Percentages Of Nanosilica Research Articles

Effect of surface area of nanosilica particles on the cure kinetics parameters of an epoxy resin system

ABSTRACTKnowing of thermoset curing kinetics is essential for process development, quality control, and achieving desirable products. Hence, in this article, cure kinetics of an EPON 828 epoxy resin/dicyandiamide curing agent/diuron accelerator system is investigated. This resin system is usually used for the production of epoxy/glass fiber prepregs used in wind turbine blades. For this, differential scanning calorimetry analysis is used and the effect of temperature, weight percentage, and size of nanosilica is studied by conducting isothermal tests at several temperatures for samples with and without nanoparticles. An autocatalytic curing model is applied to describe the cure kinetic of system and then the variations in model parameters calculated by curve fitting using the MATLAB software. The results show that the increase in temperature, weight percentage of nanosilica from 0 to 6%, and surface area of nanosilica particles lead to the increase in curing rate, whereas the increase in the percentage and surface area of nanosilica particles significantly decreases total heat of reaction. At the end, the relation between each of model parameters and the total surface area of nanosilica particles, calculated by mathematical equations, is obtained. The allowable maximum surface area of nanosilica used in the mathematical equations is 12 m2 g−1. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47958.

The long-term effects of nano-silica on concrete

The emergence on nanotechnology has driven the advancement of a lot of materials, one of which is nano-silica. Therefore, the research on the application of nano-silica in concrete has been conducted by researchers. The results showed that the strength and durability of concrete can be significantly increased by the application of nano-silica. However, the conducted research was limited to 28 days (short term). Furthermore, nano silica as a new material needs to be tested over a long period of time (more than 28 days) to determine its impact on concrete. Research on the long-term implications of using nano silica was carried out on f’c 45 MPa concrete. The percentage of nano silica used is fixed, at 5% of the weight of the binder. Furthermore, mechanical properties were tested including; compressive strength, tensile strength and slump test of normal concrete at 28, 56 and 91 days of the concrete’age. The results showed that the use of nano silica can increase compressive strength and tensile strength. The results showed that when compared to normal concrete, the use of nano silica can increase compressive and tensile strength and also produce better mechanical properties.

New model of moisture susceptibility of nano silica-modified asphalt concrete using GMDH algorithm

Abstract The primary objectives of the design and implementation of asphalt pavement on road and road surfaces are to achieve the best performance in different climatic conditions. Asphalt pavement performance depends on the adhesion and bonding of binder and aggregates that the moisture causes it to disappear and it results in bleeding and stripping. Although the moisture susceptibility mechanism is not fully known, factors such as binder properties, aggregates properties, asphalt mixture properties, quality control during congestion, the dynamic effect of traffic load and the type of anti-stripping additive play a significant role in creating a moisture susceptibility and aggravation of failures. In this paper, Group Method of Data Handling (GMDH)-type neural networks have been used for modeling and prediction of moisture susceptibility of nano silica-modified asphalt concrete. To achieve this goal, 5 types of mixtures with different percentage of nano-silica (0, 0.2, 0.4, 0.7 & 0.9%) were prepared and the moisture susceptibility of modified mixtures was evaluated. Results showed that nano-silica can improve the moisture susceptibility of asphalt mixtures. For modeling, the experimental data were divided into train and test sections (70% for training and 30% for testing). The predicted values were compared with those of experimental values in order to estimate the performance of the GMDH-neural network. The model values showed a very good regression with the experimental results.

Engineering characteristics of nanosilica/polymer-modified bitumen and predicting their rheological properties using multilayer perceptron neural network model

