Geopolymer Materials Based on Natural Pozzolans from the Moroccan Middle Atlas

The pozzolans of the Moroccan Middle Atlas are derived from a low explosive volcanism, mostly strombolian. They are mainly composed of olivine and pyroxene, presenting a less homogeneous structure (irregular vesicles). The main target of this project is to study the use of natural pozzolans (NP) and metakaolin as precursors for the production of geopolymeric binders. The characterization of raw materials and elaborated geopolymers was carried out to study their mineralogical, chemical, microstructural, and mechanical properties. The studied pozzolans and kaolin were crushed, grinded, and sifted to get a fine grain size diameter of less than 100 µm. Then, they were calcined at 750 °C for 2 h to achieve an amorphous structure, increasing of their reactivity. Geopolymer production consists of mixing pozzolans and metakaolin with different amounts with an alkaline solution of sodium hydroxide and sodium silicates. The mass proportion of metakaolin (MK) used in this study was 10%, 20%, and 30%. In the present work, the amount of metakaolin was added as a source of alumina. The elaborated geopolymers were characterized using XRD, FTIR, TGA, and SEM analyses. The compressive strength was measured at 7, 14, and 28 days. The results showed interesting mechanical proprieties at about 18 MPa at 28 days with the mixture containing 20% MK. The addition of MK showed a significant increase in mechanical properties of the elaborated geopolymer. Meanwhile, the other results confirmed the training of new phases in addition to N-A-S-H gel. All these results indicate that the use of pozzolans in the production of geopolymers could be a great solution for the sustainable management of this mineral resource.

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In Situ Preparation and Mechanical Properties of (ZrB2+ZrC)/Zr3[Al(Si)]4C6 Composites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.602-603.438 ◽

2014 ◽

Vol 602-603 ◽

pp. 438-442

Author(s):

Lei Yu ◽

Jian Yang ◽

Tai Qiu

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Bending Strength ◽

Coefficient Of Thermal Expansion ◽

Raw Materials ◽

Linear Increase ◽

Fine Grain ◽

Fine Grain Strengthening ◽

Uniform Microstructure

Fully dense (ZrB2+ZrC)/Zr3[Al (Si)]4C6 composites with ZrB2 content varying from 0 to 15 vol.% and fixed ZrC content of 10 vol.% were successfully prepared by in situ hot-pressing in Ar atmosphere using ZrH2, Al, Si, C and B4C as raw materials. With the increase of ZrB2 content, both the bending strength and fracture toughness of the composites increase and then decrease. The synergistic action of ZrB2 and ZrC as reinforcements shows significant strengthening and toughing effect to the Zr3[Al (Si)]4C6 matrix. The composite with 10 vol.% ZrB2 shows the optimal mechanical properties: 516 MPa for bending strength and 6.52 MPa·m1/2 for fracture toughness. With the increase of ZrB2 content, the Vickers hardness of the composites shows a near-linear increase from 15.3 GPa to 16.7 GPa. The strengthening and toughening effect can be ascribed to the unique mechanical properties of ZrB2 and ZrC reinforcements, the differences in coefficient of thermal expansion and modulus between them and Zr3[Al (Si)]4C6 matrix, fine grain strengthening and uniform microstructure derived by the in situ synthesis reaction.

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Characterization of Medium Density Particleborads Using Agricultural Residues

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1088.656 ◽

2015 ◽

Vol 1088 ◽

pp. 656-659

Author(s):

Ivaldo D. Valarelli ◽

Rosane A.G. Battistelle ◽

Barbara Stolte Bezerra ◽

Luiz A. Melgaço N. Branco ◽

Eduardo Chahud ◽

...

