Biopolymer-Based Hybrids as Effective Admixtures for Cement Composites

In the framework of this publication, silica-lignin hybrid materials were designed, obtained, characterized and then used as admixtures for cement composites. High-energy mechanical grinding of individual components was used to produce the systems that allowed ensuring adequate homogeneity of the final products. As a result of the analysis of Fourier transform infrared spectroscopy, it has been confirmed that weak physical interactions occur between the components. This allowed classifying the resulting systems as I class hybrid materials. In addition, the efficiency of obtaining final products was also inferred on the basis of obtained porous structure parameters and colorimetric data. The achieved bio-admixture with different weight ratios of silica and lignin was added to cement pastes in the amount ranging from 0.5 to 1 wt.%. The study showed that increasing the ratio of lignin in the admixture from 0.15 to 1 wt.% had a positive effect on the rheological properties of the pastes, while the mechanical properties of the composite were deteriorated. In turn, a higher amount of silica in the admixture acted in reverse. The most favorable results were obtained for a silica-lignin bio-admixture with a weight ratio of components equal to 5:1 wt./wt. A significant increase in compressive strength was gained at satisfactory plasticity of the paste.

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Concept of Evaluation of Mineral Additives’ Effect on Cement Pastes’ Durability and Environmental Suitability

Materials ◽

10.3390/ma14061448 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1448

Author(s):

Robert Figmig ◽

Adriana Estokova ◽

Miloslav Luptak

Keyword(s):

Natural Zeolite ◽

Holistic Approach ◽

Cement Composites ◽

Cement Pastes ◽

Supplementary Cementitious Material ◽

Environmental Suitability ◽

Evaluation Approach ◽

Mineral Additive ◽

Mineral Additives ◽

Positive Effect

This experimental study focuses on the assessment of mineral additives and their incorporation into cement composites (CC). The assessment was based on a holistic approach to the performance of the durability properties of CC. Environmental suitability was also taken into consideration. In the experiments, cement pastes with w/c ratios of 0.3, 0.4, and 0.5, respectively, were prepared. Natural zeolite (NZ) and densified silica fume (SF) at doses of 7.5 and 15.0 wt.% of cement were used as the investigated (replacement) materials. Their effects (including development over time) on density, strength (flexural and compressive), porosity by water absorption, permeability by rapid chloride penetration (RCP) test, phase content by thermal analysis, and hydration progression, were observed. The results were then used to propose an evaluation approach. Natural zeolite was used for its known pozzolanic activity and classification as a supplementary cementitious material (SCM). In contrast SF acted as a filler in cement pastes, and thus did not have a direct positive effect on durability. The concept of comprehensive analysis for unknown additive classification is proposed to expressly differentiate between SCM, inert, and improving mineral additive. This concept could be applied to the assessment of mineral additives with regards to the durability and suitability of cement composites.

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Rheology of Cement Pastes with Siliceous Fly Ash and the CSH Nano-Admixture

Materials ◽

10.3390/ma14133640 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3640

Author(s):

Bartosz Szostak ◽

Grzegorz Ludwik Golewski

Keyword(s):