This study examines the effect of mixing varying percentages of nano-silica (NS), i.e. 2, 4 and 6% (by weight of polymer-modified bitumen, PMB) with PMB, in unaged and aged conditions. The Fourier transform infrared spectroscopy, x-ray diffraction, scanning electron microscopy and dynamic shear rheometer were used to determine chemical, microstructure and rheological properties of the binders, respectively. An artificial neural network (ANN) model, known as the multilayer perceptron neural networks model with three different algorithms namely; Levenberg-Marquardt (LM), scaled conjugate gradient (SCG), and gradient descent with adaptive back propagation (GDA) were used to predict the rheological properties of binders. The results indicate that adding NS to PMB may weaken the binders and delay their ageing. The amorphous structures of NS-PMBs remain unchanged and no new crystalline phase was formed when varying percentages of NS was added to PMB. Extreme heat caused a marked increase in the complex modulus of NS-PMB6 while low temperatures reduced its complex modulus. This resulted in enhanced resistance to the rutting and fatigue parameters. Adding higher amounts of NS particles to PMB also improved the viscoelastic properties and resistance to the ageing conditions of NS-PMB6. In terms of modeling, it was found that the most suitable algorithms and neurons number in the hidden layer for the ANN-Unaged model is LM algorithm and 11 neurons. For ANN-RTFOT and ANN-PAV models, the optimum algorithms and neurons number in hidden layer is SGC algorithm with 11 neurons and LM with 9 neurons respectively. The R-value (>0.95) for all models show a good agreement between measured and predicted data. It was concluded that the ANNs could be used as an accurate, fast and practical method for researchers and engineers to predict the phase angle and complex modulus of NS-PMBs.

Moisture susceptibility of porous asphalt mixture with Nano silica modified asphalt binder

This paper presents the mechanical properties of porous asphalt (PA) with nanosilica (NS) modified asphalt binder in terms of its Moisture Susceptibility. This test is essential to evaluate the performance of NS-PA towards the resistance of moisture induced damage. Moisture susceptibility can be defined as the loss durability, strength and stiffness of PA due to the existence of moisture, causing the adhesive loss of binder and aggregate. It is interesting to know that the existence of nanoparticle with different proportion can affect the moisture susceptibility behavior of NS-PA. Three different percentages of nanosilica were mixed with PEN 60-70 type of binder in this study. Then, all these blended modified binder were used to prepare PA Grading B specimens using Marshall Mix Design Method. Nanoparticle used in this study was Nanosilica with the average size of 10 to 15 nanometer. In addition, Moisture Susceptibility of NS-PA was evaluated using Indirect Tensile Strength Test, based on Modified Lottman Test. From the result, the maximum TSR value obtained at 2% NS-PA, which was 91%. Meanwhile, for conventional PA (0% NS), TSR value was only 74%. In accordance to AASTHOT283, TSR value should be equal or more than 80% to withstand moisture induced damage. However, for PA, 70% TSR value is consider acceptable due to porous nature of PA that permit water to flow inside the mix. From this result, it was concluded that the optimum amount of NS required for PA to withstand moisture induced damage was 2%. Thus, with proper NS concentration, the performance of PA with NS modified binder in terms of moisture susceptibility can be enhanced.

Effect of nano-silica and nano-waste material on durability and corrosion rate of steel reinforcement embedded in high-performance concrete

The corrosion rate of reinforcing steel present in high-performance concrete (HPC) was examined in the presence of nano fly ash, nano-silica fume, and nano coal as nano-waste material (NFA, SF, NC), respectively. A replacement to ordinary Portland cement (OPC) was carried out to some extent with nano-waste materials at 1, 2, 3, 4, 5, and 6% by cement weight to yield the (NFA, NSF, NC) HPC, as well as different percentages of NS (1, 2, 3 and 4%) were used. The corrosion rate of reinforcing steel present in HPC and nano-silica- and nano-waste materials-HPC was monitored and estimated using the half-cell potential (HCP). In addition to, water permeability, water absorption and aggressive attack media (immersed in sewage water) of hardened HPC and nano-silica- and nano-waste materials-HPC were also studied. All the samples of steel reinforcement were immersed in Qaron’s Lake water up to 6 months of exposure. The lowest corrosion rate results, compared with ordinary HPC, were obtained when nano-silica and nano-waste materials were used in concentrations 3,4, 4 and 2% (NS, NFA, NSF, and NC), respectively. Furthermore, HPC implanted with nano-silica (NS) is slightly better results than NFA. From the obtained data, the replacement with NFA gives the best milled waste material compared to NSF and NC, which improve the durability of nano fly ash-HPC.

