Search results

1 – 10 of 288
To view the access options for this content please click here
Article
Publication date: 1 April 1998

E.A.M. Youssef, Nivin M. Ahmed and M.A. Abd El‐Ghaffar

Silica waste fume is a byproduct produced in the manufacture of ferrosilicon. The sample, which was very fine and rich in silica, was characterized using chemical and…

Abstract

Silica waste fume is a byproduct produced in the manufacture of ferrosilicon. The sample, which was very fine and rich in silica, was characterized using chemical and spectrophotometric measurements (XRD and electron microscope). The silica fume was incorporated in anticorrosive paint formulations based on alkyd resin to replace partially or completely the imported diatomaceous silica. The various paint formulations were evaluated and the physico‐mechanical properties as well as the corrosion protection properties of the painted films have been studied. Promising results were achieved, which showed that silica fume can replace satisfactorily the imported diatomaceous silica from the economical and environmental points of view.

Details

Pigment & Resin Technology, vol. 27 no. 2
Type: Research Article
ISSN: 0369-9420

Keywords

To view the access options for this content please click here
Article
Publication date: 4 August 2020

Salwa H. El-Sabbagh, Nivin M. Ahmed, Doaa Samir Mahmoud and Wael S. Mohamed

The purpose of this paper is to evaluate the efficiency of commercial silica, silica fume-waste (SF) and modified silica fume-waste (mSF) as reinforcing filler in…

Abstract

Purpose

The purpose of this paper is to evaluate the efficiency of commercial silica, silica fume-waste (SF) and modified silica fume-waste (mSF) as reinforcing filler in acrylonitrile-butadiene rubber (NBR) and ethylene propylene diene monomer (EPDM) through the mixing process of rubber. The composites were prepared using different loadings of silica fume and commercial silica in EPDM and NBR composites. Structural characterization of silica and SF was done using X-ray fluorescence and scanning electron microscopy (SEM). The surface of silica fume waste was modified using poly methyl methacrylate/butyl acrylate through emulsion polymerization to increase the interaction between silica and rubber, then consequently better dispersion in rubber matrix was obtained. The mSF waste was characterized using FT-IR spectra and transmission electron microscopy.

Design/methodology/approach

The investigated rubber mixes and vulcanizates were evaluated by measuring the curing characteristics, mechanical testing, thermogravimetric analysis and morphological studies (SEM). The mechanical properties of composites including tensile strength, elongation at break and modulus were estimated and analyzed.

Findings

The results revealed that the composites (NBR and EPDM) containing mSF as filler exhibited better rheological and mechanical properties compared to unmodified silica waste and commercial silica. The SEM analysis indicated that the mSF was homogeneously dispersed through the surface of NBR and EPDM composites. Also, results showed that (NBR and EPDM) composites exhibited remarkable improvements in tensile strength, elongation at break and hardness in the presence of mSF; they also showed an increase in the thermal stability. This means that the treatment of surface SF can improve its dispersion in rubber.

Research limitations/implications

Silica cannot be applied in rubber matrix without surface modification because of their incompatibility; their dispersion is not good without surface modification.

Practical implications

The modified silica surface is considered as effective reinforcing filler which can replace other fillers because of its lower surface energy and enhanced intercalating behavior in rubber.

Social implications

This study is just a start in establishing rubber projects with wide applications in the industry and providing a cheap local product while preserving the quality and that is the use of factory waste, which helps in protecting the environment from pollution.

Originality/value

mSF is cheap with relatively high purity, which make rubber/mSF composites appear as new grade of material that can be used in different media rather than rubber.