Fly Ash ◽

Modern Technology ◽

Heat Of Hydration ◽

Hydration Heat ◽

Cement Composites ◽

Standard Samples ◽

Cement Pastes ◽

Positive Effects ◽

Calcium Silicates ◽

Positive Effect

The use of fly ash in cement composites adversely affects its mechanical properties during the first days of mixture curing. Modern technology, in the form of an admixture containing the hydrated calcium silicates, allows to accelerate the hardening and binding process of concrete. In this paper, studies on the influence of the admixture on properties of concretes with the ordinary Portland cements (OPC) containing the addition of siliceous fly ash (FA) have been carried out. As part of the experimental research, the authors conducted a series of studies for cement pastes modified with the addition of FA and the CSH nano-admixture (NA). In order to compare the mixtures, the following tests of cement pastes were carried out: the compressive and flexural strength, heat of hydration, SEM and rheological shrinkage. The mechanical parameters were tested after 4, 8, 12 and 24 h. The hydration heat test and microstructure analysis were carried out during the first 24 h of the concrete curing. All tests were carried out on the standard samples. On the basis of the heat of hydration test, much higher hydration heat was found in mixtures modified with the NA. During the shrinkage test, a positive effect of the NA was observed—the shrinkage during the first 28 days of mixture curing was lower than in the reference samples. The application of the CSH nano-admixture to cement pastes with the addition of FA has brought positive effects. Apart from a significant increase in strength in the first 24 h of mixture curing, a reduction in the rheological shrinkage was observed. The admixture can be successfully used in the ash concretes, in which a higher early strength is required.

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Effect of Boron and Carbon Addition on the Phase Transformations during High-Energy Ball Milling and Subsequent Sintering of Si3N4+B and Si3N4+C Powder Mixtures

Materials Science Forum ◽

10.4028/www.scientific.net/msf.869.58 ◽

2016 ◽

Vol 869 ◽

pp. 58-63

Author(s):

Luiz Otávio Vicentin Maruya ◽

Bruna Rage Baldone Lara ◽

Belmira Benedita de Lima ◽

Vanessa Motta Chad ◽

Gilberto Carvalho Coelho ◽

...

Keyword(s):

Phase Transformations ◽

Ball Milling ◽

Weight Ratio ◽

High Energy ◽

Ceramic Composites ◽

Nitrogen Atmosphere ◽

Carbon Addition ◽

Powder Mixtures ◽

X Ray ◽

Milled Powders

This study reports on effect of boron and carbon addition on the phase transformations during ball milling and subsequent sintering of Si3N4+B and Si3N4+C powder mixtures. Ball milling at room temperature was conducted using stainless steel vials (225 mL) and balls (19mm diameter), 300 rpm and a bal-to-powder weight ratio of 10:1. The as-milled powders were uniaxially compacted in order to obtain cylinder samples with 10 mm diameter, which were subsequently sintered under nitrogen atmosphere at 1500°C for 1h. Characterization of the as-milled powders and sintered samples was performed by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. Only peaks of Si3N4 were identified in X-ray diffractograms of as-milled Si3N4+B and Si3N4+C powders, suggesting that metastable structures were found during milling. After sintering at 1500°C for 1h, the Si3N4+BN and Si3N4+SiC ceramic composites were formed from the mechanically alloyed Si3N4+B and Si3N4+C powders.

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Transmural distribution of metabolic abnormalities and glycolytic activity during dobutamine-induced demand ischemia

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01383.2007 ◽

2008 ◽

Vol 294 (6) ◽

pp. H2680-H2686 ◽

Cited By ~ 1

Author(s):

Mohammad N. Jameel ◽

Xiaohong Wang ◽

Marcel H. J. Eijgelshoven ◽

Abdul Mansoor ◽

Jianyi Zhang

Keyword(s):

