scholarly journals Production of agroindustrial ashes with pozzolanic activity via acid leaching, conjugated burning and ultrafine grinding

2020 ◽  
Vol 20 (4) ◽  
pp. 189-203
Author(s):  
Guilherme Chagas Cordeiro ◽  
Mônica Nunes Lemos ◽  
Kristian Vinco Xavier ◽  
Charles Prado Ferreira de Lima
Keyword(s):  
Mechanical Performance ◽  
Isothermal Calorimetry ◽  
Acid Leaching ◽  
Chemical Characterization ◽  
Raw Material ◽  
Hydration Kinetics ◽  
Cement Pastes ◽  
Ultrafine Grinding ◽  
Physical And Chemical

Abstract This paper aims to study the production and the physical and chemical characterization of rice husk, sugarcane bagasse, corn straw, and bamboo leaf ashes to use as pozzolans. The ash production steps basically consisted of raw material collection, chemical treatment by citric acid leaching, conjugated burning (thermal processing) and ultrafine grinding (mechanical processing) of the produced ashes. The results indicated that all ashes could be classified as pozzolanic additions based on specific standards. The high pozzolanicity of the ashes was confirmed by testing the electrical conductivity, mechanical performance index, and hydration kinetics of cement pastes by isothermal calorimetry. Therefore, the production processes used in this work were effective in producing highly reactive pozzolanic materials.

scholarly journals Influence of Ultrasonication of Functionalized Carbon Nanotubes on the Rheology, Hydration, and Compressive Strength of Portland Cement Pastes

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5248
Author(s):  
Laura Silvestro ◽  
Artur Ruviaro ◽  
Geannina Lima ◽  
Paulo de Matos ◽  
Afonso R. G. de Azevedo ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strength ◽  
Portland Cement ◽  
Mechanical Performance ◽  
Isothermal Calorimetry ◽  
Hydration Kinetics ◽  
Cement Pastes ◽  
Degree Of Hydration ◽  
Vis Spectroscopy ◽  
Localized Defects

The functionalization process usually increases the localized defects of carbon nanotubes (CNT). Thus, the ultrasonication parameters used for dispersing non-functionalized CNT should be carefully evaluated to verify if they are adequate in dispersing functionalized CNT. Although ultrasonication is widely used for non-functionalized CNT, the effect of this dispersing process of functionalized CNT has not been thoroughly investigated. Thus, this work investigated the effect of ultrasonication on functionalized CNT + superplasticizer (SP) aqueous dispersions by ultraviolet-visible (UV-Vis) spectroscopy, dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FTIR). Furthermore, Portland cement pastes with additions of 0.05% and 0.1% CNT by cement weight and ultrasonication amplitudes of 0%, 50% and 80% were evaluated through rheometry, isothermal calorimetry, compressive strength at 1, 7 and 28 days, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). FTIR results from CNT + SP dispersions indicated that ultrasonication may negatively affect SP molecules and CNT graphene structure. The increase in CNT content and amplitude of ultrasonication gradually increased the static and dynamic yield stress of paste but did not significantly affect its hydration kinetics. Compressive strength results indicated that the optimum CNT content was 0.05% by cement weight, which increased the strength of composite by up to 15.8% compared with the plain paste. CNT ultrasonication neither increases the degree of hydration of cement nor the mechanical performance of composite when compared with mixes containing unsonicated CNT. Overall, ultrasonication of functionalized CNT is not efficient in improving the fresh and hardened performance of cementitious composites.

scholarly journals Castor oil based polyurethane adhesive content on OSSB produced with soybean straw

2021 ◽  
Vol 21 (1) ◽  
pp. 23-36
Author(s):  
João Vitor Felippe Silva ◽  
Maria Fernanda Felippe Silva ◽  
Bruno Santos Ferreira ◽  
Juliano Fiorelli ◽  
André Luis Christoforo ◽  
...  
Keyword(s):  
Castor Oil ◽  
Mechanical Performance ◽  
Chemical Properties ◽  
Chemical Characterization ◽  
Physical And Mechanical Properties ◽  
Polyurethane Adhesive ◽  
European Standards ◽  
Soybean Straw ◽  
Physical And Chemical

