Silicon Dioxide Content Research Articles

Sorption action of silicon-containing samples against bacteria

Silicon-containing amorphous substances, such as silicon dioxide (silica) and aluminosilicates, have a wide range of applications due to their porosity, chemical inertness and thermal stability. These materials are conventionally produced from quartz, diatomite and silicates of various compositions. However, the existing methods for isolating pure compounds are quite expensive and energy intensive. Renewable biological waste containing large amounts of silicon, e.g. rice husks and straw (Oryza sativa), can be used as an alternative raw material. The main advantages of such a material consist in its low cost, almost constant chemical composition, as well as simple and relatively inexpensive processing methods. Due to the high content of silicon dioxide in rice husks and straw, their recycling products are effective adsorbents of many types of pollutants from aqueous solutions. Although some publications describe interaction processes between microorganisms and highly-dispersive synthetic materials based on silicon dioxide of mineral origin, there is a lack of information on the biogenic forms of silica and aluminosilicates obtained from rice production wastes. In previous studies, we established the ability of a number of silicon-containing samples isolated from rice production wastes, depending on the raw material (husk or straw) and production conditions, to bind different bacteria, e.g. Escherichia coli, Streptococcus aureus, Candida albicans, Pseudomonas aeruginosa and Bacillus subtilis. In this work, we studied the sorption action of amorphous silicon dioxide and aluminosilicates obtained from rice husks and straw against the test cultures of Escherichia coli and Bacillus subtilis. The reference materials were such commercial products as expanded vermiculite (natural aluminosilicate) and the ‘White Coal’ sorbent containing approximately equal proportions of silica and microcrystalline cellulose. The obtained results were discussed in the context of the physicochemical parameters of the studied substances, including their chemical composition, IR absorption spectra, characteristics of the acid-base properties of the surface assessed by the methods of pH-metry and adsorption of acid-base indicators (Hammett's method). It was established that the sorption capacity of a sorbent in relation to bacteria depends on the initial material, its composition and production method.

Production of High-Purity Silica Sand from Ivorian Sedimentary Basin by Attrition without Acid Leaching Process for Windows Glass Making

To produce high-purity silica sand usable for glass making, the present study was carried out. The objective of this work was to increase the silicon dioxide (SiO2) content to at least 99% using a simple process without chemical input. The raw sand samples were taken from the Ivorian sedimentary basin, from Maféré and Assinie areas, Côte d’Ivoire. Wet sieving and attrition technique were used for the purification process. The results from the energy dispersive spectrometer (EDS) analyses of the raw and treated samples show a significant increase of silica content and a significant reduction of impurities. The silica content (SiO2) of the sand of Maféré increases from 98.73% ± 0.15% to 99.92% ± 0.05%. And the sand of Assinie increased from 98.82% ± 0.67% in the raw samples to 99.44% ± 0.27% after treatment. The rate of iron oxide and alumina is reduced in these sands. Moreover, the sand of Maféré contains 53.2% of grains of size lower than 500 microns and that of Assinie contains 29.30%. Regarding the chemical composition of these purified sands, they meet the standard BS2975s, the American Ceramic Society and the National Bureau of Standards for window glass making.

Модифицирование межфазного слоя армированных полимерных композитов нанодисперсным диоксидом кремния

The behavior of colloidal silicon dioxide in a composition with a styrene / butyl acrylate oligomer, grafted onto a thermoplastic polyamide adhesive to obtain a branched binder structure with penetration of branches into the capillary-pore system of the reinforcing fiber component, was studied. The variants of disaggregation of SiO2 using ultrasonic treatment and mechanical activation with exposure by high shear stresses, ultrasound and cavitation are compared. Methods of dynamic light scattering, IR spectroscopy, thermal analysis, and textile materials science were used to evaluate the elastic-deformation properties of duplicated packets. The set of complementary results confirms that the combined mechanical activation of an aqueous dispersion of oligoacrylate and silica causes the destruction of silica nanospheres and the formation of a hybrid oligolymer-inorganic adduct. In contrast to the short-term effects of ultrasonic dispersion of SiO2, joint mechanical activation of the components solves the problems of preventing aggregation of nanoparticles and uniform distribution of the reinforcing filler in the composite. The effectiveness of using the method for regulating the properties of forming units and parts of sewing products is shown. When selecting oligoacrylate, specific for sewing production separation of the stages of preliminary bonding of materials using thermoplastic adhesive, the creation of a finished product form and its fixing during wet-heat treatment, is taken into account. The preparation of a hybrid adduct of mechanical activation provides an optimal ratio of particle size for rational distribution of fractions in interfacial, interfiber, and intrafiber spaces of the textile web. The shift of the peaks of phase transitions and chemical transformations in a system with nanodispersed SiO2, controlled on DSC thermograms, is consistent with the temperature regimes of successive stages of the technological process. The possibilities of a controlled change in the properties of forming composite materials and a decrease in the material consumption of sewing products by grafting a modified oligoacrylate with a variable content of silicon dioxide are demonstrated.