Details

Pigment & Resin Technology, vol. 50 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

To view the access options for this content please click here
Article
Publication date: 27 July 2018

Nivin M. Ahmed, Mostafa G. Mohamed, Reham H. Tammam and Mohamed R. Mabrouk

This study aims to apply novel anticorrosive pigments containing silica fume-phosphates (Si-Ph), which were prepared using core-shell technique by covering 80-90 per cent…

Abstract

Purpose

This study aims to apply novel anticorrosive pigments containing silica fume-phosphates (Si-Ph), which were prepared using core-shell technique by covering 80-90 per cent silica fume (core) with 10-20 per cent phosphates (shell) previously, to play dual functions simultaneously as anticorrosive pigments in coating formulations and as an anticorrosive admixture in concrete even if it is not present in the concrete itself. Two comparisons were held out to show the results of coatings on rebars containing core-shell pigments in concrete, and concrete admixtured with silica fume can perform a dual function as anticorrosive pigment and concrete admixture. The evaluation of corrosion protection efficiency of coatings containing core-shell pigments and those containing phosphates was performed.

Design/methodology/approach

Simple chemical techniques were used to prepare core-shell pigments, and their characterization was carried out in a previous work. These pigments were incorporated in solvent-based paint formulations based on epoxy resin. Different electrochemical techniques such as open-circuit potential and electrochemical impedance spectroscopy were used to evaluate the anticorrosive efficiency of the new pigments.

Findings

The electrochemical measurements showed that concrete containing coated rebars with core-shell pigments exhibited almost similar results to that of concrete admixtured with silica fume. Also, the anticorrosive performance of coatings containing Si-Ph pigments offered protection efficiency almost similar to that of phosphates, proving that these new pigments can perform both roles as anticorrosive pigment and concrete admixture.

Originality/value

Although the new Si-Ph pigments contain more than 80 per cent waste material, its performance can be compared to original phosphate pigments in the reinforced concrete.

Details

Pigment & Resin Technology, vol. 47 no. 4
Type: Research Article
ISSN: 0369-9420

Keywords

To view the access options for this content please click here
Article
Publication date: 16 August 2019

Yasmin Murad, Rana Imam, Husam Abu Hajar, Dua’a Habeh, Abdullah Hammad and Zaid Shawash

The purpose of this paper is to develop new predictive models using gene expression programming in order to estimate the compressive strength of green concrete, as…

Abstract

Purpose

The purpose of this paper is to develop new predictive models using gene expression programming in order to estimate the compressive strength of green concrete, as accurate models that can predict the compressive strength of green concrete are still lacking.

Design/methodology/approach

To estimate the compressive strength of plain concrete, fly ash concrete, silica fume concrete and concrete with silica fume and fly ash, four predictive GEP models are developed. The GEP models are developed using a large and reliable database that is collected from the literature. The GEP models are validated using the collected experimental database.

Findings

The R2 is used to statistically evaluate the performance of the GEP models wherein the R2 values for the GEP models including all data are 85, 95, 80 and 95.3 percent for the models that predict the compressive strength of plain concrete, fly ash concrete, silica fume concrete and concrete with silica fume and fly ash, respectively.

Originality/value

The GEP models have high R2 values and low RMSE and MAE, which indicates that they are capable of predicting the compressive strength of green concrete with a reasonable accuracy.

Details

International Journal of Structural Integrity, vol. 11 no. 2
Type: Research Article
ISSN: 1757-9864

Keywords

To view the access options for this content please click here
Article
Publication date: 2 May 2017

Nivin M. Ahmed, Walaa M. Abd El-Gawad, Ahmed A. El_Shami and Eglal M.R. Souaya

This study aims to synthesize a series of new anticorrosive pigments using a new technique called “core-shell”. This technique is based on depositing thin surface layer of…

Abstract

Purpose

This study aims to synthesize a series of new anticorrosive pigments using a new technique called “core-shell”. This technique is based on depositing thin surface layer of expensive, efficient anticorrosive pigment on a cheap extender. This extender forms the bulk of the new pigments. The new pigments were constructed on cores of either waste silica fume or kaolin comprising 80-85 per cent of their chemical structure, and the ferrite shell was about of 20-15 per cent. Electrochemical studies were undertaken on two series of pigments for comparison between ferrites/silica fume and ferrites/kaolin pigment to show their performance, as the shells are different.