Abstract Oriented Structural Straw Board (OSSB) panels are composites made from straw originally from agricultural residues and non-formaldehyde based adhesive, whose main application is for construction as a closing and ceiling material. The objective of this study was to evaluate the effect of the polyurethane adhesive content on physical and mechanical properties of OSSB produced with locally available SbS (soybean straw). Four castor oil based polyurethane ratios (6%, 9%, 12% and 15%, by mass of the SbS) were tested. OSSB was evaluated according to European standards for wood-based composites; also, a physical and chemical characterization of the SbS was performed. SbS has an irregular shape, which reduced the OSSB mechanical performance due to the low densification of the composite and the development of transversal cracks on the SbS after the OSSB manufacturing process. The static bending and thickness swelling performance of SbS OSSB was not improved by the increase of polyurethane adhesive content. SbS low ash content and neutral pH extractives indicates that probably its chemical properties should not affect the setting of the adhesive.

scholarly journals Physical and Chemical Characterization of an Oyster Hemagglutinin

1969 ◽  
Vol 244 (15) ◽  
pp. 4128-4135
Author(s):  
R T Acton ◽  
J C Bennett ◽  
E E Evans ◽  
R E Schrohenloher
Keyword(s):  
Chemical Characterization ◽  
Physical And Chemical Characterization ◽  
Physical And Chemical

Physical and Chemical Characterization of Asphalt (Bitumen) Paving Exposures

2007 ◽  
Vol 4 (sup1) ◽  
pp. 209-216 ◽  
Author(s):  
Robert F. Herrick ◽  
Michael D. McClean ◽  
John D. Meeker ◽  
Leonard Zwack ◽  
Kevin Hanley
Keyword(s):  
Chemical Characterization ◽  
Physical And Chemical Characterization ◽  
Physical And Chemical

scholarly journals Physical and chemical characterization of masa and tortillas from parental lines, crosses, and one hybrid

2017 ◽  
Vol 31 (1) ◽  
pp. 129-138 ◽  
Author(s):  
C. Valderrama-Bravo ◽  
A. Domínguez-Pacheco ◽  
C. Hernández-Aguilar ◽  
R. Zepeda-Bautista ◽  
A. del Real-López ◽  
...  
Keyword(s):  
Grain Quality ◽  
Chemical Characterization ◽  
Starch Granules ◽  
Grain Hardness ◽  
Crude Fiber Content ◽  
Viscoelastic Parameters ◽  
Maize Genotypes ◽  
Quality Product ◽  
Physical And Chemical

Abstract In maize plant breeding aimed at producing a hybrid, it is necessary to characterize the parents and hybrids by their agronomic aspects and grain quality so that the processing industry may offer consumers a quality product and also improve its efficiency. This study evaluated the viscoelastic parameters of masa and the chemical and texture properties of tortillas obtained from parent lines (M-54, M55, and CML-242), two single crosses (M54xM55 and M55xM54), and one hybrid (H-70). The morphology of the maize grains and tortillas was analyzed using scanning electron microscopy. The firmness of masa obtained from CML-242 and H-70 maize was higher than that from the other maize genotypes. M-54 tortillas showed the lowest crude fiber content. Otherwise, tortillas obtained from the M55xM54 hard grain had the lowest fat content and extensibility, while H-70 tortillas showed an intermediate breaking point and extensibility. M-54 and M54xM55 tortillas were softer due to their more swollen starch granules. In contrast, rigid tortillas were obtained from CML-242 and H-70. Grain hardness causes different morphology in starch and tortilla of maize genotypes. However, grain hardness did not influence the characteristics of texture in tortillas.

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