Oxidative Destruction of Bitumen in the Presence of Minerals

The oxidation of BND 50/70 bitumen in the presence of minerals is investigated by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The minerals present are quartz, calcite, hornblende, oligoclase, orthoclase perthite, potassium–sodium feldspar, muscovite, and granite. Analysis in terms of the thermal effect indicates that, in the range 200–340°C in an air flux, the oxidation (oxidative aging) of bitumen is 6–10 times faster in the presence of the minerals. With increase in silicon-dioxide content and decrease in calcium-oxide content in the minerals, the oxidation rate of the bitumen significantly increases.

Determining the composition of therapeutic mud and sewage sludge of mud baths for their subsequent disposal

The composition and characteristics of therapeutic mud and sewage sludge of mud baths are studied in the article. The use of the X-ray fluorescence method makes it possible to determine the composition and percentage of elements in the resulting waste of mud baths. The studies are carried out using a sample of natural therapeutic mud from the Sulfatnoe Lake of the Kurgan Region and natural sewage sludge generated after treatment. The study of the elemental composition of natural mud and sludge have shown a high content of silicon dioxide, aluminium oxides, as well as compounds of calcium, magnesium and other elements. Possible options for the disposal of waste mud and sludge by using them in various industries, such as road construction, agriculture, production of structural materials, are proposed. Based on the results of the study, the article also concludes that it is possible to use the sludge in the construction industry.

Synergistic inhibition effect and mechanism of polycation and polyanion on colloidal silica

The silica inhibition of Reverse osmosis (RO) membrane can be treated by adding scale inhibitor. The polycation adipic acid/amine-terminated polyethers D230/diethylenetriamine copolymer (AA/AT/DE) was found to be an effective silica scale inhibitor. The drawback of this scale inhibitor is that small amounts of SiO2 -AA/AT/DE white insoluble floc appear in the solution during the inhibition process. In this study, polyepoxysuccinic acid (PESA) was added to solve this problem. The scale inhibition efficiency of different combinations was tested by static screening tests. The content of silicon dioxide was determined by silicomolybdate spectrophotometric method. In a certain dose range (< 50 ppm), the introduction of PESA can improve the inhibition performance of AA/AT/DE, while, it will have a negative impact when the concentration of PESA was increased to 50 ppm. Based on zeta potential and atomic force microscopy (AFM) topographical analyses, the effect of polycation on the formation of silica particles and the mechanism of the synergistic effect of AA/AT/DE and PESA were placed attention on.

Features of the Charge State of UHMWPE + α-SiO2 Nanocomposites

This paper presents the results into the study of electret properties of composite materials based on ultrahigh molecular weight polyethylene (UHMWPE) and nano-dispersed amorphous silica filler α-SiO2 (aerosil) depending on the volume content of silicon dioxide and the absorbed dose D γ-irradiation at room temperature using the method of thermally stimulated depolarization (TSD). It was found that introducing up to 5% of spherical nanoparticles of amorphous α-SiO2 silicon dioxide with a diameter of 20 nm in UHMWPE first increases and then reduces the electret characteristics of the composites. UHMWPE + 1% α-SiO2 has the maximum value of the electret potential difference and the stability of the electret state. It was shown that preliminary γ-irradiation affects the electret properties of the studied composite material, which is associated with its increased electrical conductivity and a high charge relaxation rate. The observed increase in the initial surface charge density σel of UHMWPE compositions is associated with the presence of energy traps of injected charge carriers. Based on the analyzing the spectra of TSD, it was shown that the thermal stability of electrets from the UHMWPE composite + 1% α-SiO2 is improved. The nature of the TSD current of pre-γ-irradiated films once again proves that, after γ-irradiation, the injected charges from the corona zone mainly accumulate in the near-surface layers of the irradiated samples. The results of TSD suggest that the relaxation of the electret state in the materials under study occurs due to the bulk conductivity.