Blood Flow ◽

Coronary Stenosis ◽

Energy Demand ◽

Weight Ratio ◽

Dry Weight ◽

High Energy ◽

Left Ventricular ◽

Cardiac Work ◽

Induced Demand ◽

Systolic Thickening

The heterogeneity across the left ventricular wall is characterized by higher rates of oxygen consumption, systolic thickening fraction, myocardial perfusion, and lower energetic state in the subendocardial layers (ENDO). During dobutamine stimulation-induced demand ischemia, the transmural distribution of energy demand and metabolic markers of ischemia are not known. In this study, hemodynamics, transmural high-energy phosphate (HEP), 2-deoxyglucose-6-phosphate (2-DGP) levels, and myocardial blood flow (MBF) were determined under basal conditions, during dobutamine infusion (DOB: 20 μg·kg−1·min−1 iv), and during coronary stenosis + DOB + 2-deoxyglucose (2-DG) infusion. DOB increased rate pressure products (RPP) and MBF significantly without affecting the subendocardial-to-subepicardial blood flow ratio (ENDO/EPI) or HEP levels. During coronary stenosis + DOB + 2-DG infusion, RPP, ischemic zone (IZ) MBF, and ENDO/EPI decreased significantly. The IZ ratio of creatine phosphate-to-ATP decreased significantly [2.30 ± 0.14, 2.06 ± 0.13, and 2.04 ± 0.11 to 1.77 ± 0.12, 1.70 ± 0.11, and 1.72 ± 0.12 for EPI, midmyocardial (MID), and ENDO, respectively], and 2-DGP accumulated in all layers, as evidenced by the 2-DGP/PCr (0.55 ± 0.12, 0.52 ± 0.10, and 0.37 ± 0.08 for EPI, MID, and ENDO, respectively; P < 0.05, EPI > ENDO). In the IZ the wet weight-to-dry weight ratio was significantly increased compared with the normal zone (5.9 ± 0.5 vs. 4.4 ± 0.4; P < 0.05). Thus, in the stenotic perfused bed, during dobutamine-induced high cardiac work state, despite higher blood flow, the subepicardial layers showed the greater metabolic changes characterized by a shift toward higher carbohydrate metabolism, suggesting that a homeostatic response to high-cardiac work state is characterized by more glucose utilization in energy metabolism.

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High-Energy Ball Milling and Sintering of Ti-2Ta-22Si-11B and Ti-6Ta-22Si-11B Powders Mixtures

Materials Science Forum ◽

10.4028/www.scientific.net/msf.802.20 ◽

2014 ◽

Vol 802 ◽

pp. 20-24 ◽

Cited By ~ 2

Author(s):

Lucas Moreira Ferreira ◽

Luciano Braga Alkmin ◽

Érika C.T. Ramos ◽

Carlos Angelo Nunes ◽

Alfeu Saraiva Ramos

Keyword(s):

Ball Milling ◽

Weight Ratio ◽

High Energy ◽

Milling Process ◽

Wet Milling ◽

X Ray Diffraction ◽

Heat Treated ◽

Equilibrium Structures ◽

Rotary Speed ◽

Steel Balls

The milling process of elemental Ti-2Ta-22Si-11B and Ti-6Ta-22Si-11B (at-%) powder mixtures were performed in a planetary Fritsch P-5 ball mill using stainless steel vials (225 mL) and hardened steel balls (19 mm diameter). Ball-to-powder weight ratio of 10:1 and a rotary speed of 300 rpm were adopted, varying the milling time. Wet milling (isopropyl alcohol) for 20 more minutes was used to increase the yield powder in to the vial. Following the Ti-Ta-Si-B powders milled for 600 min were heat-treated at 1100°C for 1 h in order to obtain the equilibrium structures. The milled powders and heat-treated samples were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. Supersaturated Ti solid solutions were formed during ball milling of Ti-Ta-Si-B powders while that the Ti5Si3 phase was formed after milling for 620 min of the Ta-richer powder mixture only. The particles sizes were initially increased during the initial milling times, and the wet milling provided the yield powder into the vials. A large amount of pores was found in both the sintered samples which presented the formation of the TiSS,(ss-solid solution) Ti6Si2B and TiB.

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DESIGN OF CEMENT COMPOSITES WITH INCREASED IMPERMEABILITY

Vestnik MGSU ◽

10.22227/1997-0935.2016.5.72-81 ◽

2016 ◽

pp. 72-81

Author(s):

Roman Sergeevich Fedyuk

Keyword(s):

Composite Materials ◽

Cement Composite ◽

Vapor Permeability ◽

Cement Stone ◽

Cement Composites ◽

Hydrated Cement ◽

Body Density ◽

Scale Levels ◽

Positive Effect ◽

Improved Characteristics

The paper deals with the development of composite binders for producing concrete with improved characteristics of gas, water and vapor permeability. The authors investigate the processes of composite materials formation in order of decreasing scale levels from macro to nanostructures. The criteria for optimization of the volume of dispersed additives in concrete are offered. The authors theoretically studied the technological features of the formation of hydrated cement stone structure. A positive effect of nanodispersed additives on the structure and physico-mechanical properties of cement composite materials are predicted. Thanks to its improved features, such as good ratio of strength and body density, high density and lifetime, the modified concrete may be used when solving various practical tasks of the construction branch.