Keyword(s):

Mechanical Properties ◽

Castor Oil ◽

Mechanical Characteristics ◽

Mechanical Characterization ◽

Raw Materials ◽

Construction Materials ◽

Agricultural Residues ◽

Medium Density ◽

Polyurethane Resin

In recent years the production of products derived from wood and bamboo are increasing, due to the search for a more rational exploitation of these raw materials. Amongst these products, the particleboards production combine sustainability and rationality in the use of these materials. In this context, this work has the objective to study the application of alternative raw materials in the manufacture of Medium Density Particleboards (MDP), using residues from industrial processimg of coffee and bamboo. MDP had been produced with particles of giganteus bamboo of the Dendrocalamus species and particle of coffee rind in the intermediate layer of the particleboard, bonded with polyurethane resin based on castor oil. The physical and mechanical characterization was carried out accordingly to NBR 14810-3 (2006). The physical properties evaluated were: of water absorption for 2h and 24h; thickness swallowing for 2h and 24h; density, humidity content. The mechanical properties evaluated were: Tensile strength, static bending (MOR and MOE). The results were compared with NBR 14810-2 (2006) and also with the ANSI A208-1 (1993). The physical performance of these particleboards was below the values recommend by the Brazilian norm. Also the mechanical characteristics are not improve, demonstrating that the inclusion of coffee rind did not benefit the physical characteristics and nor the mechanical ones. However it can be used as construction materials for partitions and ceiling panels.

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Effects of the Variety and Content of Natural Pozzolan Coarse Aggregate on the Thermo-Mechanical Properties of Concrete

Biointerface Research in Applied Chemistry ◽

10.33263/briac124.54055415 ◽

2021 ◽

Vol 12 (4) ◽

pp. 5405-5415

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Compressive Strength ◽

Coarse Aggregate ◽

The Other ◽

Natural Pozzolan ◽

Coarse Aggregates ◽

Natural Aggregate ◽

Middle Atlas

The present study investigated the effects of the variety and content of three natural pozzolan coarse aggregates on concrete. Natural pozzolan aggregates have been obtained from three volcanoes (Boutagrouine, Timahdite, and Jbel Hebri) located in the Middle Atlas region in Morocco. The three pozzolans studied were characterized, and then a comparison was made by replacing the natural aggregate with the pozzolan aggregate in the concrete in different percentages, namely 25, 50, and 100 % in volume. The results showed that the variety and content of pozzolan aggregate have a significant impact on the properties of concrete, primarily caused by the characterization of pozzolan aggregate. The density of concrete decreases with the addition of pozzolan aggregate, which decreases depending on the type of pozzolan aggregate used. The highest compressive strength was measured in the concrete specimens prepared with aggregate BP while the lowest compressive strength was noted in the concrete specimens prepared with aggregate RP. On the other hand, the substitution of NA at 100% by BP, GP, and RP aggregates leads to a decrease in the thermal conductivity of about 67%, 62%, and 55% respectively.

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Atomistic Model of Amorphous Silicon Nitride by Melt-Quench Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.194-196.80 ◽

2011 ◽

Vol 194-196 ◽

pp. 80-83

Author(s):

Ning Bo Liao ◽

Miao Zhang ◽

Rui Jiang ◽

Xi Tao

Keyword(s):

Mechanical Properties ◽

Silicon Nitride ◽

Atomistic Simulation ◽

Chemical Structure ◽

Unique Feature ◽

Amorphous Structure ◽

Amorphous Silicon Nitride ◽

Scale Characterization ◽

Quench Method

Silicon nitride presents good mechanical properties and thermal stability at high temperature. To investigate the mechanism of this unique feature demands a proper atomistic simulation, as the experiments have limitations in nano-scale characterization of chemical structure and the related properties. In this paper, the melt-quench method was used to generate the amorphous structure of silicon nitride, and then the corresponding mechanical properties were studied. The simulation results consist with the experimental results on radial distribution function and Young’s modulus.