Influence of silicon dioxide nanoparticles on dielectric relaxation of triglycine sulfate

This study is devoted to clarifying the influence of silicon dioxide nanoparticles on dielectric relaxation properties of classical ferroelectric triglycine sulfate at frequencies of 102÷107Hz in ferroelectric phase. A mixed composite at different composition mass ratios was synthesized. It was indicated that relaxation frequency of triglycine sulfate inclusion decreased as compared to that of its single crystals and shifted toward lower frequencies with silicon dioxide content increase. The linear dispersion region characteristic for single crystals of triglycine sulfate was expanded. The obtained anomalies were explained based on the assumption of strong interaction between composite components through hydrogen bonds.

Acid-base properties of silicon-containing compounds isolated from horsetails (&lt;i&gt;Equisetum Equisetaceae&lt;/i&gt;)

The results of a study into the acid-base surface properties of four silicon-containing ash samples obtained from the above-ground part of the field horsetail plant species ( E. arvense L. ) are presented. The samples were derived according to various schemes, comprising oxidative roasting both with and without preliminary treatments involving water and solutions of hydrochloric acid having a concentration of 0.1 and 1.0 mol/l. It was shown that the content of silicon dioxide in the samples varies from 33 to 98 % depending on the conditions of processing of raw materials. Preliminary processing of the raw material with an acid solution prior to roasting results in the formation of ash having a high silicon oxide content. The main impurity elements are calcium, potassium, magnesium, aluminum and iron. Samples prepared without preliminary treatment, as well as those treated with water, are characterised by a large amount of alkaline earth metal- and potassium oxides. A comparative characteristic of the surface condition of the obtained ash samples is given using pH measurements and the Hammett acidity function method. The pH measurements allow the integral acidity of the surface to be evaluated, while the Hammett method, based on the selective adsorption of acid-base indicators, is used to study the distribution of surface centres by acid-base properties. The pH values of the aqueous suspensions of neutral, alkaline or acidic samples are determined depending on the plant tissue processing scheme. It was found that the surface of the samples is characterised by the presence of Lewis acid- (pKa +16.8), Bronsted basic- (pKa +7.15; +9.45) and acid- (pKa +2.5) active sites, the amount of which is determined by the composition of the samples. The high content of Lewis acid sites in the ash is associated with silicon atoms. The number of Bronsted sites depends on the horsetail treatment scheme. On the surface of samples obtained by oxidative roasting and those pretreated with water, the number of Bronsted active sites at pKa +2.5 and pKa +9.45 is higher compared to ash isolated following hydrolysis with hydrochloric acid. A comparative characteristic of the distribution curves of acid-base centres of silicon-containing ash samples obtained from the above-ground parts of field horsetail and rice straw is given, indicating their similarity.

The role of purity level in foundry silica sand on its thermal properties

Silica sand is the most commonly used mineral for molding and core making applications in foundry technology due to its availability, thermal and chemical attributes. However, there are many additional requirements foundry sands need to meet regarding their sizing, chemical purity, physical durability and thermal properties. This research studies the thermophysical properties of a foundry silica sand comprehensively. After separating one sand batch into numerous grain size ranges, the chemical composition and thermophysical properties of the fractions were investigated, respectively. By means of this approach, the chemical properties and thermal behavior can be directly linked. The silicon dioxide content shows a strong correlation with the thermal expansion properties of the various fractions. The results give a better understanding of the high temperature behavior of foundry silica sands and clarify the role of factors affecting their thermophysical properties.

Mechanical, Thermal and Morphological Characterization of Basalt Fibre Composite- A Review

In fibre reinforced polymers as well as fibre reinforced mortar, basalt fibre has been made an important replacement to glass, polymeric fibre and steel after its exploration. Now a day’s BF (Basalt Fibre) has shown a rise in its attention as a replacement for glass and CF (Carbon Fibre). Basalt is a type of rock mainly dark coloured volcanic rock, which is formed after cooling lava from the volcano. In the production of fibre, basalt rocks having SiO2 (Silicon Dioxide) content of 46% is mainly used. Although basalt rock is found having various proportion of materials, only particular type of basalt rocks is used. The recently develop BFRP (Basalt Fibre Reinforced Polymer) manufactured from naturally occurring volcanic rooks shows tremendous advantages for example its recyclable, eco-friendly or does not harm the eco-system, consumes less energy in productions and as compared other types of FRP, has high performance to cost ratio. Therefore, pertaining to these advantages basalt fibre reinforced fibre has become a more reliable material to use in civil works or buildings various infrastructure. As steel material comes in contact to the corrosion, BFRP is preferred over steel as it has resistance to chemical corrosion as well as it is light weight also.