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Effect of Calcination Temperature on Performance of Photocatalytic Reactor System for Seawater Pretreatment

BULLETIN OF CHEMICAL REACTION ENGINEERING AND CATALYSIS ◽

10.9767/bcrec.11.2.554.230-237 ◽

2016 ◽

Vol 11 (2) ◽

pp. 230 ◽

Cited By ~ 1

Author(s):

Weerana Eh Kan ◽

Jamil Roslan ◽

Ruzinah Isha

Keyword(s):

Photocatalytic Activity ◽

Calcination Temperature ◽

Energy Demand ◽

Weight Ratio ◽

Oxygen Demand ◽

High Energy ◽

Reactor System ◽

Impregnation Method ◽

Seawater Desalination ◽

Photocatalytic Reactor

Conservative desalination technology including distillation requires high energy and cost to operate. Hence, pretreatment process can be done prior to desalination to overcome energy demand and cost reduction. Objective of this research is to study the effect of calcination temperature of hybrid catalyst in photocatalytic reactor system in the seawater desalination, i.e. salt removal in the seawater. The catalyst was synthesized via wet impregnation method with 1:1 weight ratio of TiO2 and activated oil palm fiber ash (Ti:Ash). The catalyst was calcined at different temperature, i.e. 500 oC and 800 oC. The study was carried out in a one liter Borosilicate photoreactor equipped with mercury light of 365 nanometers for two hours with 400 rpm mixing and catalyst to seawater sample weight ratio of 1:400. The Chemical Oxygen Demand (COD), pH, dissolved oxygen (DO), turbidity and conductivity of the seawater were analyzed prior and after the testing. The fresh and spent catalysts were characterized via X-Ray Diffractogram (XRD and Nitrogen physisorption analysis. The calcination temperature significantly influenced the adsorption behaviour and photocatalytic activity. However, Ti:Ash which calcined at 800 oC has less photocatalytic activity. It might be because the surface of fiber ash was sintered after calcined at high temperature. The Ti:Ash catalyst that calcined at 500 oC was found to be the most effective catalyst in the desalination of seawater by reducing the salt concentration of more than 9 % compared to Ti:Ash calcined at 800 oC. It can be concluded that catalyst calcination at 500 °C has better character, performance and economically feasible catalyst for seawater desalination. Copyright © 2016 BCREC GROUP. All rights reservedReceived: 22nd January 2016; Revised: 23rd February 2016; Accepted: 23rd February 2016How to Cite: Kan, W.E., Roslan, J., Isha R. (2016). Effect of Calcination Temperature on Performance of Photocatalytic Reactor System for Seawater Pretreatment. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (2): 230-237 (doi:10.9767/bcrec.11.2.554.230-237)Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.2.554.230-237

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Enhancement of Thermal and Sound Insulation Properties of Cement Composite Roofing Tile by Addition of Nanocellulose Coated Pineapple Fiber and Modified Rubber Tire Waste

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.861.465 ◽

2020 ◽

Vol 861 ◽

pp. 465-472

Author(s):

Kanokon Hancharoen ◽

Parames Kamhangrittirong ◽

Pimsiree Suwanna

Keyword(s):