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Characterization of Microstructural Susceptibility by Color Tint Etching in a Friction Stir Welded Trip-780 Steel

MRS Proceedings ◽

10.1557/opl.2014.239 ◽

2014 ◽

Vol 1616 ◽

Author(s):

G.Y. Perez-Medina ◽

P. Zambrano ◽

F.A. Reyes-Valdés ◽

H.F. López

Keyword(s):

Mechanical Properties ◽

Plastic Deformation ◽

Tensile Testing ◽

Shear Fracture ◽

Friction Stir ◽

Fine Grain ◽

Lap Shear ◽

Tool Pin ◽

Tension Strength

ABSTRACTThe effect of friction stir welding (FSW) on the resultant microstructures in the welded nugget (WN), thermo-mechanically affected zone (TMAZ), heat affected zone (HAZ) and base metal (BM) of a TRIP-780 steel was investigated in this work. Color tint etching was used in the welded regions to disclose the exhibited microstructural constituents. In addition, significant fine grain size material was found in the WN regions. It was found that is considered to have experienced severe plastic deformation due to interaction with the welding tool pin lead to a drop in mechanical properties. Lap shear tensile testing indicated that the steel shear tension strength in the welded condition dropped compared with the BM. Microhardness profiles of the welded regions indicated that the hardness in both the WN and TMAZ were relatively elevated suggesting the development of martensite in these regions. In particular, the WN was found to shear fracture with uniformly distributed elongation shear dimples.

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Physico-mechanical characterization of non-stabilized Compressed Earth Blocks

10.5194/egusphere-egu2020-9458 ◽

2020 ◽

Author(s):

Marios Kyriakides ◽

Rafail Panagiotou ◽

Rogiros Illampas ◽

Michalis Tapakoudis ◽

Ioannis Ioannou

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Raw Materials ◽

Capillary Absorption ◽

Ongoing Research ◽

Development Fund ◽

Granular Composition ◽

Compressed Earth Blocks ◽

Earth Blocks

Recent challenges faced by humanity in relation to the ongoing climatic changes around the globe, have led many practitioners and researchers search for new environmentally friendly materials to use in construction, such as earth-based materials. A specific form of an earth-based building material that nowadays receives particular attention is Compressed Earth Blocks (CEBs). CEBs comprise of soil mixed at low moisture content and are formed under high pressure in compression, without firing. The end-products can be non-stabilized, i.e., without any cement or lime added, or stabilized, whereby a small quantity of stabilizer (<12% by weight) is added, mainly for enhancing their mechanical and durability properties. CEBs, particularly the non-stabilized ones, are considered to be less expensive and environmentally friendlier, compared to the traditional fired clay bricks, due to their lower production cost and excellent recyclability potential, which significantly reduces the end-product&#8217;s environmental impact.In Cyprus, CEBs were not used in the past, as the prevailing earth building technique on the island was adobe masonry. Recently, however, there appears to be an interest in the use of this material for contemporary construction. The work hereby presented is part of an ongoing research project that focuses on the design, production and characterization of a sustainable and eco-friendly prototype CEB masonry system that will be fabricated using raw materials originating from Cyprus. The project is funded by the European Regional Development Fund and the Republic of Cyprus, through the Cyprus Research and Innovation Foundation (Project ENTERPRISES/0618/0007).In the framework of the aforementioned project, various types of locally sourced soils, with different mineralogical/granular composition and plasticity characteristics have been selected and used for the production of non-stabilized CEBs. A series of tests, including particle-size analysis, Atterberg limits determination, shrinkage and compaction measurements, and X-ray diffraction analyses have been carried out to determine the characteristics of the raw materials selected. In addition, compression and 3-point bending tests, capillary absorption measurements and thermal conductivity analyses have been conducted to assess the physico-mechanical properties of the CEBs produced.XRD analyses have shown that the soils investigated are mainly composed of carbonates and silicates at different ratios. Preliminary capillary absorption tests have demonstrated that the use of a non-reactive liquid, such as acetone, is better over water in determining the sorptivity of non-stabilized CEBs. In addition, the thermal conductivity of all specimens ranged between 0.60-0.85 W/mK. Finally, the results suggest that, despite the different granular composition of the soils used, all soils demonstrated adequate mechanical properties in terms of compressive (over 5 MPa) and flexural (over 0.5 MPa) strength. &#160;

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Effect of High Temperature on Mechanical Properties of Geopolymer Mortar

MATEC Web of Conferences ◽

10.1051/matecconf/201816306004 ◽

2018 ◽

Vol 163 ◽

pp. 06004 ◽

Cited By ~ 3

Author(s):