ДОСЛІДЖЕННЯ КІНЕТИКИ ТЕРМІЧНОГО РОЗКЛАДАННЯ РИСОВОГО ЛУШПИННЯ ПІСЛЯ ВИДАЛЕННЯ ЛІГНІНУ

The study addresses the problem of using recycled materials for the production of a wide range of diverse products; in this context, the paper investigates the extractin of amorphous silicon (IV) dioxide from rice waste, i.e. rice husk, which differs in its chemical composition from all other cereal crops by a high content of silicon dioxide. Amorphous silicon (IV) oxide is widely used in electronics, medicine, food industry, cosmetology, paintwork materials manufacturing, and other industries. Amorphous silicon(IV) oxide has to meet various requirements, the main ones being amorphous structure, degree of purification, and particle size. A derivatographic method of analysis is used to study the non-isothermal kinetics of rice husk residue thermal decomposition. According to the results of derivatographic, chemical, and phase analyzes, a method for amorphous silicon (IV) oxide extraction by thermal decomposition of rice husk after the lignin removal has been proposed. The values of relative activation energies and the pre-exponential factors of the reactions have been calculated. A mathematical model characterized by a system consisting of three first order differential equations and four algebraic equations has been designed. Through the use of the proposed model, the time response characteristics of the process have been studied.

Effect of waste glass powder addition on properties of alkali-activated silica fume mortars

In cement technology, sustainable-based politics demands the use of industrial by-products and waste – based materials. Glass powder (GP) and silica fume (SF) are excellent solid materials to develop a sustainable cement-based material due to a high content of silicon dioxide (SiO2) in their chemical compositions. This study focuses on the properties of alkali-activated silica fume (AASF) mortars containing waste glass powder (WGP). For this purpose, WGP was utilized as partial replacement of sand in AASF mortar mixtures at four levels: 0%, 15%, 30%, and 45% by weight. Displacement -controlled compressive and flexural strength tests were carried out on prismatic 40 × 40 × 160 mm test samples that had been cured for 2,7 and 28 days. The Mercury Intrusion Porosimetry (MIP) test and the thermal conductivity coefficient measurement were carried out following the compressive strength test on 28-day samples. The microstructure morphology and mineralogical properties of the mortar samples were studied by means of Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD), respectively. Experimental studies have shown that at a replacement level of 30%, WGP simultaneously improves the flexural strength of mortars by 12.65% and reduces the thermal conductivity coefficient by 30.88% under stable macro pores and transient capillary–micro pores formation in AASF pore structure. As an alternative to conventional cement mortar, WGP-incorporated AASF mortars attract a great deal of attention.

Development of novel 3D scaffolds using BioExtruder by the incorporation of silica into polycaprolactone matrix for bone tissue engineering

Development of three-dimensional (3D) scaffolds has acquired a great importance for bone repair and tissue reconstruction. Thus, this paper addresses the development of 3D scaffolds by varying the content of silicon dioxide (SiO2) in polycaprolactone (PCL) matrix. The scaffolds were fabricated by employing a novel fused deposition modelling technique (BioExtruder). The physicochemical properties of the developed 3D scaffolds were systematically studied using various techniques. The thermal properties and stability of the PCL and its composites were assessed using differential scanning calorimetry and thermogravimetric analysis. The morphology of the developed scaffolds was evaluated using scanning electron microscopy and optical microscopy, and found that the pore size was increased from 270 to 320 μm with increasing the SiO2 content in the PCL matrix. The wettability of the developed scaffolds was assessed using contact angle meter. The scaffold incorporating 15 wt% of SiO2 exhibited the highest hydrophilic property as well as thermal stability. The Young’s modulus value determined using universal testing machine indicated that the scaffold developed with 15 wt% of SiO2 exhibits 101.59 MPa. To assess the performance of the scaffolds for tissue engineering applications, the in-vitro cytotoxicity and cell proliferation were systematically carried out using L929 Mouse Fibroblasts and MG63 Osteoblasts, respectively. It was found that the scaffolds did not show any toxic effects towards the cell growth, and the cell proliferation was greatly increased >90% during 7 days of cell culture. Based on the results, it is concluded that the scaffold containing 15 wt% of SiO2 is of potential candidate for bone tissue engineering application.

