPC. AlCl3·7H2O and As2O3 were added to the mix water at 0.1% and 1% concentrations. Results from ICC indicated that the addition of As2O3 had very little effect on the setting and early hydration of any of the cements. AlCl3, however, inhibited the setting of the composite cements at the 1% addition level but accelerated the OPC at 0.1%. The expected hydration products were observed, with the additional observation of Friedel's salt in the presence of aluminium chloride additions and vaterite in both the aluminium and arsenic-containing systems after 180 days hydration.

scholarly journals Characterization of Slag Reprocessing Tailings-Based Geopolymers in Marine Environment

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 832 ◽  
Author(s):  
Jie Wu ◽  
Jing Li ◽  
Feng Rao ◽  
Wanzhong Yin
Keyword(s):  
Compressive Strength ◽  
Marine Environment ◽  
Copper Slag ◽  
X Ray Diffraction ◽  
Strength Measurement ◽  
X Ray ◽  
Sodium Aluminosilicate ◽  
Marine Concrete ◽  
Sodium Aluminosilicate Hydrate

In this study, copper slag reprocessing tailings (CSRT) were synthesized into geopolymers with 40%, 50% and 60% metakaolin. The evolution of compressive strength and microstructures of CSRT-based geopolymers in a marine environment was investigated. Except for compressive strength measurement, the characterizations of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM) were included. It was found that marine conditions changed the Si/Al ratio in the sodium-aluminosilicate-hydrate (N-A-S-H) gel backbone, promoted the geopolymerization process, led to more Q4(3Al), Q4(2Al) and Q4(1Al) gel formation and a higher compressive strength of the geopolymers. This provided a basis for the preparation of CSRT-based geopolymers into marine concrete.

Hydration Behavior of Metakaolin-Cement Pastes with Different Contents of Reactive Aluminous at Early Age

2010 ◽  
Vol 150-151 ◽  
pp. 419-424
Author(s):  
Tao Sun ◽  
Zhong He Shui ◽  
Gui Ming Wang
Keyword(s):  
Early Period ◽  
Xrd Analysis ◽  
Insoluble Residue ◽  
Early Age ◽  
X Ray Diffraction ◽  
Early Hydration ◽  
Cement Pastes ◽  
Reaction Velocity ◽  
X Ray ◽  
Reactive Silica

What kind of role do the reactive aluminous has played during early hydration process of metakaolin-cement paste is investigated in present study. Therefore, metakaolin(MK) samples containing 45.94%, 22.86%, 0% reactive aluminous are prepared, respectively. In addition, X-ray Diffraction (XRD) analysis is employed to identify the crystalline phases of all specimens. The amount of acid-insoluble residue (AIR) of all specimens is used to evaluate the unreacted materials. The results obtained indicate that reactive aluminous can promote development of the early period strength significantly. Reactive silica and reactive aluminous reaction velocity was very slow during the first three days, then increased. The reaction velocity of reactive aluminous was faster than reactive silica between the first day and third day, but it shows an opposite result between the third day and seventh day.

scholarly journals Use of basaltic waste as red ceramic raw material

Cerâmica ◽  
2016 ◽  
Vol 62 (362) ◽  
pp. 157-162 ◽  
Author(s):  
T. M. Mendes ◽  
G. Morales ◽  
P. J. Reis
Keyword(s):  
Size Distribution ◽  
Mechanical Performance ◽  
Raw Materials ◽  
Raw Material ◽  
Metropolitan Region ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructure Evaluation ◽  
Firing Shrinkage ◽  
Physical And Chemical

Abstract Nowadays, environmental codes restrict the emission of particulate matters, which result in these residues being collected by plant filters. This basaltic waste came from construction aggregate plants located in the Metropolitan Region of Londrina (State of Paraná, Brazil). Initially, the basaltic waste was submitted to sieving (< 75 μm) and the powder obtained was characterized in terms of density and particle size distribution. The plasticity of ceramic mass containing 0%, 10%, 20%, 30%, 40% and 50% of basaltic waste was measured by Atterberg method. The chemical composition of ceramic formulations containing 0% and 20% of basaltic waste was determined by X-ray fluorescence. The prismatic samples were molded by extrusion and fired at 850 °C. The specimens were also tested to determine density, water absorption, drying and firing shrinkages, flexural strength, and Young's modulus. Microstructure evaluation was conducted by scanning electron microscopy, X-ray diffraction, and mercury intrusion porosimetry. Basaltic powder has similar physical and chemical characteristics when compared to other raw materials, and contributes to ceramic processing by reducing drying and firing shrinkage. Mechanical performance of mixtures containing basaltic powder is equivalent to mixtures without waste. Microstructural aspects such as pore size distribution were modified by basaltic powder; albite phase related to basaltic powder was identified by X-ray diffraction.

Hydration of Synthetized Clinker Phases C3S and C3A with Metakaolin in Isothermal Conditions

2015 ◽  
Vol 1124 ◽  
pp. 23-30 ◽  
Author(s):  
Martin Boháč ◽  
Radoslav Novotný ◽  
Jiří Másilko ◽  
Tomáš Opravil ◽  
František Šoukal ◽  
...  
Keyword(s):  
Phase Composition ◽  
Heat Flow ◽  
Isothermal Calorimetry ◽  
X Ray Diffraction ◽  
Early Hydration ◽  
X Ray ◽  
Calorimetric Measurements ◽  
Flow Development ◽  
Cementitious Systems

Heat flow development during initial hydration of fresh pastes based on mixtures of pure clinker phases C3S and C3A with metakaolin was investigated by means of isothermal calorimetry. Phase composition development was examined by "in situ" X-ray diffraction technique. Obtained results from calorimetric measurements and X-ray diffraction were correlated with recent studies in field of hydration of cementitious systems. The effect of co-sintering of clinker phases on early hydration was characterized by isothermal calorimetry.

Crystallization and Mechanical Properties of Glass-Ceramic from Silicon Slag

2014 ◽  
Vol 953-954 ◽  
pp. 1643-1648
Author(s):  
Hang Li ◽  
Li Qiang Liu ◽  
Min Jing ◽  
Zhi Gang Wang ◽  
Zheng Wang ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Mechanical Performance ◽  
Glass Ceramics ◽  
Ceramic Materials ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Talcum Powder ◽  
X Ray ◽  
Glass Ceramic Materials ◽  
Spherical Grains

The glass-ceramic materials were produced from silicon slag with the addition of talcum powder and TiO2 by melting them in an electrically heated furnace and subsequent heat treatment at various temperatures and time. The microstructure and crystallization behaviors of glass–ceramics have been investigated by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). With the increase of silicon slag content, the sequent precipitate phase is: krinovite Na (Mg1.9Fe0.1)Cr (SiO)3O, pseudobrookite Fe2TiO5 and anorthite Ca (Al2Si2O8), enstatite ferroan MgFeSi2O6, and albite Na (AlSi3O8). The shape of crystals was spherical grains. The glass–ceramic sample obtained from 70% silicon slag had the excellent mechanical performance including flexural strength of 200.45 MPa and Vickers micro hardness of 909.72 MPa.

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