Mateusz Sitarz ◽

Izabela Hager ◽

Joanna Kochanek

Keyword(s):

Mechanical Properties ◽

High Temperature ◽

Fly Ash ◽

Cement Mortar ◽

Raw Materials ◽

Thermal Exposure ◽

Amorphous Structure ◽

Secondary Mineral ◽

Mineral Raw Materials ◽

Interesting Alternative

The advent of modern aluminosilicate binders has resulted in practical uses for fly ash, which belongs to the group of secondary mineral raw materials; this provides an interesting alternative to cementitious binders, which have a large carbon footprint. Geopolymers mineral binders with a growing range of applications in construction. Their inorganic, amorphous structure endows them with better resistance to high temperature compared to cementitious binders. In this study, the alkaline activation of aluminosilicate Połaniec Fly Ash made it possible to obtain noncementitious material with compressive strength of 18.5 MPa. The article presents the results of a comparison of characteristics of geopolymer mortar and Portland cement mortar after thermal exposure.

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SILICA PURIFICATION FORM MERAPI VOLCANO SAND AS PHOTOVOLTAIC RAW MATERIALS

Jurnal Sains Dasar ◽

10.21831/jsd.v4i2.9087 ◽

2016 ◽

Vol 4 (2) ◽

pp. 122

Author(s):

Sulistiyani Sulistiyani ◽

Erfan Priyambodo ◽

Larasti Yogantari

Keyword(s):

Raw Materials ◽

Amorphous Structure ◽

Raw Material ◽

Silica Sand ◽

Purification Process ◽

Merapi Volcano ◽

Aqua Regia ◽

Photovoltaic Technologies

Purification of silica sand volcanic Mount Merapi has been done, for raw material photovoltaic. Leaching purification process is done using aqua regia solution, H2SO4, and HCl. Purification of silica sand of Mount Merapi as a raw material photovoltaic assumes that photovoltaic technologies that utilize solar energy is quite affordable, do not run out, and clean so that it will provide long term benefits are substantial. Stage purification process through grinding up to size 60 mesh, iron using magnetic separation, leaching of acid and alkaline leaching. Characterization of the samples using XRD and XRF. The result showed that Mount Merapi volcanic sand containing silica is high at 48-50%. XRD characterization results indicate that the silica in sand samples well as silicon dioxide or mineral has amorphous structure. Among aqua regia, H2SO4 and HCl leaching that has the ability to nicest namely the concentration of concentrated HCl and purified silica has a purity of 59%. Keywords: purification, silica, volcano sand

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Mechanical properties and metallurgical characterization of FSPed TIG and TIG welded AA5052-H32/AA5083-H111 dissimilar aluminium alloys

Metallurgical Research & Technology ◽

10.1051/metal/2021005 ◽

2021 ◽

Vol 118 (3) ◽

pp. 304

Author(s):

Antony Prabu Dhanaraj ◽

Subbaiah Kumarasamy

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Optical Microscope ◽

Sem Analysis ◽

Strength Analysis ◽

Friction Stir ◽

Fine Grain ◽

Grain Structures ◽

Metallurgical Characterization

This work describes the mechanical properties and metallurgical characterization of Friction Stir Processing (FSP) on TIG welded dissimilar AA5052-H32 and AA5083-H111 alloys using ER5356 filler wire. A comparison is drawn between unprocessed TIG weld and FS Processed (FSPed) TIG welded specimen with the identical combination. The fabricated welded joints were investigated By Optical Microscope (OM), Scanning Electron Microscope (SEM) Analysis, Tensile Strength Analysis, and Micro-Hardness testing. The results illustrate the improvement in mechanical properties after FSPed of the TIG welded joint resulting in enhanced tensile strength (224.5 MPa) and hardness (104 HV) in contrast to the unprocessed TIG weld joints with (192.5 MPa) and (70 Hv). In addition, during the mechanical characterization, the FSPed TIG welds show fine grain at the Friction Stir (FS) processed zone with fine grain structures which improves the hardness at the FS zone. The mechanical property of FS joint is superior when compared to the unprocessed TIG weld joint.

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