Properties of nanosilica-reinforced green architectural cement composites incorporating ground granulated blast furnace slag with low activity

The aim of the present study was to investigate the effect of combination of ground granulated blast furnace slag (GGBFS) with low pozzolanic activity index and nanosilica as a highly reactive pozzolan on different properties of cement mortar applicable for architectural purposes. The properties studied include mechanical performances (in terms of compressive and flexural strengths), durability (by electrical resistivity, water absorption, and chloride penetration tests), and microstructural characteristics (through thermogravimetric analysis, X-ray diffraction test, and scanning electron microscopy). The results revealed that the addition of nanosilica could compensate for mechanical strength and durability losses brought about through the utilization of GGBFS with low pozzolanic performance. Considering compressive and flexural strengths, the optimal percentage of nanosilica was 1%; however, the employment of 2% nanosilica performed more efficient concerning durability characteristics. Moreover, synergistic effect of the application of ternary cementitious blends of low pozzolanic activity GGBFS and nanosilica was noticed in the results of compression, electrical resistivity, and rapid chloride penetration tests.

Material design and characterization of pervious concrete reactive barrier containing nano-silica and fine pumice aggregate

In this study, the physical and mechanical properties of pervious concrete (PC) containing nano-silica (NS) was carried out. Mix design based on the Taguchi method in three levels and four factors (water to cement ratio, aggregate to cement ratio, the percentage of nano-silica, and percentage of fine aggregate (FA)) were examined. Concrete properties such as compressive strength, density (D), permeability (P), and porosity were evaluated. Among nine mix designs, the optimum one according to Taguchi optimization results was found from experimental results: (W/C) = 0.26, (A/C) = 5, 6% (NS) and 20% (FA). The corresponding mechanical and physical properties had a compressive strength of 3.6 (MPa), permeability of 1.06 (cm/s), void ratio of 19.7 (%), and density of 879 (kg/m3). Adding NS (up to 6% of cement weight) and FA (up to 20% of aggregates weight) had an important effect on almost all tests especially on CS, and there was no impressive influence related to another factor (W/C, A/C) in all tests. It is noticeable that the influence of adding NS to the mix design on CS was higher than adding FA.

Incorporation mode effect of Nano-silica on the rheological and mechanical properties of cementitious pastes and cement mortars

Previous research indicates that the inclusion of nanosilica (NS) modifies the properties of the fresh and hardened state, compared to the traditional mineral additions. NS decreases the setting times of the cement mortar compared to silica fume (SF) and reduce of required water while improving the cohesion of the mixtures in the fresh state. Some authors estimate that the appropriate percentage of Nano-silica should be small (1 to 5% by weight) because of difficulties caused by agglomeration to particles during mixing, while others indicate that 10% by weight, if adjustments are made to the formulation to avoid an excess of self-drying and micro cracks that could impede strength. For this purpose, the present work aim to see the effect of the introduction mode of the nanosilica on the rheological and physic mechanical properties of cement mortars. In this study, NS was used either powdered with cement or in solution with the superplasticizer (Superplasticizer doped in nanosilica). Results show that the use of nanosilica powder (replacing cement on the one hand) has a negative influence on the rheological parameters and the rheological behavior of cementitious pastes. However, the introduction of nanosilica in solution in the superplasticizer (SP) was significantly improved the rheological parameters and the rheological behavior of cementitious pastes. Indeed, more the dosage of NS-doped SP increases more the shear stress and viscosities of the cementitious pastes become more fluid and manageable. A significant reduction of shear stress and plastic viscosity were observed that due to the increase in superplasticizer. A dosage of 1.5% NS-doped SP gave adequate fluidity and the shear rate was lower.