Design/methodology/approach

The different ferrites/silica fume and ferrites/kaolin pigments were characterized using different analytical and spectrophotometric techniques, such as X-ray fluorescence (XRF) and transmission electron microscopy (TEM). Immersion test and electrochemical impedance measurements were done in 3.5 per cent NaCl.

Findings

The tests revealed that paint films containing Sr ferrite/silica and Ca ferrite/kaolin were the most effective in corrosion prevention.

Practical implications

Silica fumes have a large array of uses. These pigments can be applied in various industries such as painting, wooding coating, anti-corruption coating, powder coating, architectural paint and waterproof paints. Treated kaolin can be applied in many industries besides pigment manufacture and paint formulations; it can be applied as a reinforcing filler in rubber, plastics and ceramic composites.

Originality/value

The new pigments are considered ecofriendly materials, because using them converts a waste product and a natural ore to useful marketable product, leading to reducing cost and saving the environment at the same time.

Details

Pigment & Resin Technology, vol. 46 no. 3
Type: Research Article
ISSN: 0369-9420

Keywords

To view the access options for this content please click here
Article
Publication date: 5 March 2018

Nivin M. Ahmed, Walaa M. Abd El-Gawad and Eglal M.R. Souaya

Core-shell is structured particles having several chemical compositions. The advantage of these particles arise from their specific design, to be used in decreasing costs…

Abstract

Purpose

Core-shell is structured particles having several chemical compositions. The advantage of these particles arise from their specific design, to be used in decreasing costs by using inexpensive material (natural ore or waste material) as carrier for thin shell of active material. This study aims to prepare ferrites/silica core-shell pigments and compare their inhibition efficiency to original ferrites. These pigments have shells of different ferrites that comprise 10-15 per cent of the prepared pigments on silica fume. Silica fume which is the core is a byproduct in the ferro–silicon industry; this core comprises 85-90 per cent of the prepared pigments.

Design/methodology/approach

The prepared core-shell pigments were characterized using transmission electron microscopy analysis, energy-dispersive X-ray analysis and sequential wavelength dispersive X-ray fluorescence. These pigments were integrated in epoxy-based paint formulations, and the physical, mechanical and corrosion properties of dry films were examined. The corrosion properties were studied by using immersion test in 3.5 per cent NaCl for 28 days.

Findings

This study showed that these new eco-friendly and inexpensive pigments are similar to ferrites in their inhibition performance, i.e. they exhibited high corrosion prevention.

Research limitations/implications

Domestic waste materials were reused in paints and only simple modification was used, and then, their effectiveness showed similar performance to that of the original pigments.

Originality/value

Ferrite and ferrite/silica pigments are environmentally friendly pigments that can replace other hazardous pigments (e.g. chromates) with almost the same quality in their performance; also, they can be used in industries other than paints (e.g. paper, rubber and plastics composites).

Details

Pigment & Resin Technology, vol. 47 no. 2
Type: Research Article
ISSN: 0369-9420

Keywords

To view the access options for this content please click here
Article
Publication date: 27 May 2014

Li Tang, Philip Shapira and Yu Meng

This paper aims to explore pathways and issues of small business technological commercialization in China, probing the particular characteristics of the Chinese context…

Abstract

Purpose

This paper aims to explore pathways and issues of small business technological commercialization in China, probing the particular characteristics of the Chinese context and the ways in which innovation frameworks, institutions and business strategies are embedded.

Design/methodology/approach

The authors examine in detail the case of an innovative Chinese indigenous small firm engaged in innovative nanotechnology materials development. The strategies and push- and pull factors underlying the company’s innovation practices were investigated. The proposition that the institutional relationships formed to secure access to research expertise and aid business survival also influence the ways in which technology is commercialized was explored.