Geometric analysis of dielectric failures in polyimide/silicon dioxide nanocomposites

Polyimide/silicon dioxide nanocomposites were tested for their dielectric strength against nanofiller concentrations between 0% and 14%. The sol–gel process was used for in situ generation of silicon dioxide nanoparticles in a polyamic acid host matrix. Spin‐coated and imidized samples with approximately 15 μm in thickness were then subjected to dielectric breakdown measurements in accordance with ASTM standards. Results showed two distinct regimes of dielectric strength. Higher dielectric withstand capability of nearly 275 kV mm−1 was exhibited by samples with 0% and 2% silicon dioxide. Higher concentration samples were dielectrically weaker by approximately 45% at 150 kV mm−1. Broken‐down specimens were examined under optical and electron microscopes. An inverse relationship between nanoparticle concentration and breakdown perforation diameter was observed. Hole sizes decreased gradually from 140 to 40 μm as silicon dioxide content increased from 0% to 6% and ultimately settled near 30 μm with higher concentrations. The testing results, examined through failure analysis, were explained by breakdown behaviors and mechanisms at different size scales. The findings from this project, in context with previous works and theories, can help establish connections of dielectric strength, perforation diameter, and nanofiller concentration for future polymer nanocomposite research. POLYM. ENG. SCI., 59:1897–1904, 2019. © 2019 Society of Plastics Engineers

The effect of oil palm shell ash to asphalt characteristics

This study aims to determine the effect of the addition of oil palm shell ash on the characteristics of asphalt and its mixtures. Palm shell is chosen as a filler material due to its content of silicon dioxide (SiO2) so that it is used as a suitable binder. This study consisted of several stages: (1) making modified bitumen; (2) testing modified bitumen with asphalt physical requirements method; (3) making and testing specimens; (4) Marshall testing. The results showed that the addition of oil palm shell ash resulted in increased asphalt stability values with the highest stability of 1553 kg from sample 4. Furthermore, the addition of oil palm shell ash resulted in increased asphalt flow values with the highest flow of 3,85 mm from sample 5. Based on the results of the research and discussion, it was concluded that there was an effect of the addition of oil palm shell ash on the characteristics of asphalt and its mixture.

Кремнийсодержащие соединения в составе хвощей (Equisetum Equisetaceae)

The article presents the results of a chemical and phase composition study of ash obtained from the aerial parts of three horsetail species growing in different regions of Primorsky Krai, namely forest (Equisetum sylvaticum L.), wintering (Equisetum hyemale L.) and field (Equisetum arvense L.) horsetail. It is shown that the conditions for processing raw materials affect the content of silicon dioxide (32–98%) in the ash residues. X-ray phase analysis has shown that the amorphous or amorphous-crystalline state of ash residues depends on the conditions of their production. The absorption bands typical for amorphous silicon dioxide are observed in the IR spectra of ash samples, which correspond to bending (467 cm-1 ) and stretching vibrations (802 and 1092 cm-1 ) of Si-O-Si siloxane bonds. The elemental analysis of silicon-containing products indicates an increase of silicon dioxide content in the samples with an increase in acid concentration during the processing of the aerial part of the horsetails, which also depends on the plant species: the field horsetail contains the lowest quantity of SiO2 as compared to the forest and wintering horsetails, but is characterised by a high content of potassium and calcium compounds. The sorption characteristics of ash obtained from the aerial part of horsetails are assessed: iodine adsorption capacity (5–42%) and methylene blue (164–260 mg/g) and methyl orange (40–241 mg/g) organic dye adsorption capacities. The obtained information can be used in the development of sorbents from vegetable raw materials for the purification and after-purification treatment of natural and waste waters from pollutants of various types.

Structural Characterizations of Aluminosilicates in Two Types of Fly Ash Samples from Shanxi Province, North China