Acid resistance of quaternary blended recycled aggregate concrete

The possibility of reusing the aggregate from demolished structures in fresh concrete, in order to reduce the CO2 impact on the environment [23] and to preserve natural resources, was explored worldwide and it is established that recycled aggregates can be used as a partial replacement of natural aggregates. Due to its potential to be used in eco-friendly structures and shortage of supply of natural aggregates in some parts of the world, there is an increasing interest in using the recycled aggregate. The durability aspects are also of equal concern along with the strength and economy of any material to be used in the construction. Studies reveal that the behaviour of ternary and quaternary blended concretes is superior from durability point of view compared to conventional concrete. Therefore a study is conducted to assess the acid resistance of recycled aggregate based Quaternary Blended Cement Concrete (QBCC) of two grades M40 and M60. Fly ash and silica fume are fixed at 20% and 10% respectively from the previous studies while two percentages of Nano silica (2 and 3%) were used along with the cement to obtain QBCC. Three percentages of recycled aggregates as partial replacement of conventional aggregate (0%, 50% and 75%) were used in this study. Two different acids (HCL and H2SO4) with different concentrations (3 and 5%) were used in this study. Acid resistance of QBCC with Recycled Concrete Aggregate (RCA) is assessed in terms of visual appearance, weight loss, and compressive strength loss by destructive and non-destructive tests at regular intervals for a period of 56 days. The test results showed marginal weight loss and strength loss in both M40 and M60 grades of concretes. The Ultrasonic Pulse Velocity (UPV) results show that the quality of QBCC is good even after being subjected to acid exposure.

Investigation of the effect of nano-silica on thermal sensitivity of HMA using artificial neural network

Due to changes in weather conditions, engineers try to improve performance characteristics and properties of asphalt mixtures using additives. In this regard, modifiers are used because bitumen cannot have a good performance in all environmental and loading conditions. This paper examined the impact of one of the most efficient and widely used nanomaterials in various industries called nano-silica (Nano SiO2) on the thermal properties of bitumen and asphalt mixture. Using a solution that can reduce the cost and time of assessment is very important. Using artificial neural networks in many cases facilitates operations on data engineering sciences. It is necessary to ensure that a comprehensive study is performed through considering all or most of the parameters affecting the behavior. The aim of this study was to evaluate temperature sensitivity of asphalt mixture modified with nano-silica. To achieve this goal, 5 types of mixtures with different percentage of nano-silica (0, 0.2, 0.4, 0.7 & 0.9%) were prepared and the temperature sensitivity of modified mixtures was evaluated. Results showed that nano-silica can improve the temperature sensitivity of asphalt mixtures. Moreover, the thermal sensitivity of asphalt mixtures modified with nano-silica using artificial neural network and methods of multilayer perceptron (MLP) and radial basis function (RBF) was simulated and analyzed.

Finite-Element Analysis for Surface Discharge Due to Interfacial Polarization at the Oil-Nanocomposite Interface

The propagation of surface discharge due to interfacial polarization was numerically analyzed at the oil-nanocomposite interface using fully coupled finite-element analysis incorporating the relative permittivity from experiments. To improve the insulation ability, a new nanodielectric insulating material has been proposed in which a pressboard is coated with epoxy resin mixed with silica nanoparticles; this nanocomposite material can enhance the breakdown voltage in power systems with a certain level of silica nanoparticles. To specify the electric breakdown performance of this nanocomposite material, we measured the bulk relative permittivity of epoxy resin containing different percentages of silica nanoparticles on the pressboard. Surface discharge, or creepage discharge, tends to propagate along the solid–liquid interface and then leads to flashover. The mechanism of surface discharge, therefore, is a critical issue for understanding the dielectric breakdown strength in solid–liquid interface problems. To quantitatively analyze and explain the characteristics of surface discharge, here, the fully coupled finite-element analysis technique has been applied and tested with various relative permittivity values of nanocomposite materials. This phenomenon has been simulated using the fully coupled governing equations using Poisson’s equation for electric field and charge continuity equations, including surface charge accumulation for charge transport. After verification of our numerical setup in a conventional oil-pressboard system, a needle-bar electrode system was proposed and applied to the analysis of surface discharge propagation for the new nanocomposite materials with bulk dielectric permittivity. The propagation speed at the oil-nanocomposite interface was compared with different percentages of nanosilica. Finally, the physical mechanism of surface discharge due to the interfacial polarization was analyzed with the space, bounded, and surface charge densities at the oil-nanocomposite interface based on the numerical results.