Findings

It was found that while technological development is company-driven, it is also highly connected to regional innovation structures and networks. This stimulates a “spin-in” rather than a university-led model of development, as this small firm embeds its technology and business development strategies in conjunction with partner organizations. Broader management and policy implications are discussed.

Originality/value

While China has rapidly expanded scientific research in emerging technologies such as nanotechnology, commercialization through the development of entrepreneurial technology-oriented small companies faces a series of challenges. New enterprises in the emerging area of nanotechnology encounter problems of technology transfer and intellectual property management, capital acquisition, market uncertainty and constrained access to global markets.

Details

Chinese Management Studies, vol. 8 no. 2
Type: Research Article
ISSN: 1750-614X

Keywords

To view the access options for this content please click here
Article
Publication date: 1 February 1993

Despite recessionary years in 1990 and 1991, West European demand for specialty silicas has increased at an average annual rate of 8% per year over the past five years as…

Abstract

Despite recessionary years in 1990 and 1991, West European demand for specialty silicas has increased at an average annual rate of 8% per year over the past five years as detailed in a new study from Kline and Company. In 1991, total European demand reached $425 million for the eight silica products listed in Table 1. These silicas, which include both synthetically manufactured products as well as natural minerals, are used in a wide variety of industrial and consumer applications. Specialty silicas impart such unique functions as reinforcement, thickening or electrical properties to these applications and are not used merely as cost reducing fillers.

Details

Pigment & Resin Technology, vol. 22 no. 2
Type: Research Article
ISSN: 0369-9420

To view the access options for this content please click here
Article
Publication date: 9 April 2018

Babak Zareiyan and Behrokh Khoshnevis

This paper aims to investigate the strength at interlayer of specimens fabricated using Contour Crafting (CC) to develop a concrete mixture for large-scale…

Downloads
293

Abstract

Purpose

This paper aims to investigate the strength at interlayer of specimens fabricated using Contour Crafting (CC) to develop a concrete mixture for large-scale three-dimensional printing.

Design/methodology/approach

The collected data from several experiments were analyzed to understand significant factors and their interactions. After developing the empirical model, condition for maximum desirability was identified and the model was validated.

Findings

The experimental investigation of varied combination of concrete components introduced an empirical model which can predict the strength at interface. Moreover, an optimized mixture within constrains of the CC nozzle was developed and validated.

Originality/value

Several experimental samples were tested, and the derived empirical model was validated after more than 600 h of work.

Details

Rapid Prototyping Journal, vol. 24 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

To view the access options for this content please click here
Article
Publication date: 14 September 2017

Khalid Al-Gahtani, Ibrahim Alsulaihi, Mohamed Ali and Mohamed Marzouk

The purpose of this paper is to highlight the sustainability benefits of using demolition and industrial wastes as a replacement for aggregates and cement in traditional…

Abstract

Purpose

The purpose of this paper is to highlight the sustainability benefits of using demolition and industrial wastes as a replacement for aggregates and cement in traditional concrete mixes.

Design/methodology/approach

Crushed concrete from demolition sites served as a replacement for fine and coarse aggregate in some of the mixes at various ratios. In addition, ground granulated blast furnace slag, metakaolin, silica fume, and fly ash each served as a cement replacement for cement content in the mixes tested in this research at various rates. Compression strength tests, permeability, and thermal expansion tests were performed on various mixes to compare their performance to that of traditional mixes with natural aggregate, and with no cement replacement.

Findings

The compressive strength results indicated the suitability of using such demolition wastes as replacements in producing green concrete (GC) without hindering its mechanical characteristics significantly. In addition, the results indicated an enhancement in the mechanical characteristics of GC when replacing cement with pozzolanic industrial wastes and byproducts.

Originality/value

The research assesses the utilization of sustainable GC using recycled waste aggregate and byproducts.

Details

Built Environment Project and Asset Management, vol. 7 no. 4
Type: Research Article
ISSN: 2044-124X

Keywords

1 – 10 of 288