In order to determine the structural characterization of aluminosilicates in two types of fly ashes, two samples from Shanxi Province, China were selected for study. One was from a pulverized coal boiler (FA-1), and the other from a circulating fluidized bed boiler (FA-2). FA-1 had a much higher content of silicon dioxide (SiO2) (70.30%) than FA-2(42.19%), but aluminum oxide (Al2O3) was higher in FA-2 (25.41%) than in FA-1 (17.04%). The characterizations were investigated using various methods including X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), magic angle spinning nuclear magnetic resonance (MAS–NMR) spectrometry, and X-ray photoelectron spectroscopy (XPS). The XRD analysis showed that FA-1 contained aluminosilicate glass, quartz and mullite, while FA-2 contained significant amounts of amorphous aluminosilicate, quartz and gypsum. The FTIR results showed an increased substitution of Al3+ for Si4+ as the band of asymmetric stretching vibrations Si–O(Si) (1100 cm−1) moved to 1090 cm−1 for FA-2, much lower than for FA-1(1097 cm−1). Moreover, the sharpness of the bands in the 1250–1000 cm−1 region for FA-2 indicates that the silicate structure of FA-2 was more ordered than for FA-1. It can be understood from the 29Si MAS–NMR results that Q4(mAl) (Q4 are connected via 4 bridging O atoms to mAl) is the main structural type in FA-1 and FA-2, and that FA-2 contains more Al, which substitutes for Si in the Q4 structure. 27Al MAS–NMR demonstrated that a combination of tetrahedral, pentahedral, and octahedral Al existed in FA-1 and FA-2. The Si 2p XPS spectra suggested that there were three forms of Si, including bridging Si (Si–O2), non–bridging Si (Si–O), and SiO2 gel. The content of Si–O2 for FA-1 was 37.48% higher than Si–O (28.57%), while the content of Si–O2 was 30.21% lower than Si–O (40.15%) for FA-2. The Al 2p XPS spectra showed that octahedral Al was the dominant form for FA-1 with a content of 40.25%, while the main phase was tetrahedral Al for FA-2 with a proportion of 37.36%, which corresponds well with the 27Al MAS–NMR results.

Isothermal Kinetic Mechanism of Coke Dissolving in Hot Metal

The carburization of molten iron is close to saturation in the blast furnace process, while that in the flash ironmaking process is uncertain because there is no pressure from solid charge and no carburization reactions occurring between the deadman and hot metal. Some experiments were conducted to reveal the kinetic mechanism of coke dissolving in carbon-iron melts. Reduced iron powder, electrolytic iron as well as chemical pure graphite were used as experiment materials. With high-purity argon injected as the protective gas, the specimens were heated up to 1873 K in a tubular resistance furnace to study the isothermal mechanism. The results show that the composition of the ferrous sample affects the dissolution rate. When the FeO content of the iron-bearing material rises from 0% to 4.76%, the apparent dissolution rate constant, kt, falls from 7.98 × 10−6 m/s to 5.48 × 10−6 m/s. There are some differences amongst the dissolution rate coefficients of different cokes despite interacting with similar carbon-iron melts, with coke 1 of 7.98 × 10−6 m/s, coke 2 of 5.17 × 10−6 m/s, and coke 3 of 3.77 × 10−6 m/s. Besides, this index decreases with the increase of the dissolution time and solely depends on the procedure of the mass transfer. A negative correlation is demonstrated between kt and the sulfur content in the iron bath as well. The content of silicon dioxide in the coke has a significant influence on kt. Additionally, the dissolution rate coefficient increases with the increase of the graphitization degree of coke.

Influence by chemical constitution of aggregates on demulsification speed of emulsified asphalt based on UV-spectral analysis

Emulsified asphalt as an indispensable raw material for pavement engineering construction is subjected to various combinations of aggregates and varying environmental conditions leading to uncontrollable demulsification speed. In this respect, this research examined the influence of chemical composition of aggregate on emulsified asphalt demulsification speed. Three representative types of domestic road limestone aggregates with various appearances were studied by chemical analysis method. Experimental results indicate that the Magnesium oxide, alumina, calcium oxide, ferric oxide and silicon oxide were the main chemical compositions of limestone aggregate and their contents varied significantly among different types of aggregate. Ultraviolet spectrophotometry was used to evaluate effects of each chemical component on the demulsification speed of emulsified asphalt. Results indicate that mixing ratio of chemical components has a significant effect on demulsification speed of asphalt emulsion. Magnesium oxide accelerated the demulsification speed of emulsified asphalt, while calcium oxide showed an opposite trend. Iron oxide, alumina and silica had little effect on the speed of demulsification. Finally, grey correlation analysis was performed, and a clear relationship was established. The results which are expressed as the magnesium oxide, alumina, iron oxide and silicon dioxide content with differing ratio in the aggregate affected significantly on the demulsification speed of emulsified asphalt. However, there is no clear relationship between the demulsification speed and emulsified asphalt when the ratio of the calcium oxide content is changed.