Investigating the creep properties of asphaltic concrete containing nano-silica

This study was aimed at investigating the creep behaviour of a typical asphalt concrete containing different percentages of nano-silica. The penetration grade of 60/70 asphalt cement was modified with different percentages of nano-silica (i.e., 1, 3 and 5%, by the weight) and was used for making the asphalt concrete specimens. The asphalt concrete specimens were subjected to dynamic creep tests. Dynamic creep tests were conducted at different stress levels and temperatures. A three-stage model, developed was fitted to the dynamic creep test results to capture the primary, secondary and the tertiary creep regions, and calculate the flow number and the steady-state strain rate in the secondary creep region. The results showed that, the flow number increased, and the steady-state strain rate decreased with increasing nano-silica content, indicating the increase of resistance against permanent deformation.

Relationship between splitting tensile and compressive strengths for self-compacting concrete containing nano- and micro silica

This paper describes the relationship between splitting tensile strength and compressive strength of self-consolidating concrete using data collected from laboratory specimens tested at standard conditions. The results were then compared with some expressions published in international literature. The investigated variables included: type of cement, percentage of nanosilica and percentage of microsilica as a cement replacement by weight. In spite of concrete not being designed to resist direct tension the knowledge of tensile strength is needed to estimate the cracking load. In the absence of test results an estimate of the tensile strength may be obtained by using the relationship proposed. The verification of the proposed formula based on experimental data was estimated by means of the integral absolute error (IAE). The output of this study has provided a better understanding of the correlation between splitting and compressive strengths of SCCs and the effect of some related variables on the resultant behavior, which has therefore, helped to generate new expression with better accuracy.

Influence of nanosilica on moisture resistance of polymer modified bitumens

ABSTRACTIn this research, the effects of nanosilica and polymer on moisture resistance and other properties of hot mix asphalt have been investigated. The asphalt binder was modified using polyethylene and polypropylene polymers with varying percentages of nanosilica. The Marshall stability, flow, indirect tensile strength, stiffness modulus and resistance to moisture damages test tensile strength ratio (TSR) and retained Marshall stability (RMS) tests were conducted. The results show that application of nanosilica improves the stability, reduces optimum binder content, increases stiffness as well as strength characteristic of the asphalt mixtures. Moisture damage analysis of the modified mixtures shows a good enhancement due to addition of nanosilica particles.

THE ROLE OF CEMENT CONTENT ON CONTROLLING THE COMPRESSIVE STRENGTH AND WATER ABSORPTION OF NANO SILICA CONCRETE

This paper presents an experimental investigation on the effect of Nano Silica (NS) on the compressive strength of concrete made with different cement contents. Two percentages of NS, 1.5% and 3%, as partial replacement of cement were investigated at cement contents of 300, 400, 500 and 600 kg/m3. The effect of NS and cement contents on the compressive strength of concrete at different testing ages of 7, 28 and 56 days was evaluated. The effect of NS and cement contents on the water absorption percentage (WA%) was also investigated. The effect of cement content on the compressive strength ratios at 7 and 56 days to that at 28 days was found and correlated. The effects of cement content on the enhancement ratios of compressive strength and WA% were also evaluated and correlated. NS addition enhanced the compressive strength and reduced the WA%. The maximum enhancement in the compressive strength was recorded at 1.5 % NS. As this ratio increased to 3%, the compressive strength decreased but to a values not less than that of the concrete mix without NS.