Weight Ratio ◽

Cement Composite ◽

Sound Insulation ◽

Type I ◽

Cement Composites ◽

Water To Cement Ratio ◽

Rubber Particles ◽

Reduction Coefficient ◽

Rubber Cement ◽

Better Than

In this work, the enhancement of thermal and sound insulation properties of cement composite roofing tile with nanocellulose coated pineapple fiber and modified waste tire rubber is studied. The composite was composed of bacterial nanocellose (BNC) coated pineapple fibers, modified rubber particles, platicizer and type I Portland cement in the weight ratio of 10:50:0.8:100 with the water to cement ratio (w/c) of 0.5. The thermal conducitity of the fiber rubber cement composite could be reduced to 0.1080 ± 0.0048 W/m.K as opposed to 0.3810 ± 0.0041 and 0.5860 ± 0.0050 W/m.K for the fiber cement and the rubber cement composites, respectively. Moreover, the noise reduction coefficient of the fiber rubber cement composite could be increased to 0.2832 as opposed to 0.2143 and 0.1899 for the fiber cement and the rubber cement composites, respectively. These results revealed that adding nanocellulose coated pineapple fiber and modified rubber particles together to the cement composite can enhance the thermal insulation and sound absorption abilities of the composite roof tile significantly better than adding each constituent separately.

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Effect of Graphene Oxide on Mechanical Properties of Cement Mortar and its Strengthening Mechanism

Materials ◽

10.3390/ma12223753 ◽

2019 ◽

Vol 12 (22) ◽

pp. 3753 ◽

Cited By ~ 7

Author(s):

Yahui Wang ◽

Jiawen Yang ◽

Dong Ouyang

Keyword(s):

Mechanical Properties ◽

Graphene Oxide ◽

Cement Hydration ◽

Strengthening Mechanism ◽

Cement Composites ◽

Working Mechanism ◽

Cement Pastes ◽

Cement Mortars ◽

Binder Ratio ◽

Growth Space

The effects of the water–binder ratio and different graphene oxide (GO) sizes on the mechanical properties of GO-cement composites were systematically studied by preparing GO-cement mortars. The scanning electron microscopy observation (SEM) of the surface and fracture surface of cement pastes was carried out to study the morphology of cement hydration crystals in GO-cement systems under different space conditions. It was found that GO nanosheets significantly improved the compressive, flexural, and tensile strengths of cement mortars. When the dosage of GO nanosheets was 0.03% by weight of cement, the compressive, flexural, and tensile strengths at 28 days increased by 21.37%, 39.62%, and 53.77%, respectively, but GO was not found to be able to regulate the formation of flower-like cement hydration crystals. It was only shown that the growth space had an important influence on the morphology of hydrates. A possible working mechanism was proposed by which GO nanosheets prevented the expansion of microcracks in the cement pastes via a shield effect, thus enhancing the strength and toughness of the cement composites.

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Effect of Milling Speed on the Synthesis of In-Situ Cu-25 Vol. % WC Nanocomposite by Mechanical Alloying

Jurnal Teknologi ◽

10.11113/jt.v59.2599 ◽

2012 ◽

Vol 59 (2) ◽

Author(s):

Nurulhuda Bashirom ◽

Nurzatil Ismah Mohd Arif

Keyword(s):

Stainless Steel ◽

Mechanical Alloying ◽

Weight Ratio ◽

High Energy ◽

Milling Process ◽

Nominal Composition ◽

X Ray Diffraction ◽

The Matrix ◽

Steel Balls

This paper presents a study on the effect of milling speed on the synthesis of Cu-WC nanocomposites by mechanical alloying (MA). The Cu-WC nanocomposite with nominal composition of 25 vol.% of WC was produced in-situ via MA from elemental powders of copper (Cu), tungsten (W), and graphite (C). These powders were milled in the high-energy “Pulverisette 6” planetary ball mill according to composition Cu-34.90 wt% W-2.28 wt% C. The powders were milled in different milling speed; 400 rpm, 500 rpm, and 600 rpm. The milling process was conducted under argon atmosphere by using a stainless steel vial and 10 mm diameter of stainless steel balls, with ball-to-powder weight ratio (BPR) 10:1. The as-milled powders were characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). XRD result showed the formation of W2C phase after milling for 400 rpm and as the speed increased, the peak was broadened. No WC phase was detected after milling. Increasing the milling speed resulted in smaller crystallite size of Cu and proven to be in nanosized. Based on SEM result, higher milling speed leads to the refinement of hard W particles in the Cu matrix. Up to the 600 rpm, the unreacted W particles still existed in the matrix showing 20 hours milling time was not sufficient to completely dissolve the W.

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