Microstructure characteristics of cement-stabilized sandy soil using nanosilica

An experimental program was conducted to explore the impact of nanosilica on the microstructure and mechanical characteristics of cemented sandy soil. Cement agent included Portland cement type II. Cement content was 6% by weight of the sandy soil. Nanosilica was added in percentages of 0%, 4%, 8% and 12% by weight of cement. Cylindrical samples were prepared with relative density of 80% and optimum water content and cured for 7 d, 28 d and 90 d. Microstructure characteristics of cement-nanosilica-sand mixtures after 90 d of curing have been explored using atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests. Effects of curing time on microstructure properties of cemented sandy soil samples with 0% and 8% nanosilica have been investigated using SEM test. Unconfined compression test (for all curing times) and compaction test were also performed. The SEM and AFM tests results showed that nanosilica contributes to enhancement of cemented sandy soil through yielding denser, more uniform structure. The XRD test demonstrated that the inclusion of nanosilica in the cemented soil increases the intensity of the calcium silicate hydrate (CSH) peak and decreases the intensity of the calcium hydroxide (CH) peak. The results showed that adding optimum percentages of nanosilica to cement-stabilized sandy soil enhances its mechanical and microstructure properties.

Effects of additional nanosilica of compressive strength on mortar

The use of nanosilica as one of the innovations in concrete technology has developed very rapidly. Some research mentioned that nanosilica obtained from the synthesis process silica sand is a type of material that is as pozolan when added to the concrete mix, so as to accelerate the hydration process in concrete. With the addition of nanosilica into the concrete mix, the compressive strength of the concrete can be increased and it has a high durability. This study aims to determine the effect from the addition of nanosilica on mechanical properties of concrete. Laboratory testing is conducted by making the mortar test specimen size of 50 mm x 50 mm x 50 mm. The material used is composed of silica sand, nanosilica, gravel, superplasticizer, cement, and water. Nanosilica percentage amount is added as much as 5, 10, and 15% by weight of cement. Testing of mechanical properties such as compressive strength mortar done at age 3, 7, 14, and 28 days. Based on the analysis and discussion obtained that at 28 days, mortar with the addition of 5% and 15% nanosilica has the compressive strength of 23 MPa. Addition nanosilika into the mortar to improve the mechanical properties by increasing the compressive strength of mortar. The compressive strength of mortar with the addition of 10% nanosilica is 19 MPa. The increase in compressive strength of mortar with the addition of 5% and 15% nano silica is 21% larger than the mortar with the addition of 10% nanosilica and without nanosilica. Nanosilica addition of more than 10% can cause agglomeration when mixed into the mortar so that the impact on the compressive strength of mortar.

Investigating the Performance Characteristics of Asphaltic Concrete Containing Nano-Silica

Using nano-technology materials in the asphalt pavement industry is new compared with Portland cement concrete. The main objective of this study is to investigate the effects of nano-silica modification on some properties of a penetration grade asphalt cement and a typical asphalt concrete. 60/70 penetration grade bitumen was modified with different percentages of nano-silica (i.e. 1, 3 and 5%, by weight) and was used for making the asphalt concrete specimens. After evaluating the basic properties of the modified binder, the asphalt concrete specimens were evaluated based on the stiffness and resistance against fatigue cracking, moisture damage and permanent deformation. The fatigue life of the modified mixtures was also calculated using an already developed regression model. The results showed that penetration grade and ductility increase and softening point decreases with increasing nano-silica content. Furthermore, results showed that the addition of nano-silica results in the increase of stiffness, tensile strength, resilient modulus, fatigue life and resistance against permanent deformation and moisture damage. The reduction of indirect tensile strength in wet the condition decreases with increasing nano-silica content. Dynamic creep test results showed that, the flow number of the control mixture and the mixture containing 1% of nano-silica is much lower than 10000 loading cycles. However, the mixtures containing 3 and 5% of nano-silica do not reach to the tertiary creep region after 10000 loading cycles.

Nano-Silica Effects on Mechanical Properties of Concretein Crude Oil Products Environment

This investigation develops some important data on the mechanical properties, bond strength between concrete and steel rebar and microstructure of crude Oil-Soaked Concrete containing silica fume and Nano silica. Experiments were performed in eight mixes with different percentages of Nano silica and different water-cement ratios. Concrete samples were cured in the petrol, gas-oil, 2.5% solution of sulfuric acid and water. To conclude, considering the results, recommendations on optimization of Nano silica, silica fume and water-cement ratio for this type of concrete for use in the construction of concrete tanks holding petroleum products are offered. The result shows that Nano silica can improves various properties of the concrete in corrosive conditions.