Use Of Nanosilica Research Articles

Performance evaluation of nanosilica-modified asphalt binder

Continuous efforts are being made to enhance the performance of the pavements for which various modifiers and additives are being utilized. Lately, emphasis has been given to the use of sustainable materials to be used in pavement construction. The paper explores the use of nanosilica, which can be manufactured from industrial and agricultural wastes, as an asphalt modifier and evaluates its effect on high-temperature properties of VG-10 binder. The paper investigates the rutting potential of nanosilica-modified binders by using different rheological approaches. Nanosilica was used in three concentrations (0.5%, 1% and 3%). It was found that adding nanosilica to asphalt binder improves its rutting resistance. Results of all the rheological approaches showed that resistance to permanent deformation increases with the addition of nanosilica. Nanosilica-modified binders have high resistance to oxidative ageing. Nanosilica-modified binders exhibited good storage stability at high temperatures.

Development of Nano-SiO2 and Bentonite-Based Mortars for Corrosion Protection of Reinforcing Steel.

In this study, the use of nano-silica (nano-SiO2) and bentonite as mortar additives for combating reinforcement corrosion is reported. More specifically, these materials were used as additives in ordinary Portland cement (OPC)/fly ash blended mortars in different amounts. The effects of nano-silica and bentonite addition on compressive strength of mortars at different ages was tested. Accelerated corrosion testing was used to assess the corrosion resistance of reinforced mortar specimens containing different amounts of nano-silica and bentonite. It was found that the specimens containing nano-SiO2 not only had higher compressive strength, but also showed lower steel mass loss due to corrosion compared to reference specimens. However, this was accompanied by a small reduction in workability (for a constant water to binder ratio). Mortar mixtures with 4% of nano-silica were found to have optimal performance in terms of compressive strength and corrosion resistance. Control specimens (OPC/fly ash mortars without any additives) showed low early age strength and low corrosion resistance compared to specimens containing nano-SiO2 and bentonite. In addition, samples from selected mixtures were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Finally, the influence of Ca/Si ratio of the calcium silicate hydrate (C-S-H) in different specimens on the compressive strength is discussed. In general, the study showed that the addition of nano-silica (and to a lesser extent bentonite) can result in higher strength and corrosion resistance compared to control specimens. Furthermore, the addition of nano-SiO2 can be used to offset the negative effect of fly ash on early age strength development.

Impact of Mixing process on the physical and Rheological Characteristics of Asphalt Binder Modified with Nano- Silica Powder

In Iraq pavements materials are exposed to various distresses due to the adverse environmental conditions and heavy traffic. The improvement of performance of flexible pavements is necessary for decreasing these distresses. The objective of this research is to improve the mixing efficiency of nano-silica particles with asphalt binder. Two mixer type (mechanical and high shear), rotational speeds (2000, 4000 and 6000 rpm), and mixing period (30 and 60 minutes) were assessed. Three nano-silica per cent 2%, 4%, and 6% by weight of asphalt were added and the asphalt binder mixtures were prepared by heating at mixing temperature 140 °C. Furthermore, comparisons were made to assess the modified asphalt binder characteristics such as penetration value, softening point, temperature sensitivity (penetration index), ductility and rotational viscosity. Results showed that the use of nano silica as an additive was useful in improving the asphalt binder characteristics. Generally, has been found that the penetration value decreased and softening point increased, as well as the viscosity, were increased and the temperature sensitivity was developed. Additionally, high shear mixing was more useful especially to obtain a good dispersion of nano silica powder in asphalt binder and got a homogenous composite material.

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.

Performance of Dense Graded Asphaltic Concrete Using Nanosilica Modified Bitumen

Flexible pavements are constructed to last for its design life, therefore, a good and durable asphalt surface layer is required. However, flexible pavements using dense graded asphaltic concrete have some shortcomings such as prone to rutting when heavy loads are applied at high ambient temperatures. One of the ways to improve the performance of dense graded asphaltic concrete is to modify the bitumen using nanosilica. Among the properties of nanosilica that is advantageous to improve the bitumen is strong absorption, large surface area and excellent stability. The objective of this study is to investigate the use of nanosilica as a bitumen modifier to improve the moisture susceptibility and rutting resistance of dense graded asphaltic concrete. Bitumen PEN 60/70 was modified with nanosilica at 2% by weight of bitumen. The performance of the asphaltic concrete specimens was then evaluated in terms of its moisture susceptibility, resilient modulus and rutting resistance. The results obtained from the testing showed that the addition of nanosilica increased the resilient modulus value and reduced the rutting depth of dense asphaltic concrete mixes, while achieving the required moisture resistance. It concludes that the addition of nanosilica in the bitumen improved the performance of dense asphaltic concrete mix.

Comparing the Effect of Nanomaterial and Traditional Fillers on the Asphalt Mixture Properties

Several parameters affect asphalt mix performance against loading and environmental conditions. Minor changes in the filler amount or type can cause obvious changes in the asphalt mixture properties. Accordingly, in this research attempts have been made to optimally make asphalt mixture strong against loading and environmental conditions by changing the type, size and percentage of filler used in asphalt mixture. In this line, the effect of two types of cement and nano-silica fillers in two different percentages was investigated and compared as an alternative for part of the main filler in asphalt mixture samples made by two types of limestone and granite aggregate. Cement filler by 2% and 4% of the aggregate mass as the alternative for part of the main filler is added to stone materials before mixing with binder, but nano-silica filler by 2% and4 % of weight of the binder as the alternative for part of the main filler is added to binder and a modified and homogeneous binder is produced using a high speed mixer. In the following, considering the optimum binder content for each mixture, resilient modulus tests were conducted to determine the strength performance against loading and indirect tensile strength ratio was used to determine moisture sensitivity of asphalt mixtures. Results obtained from resilient modulus tests show that the use of nano-silica and cement has been capable of favorably improving the resilient modulus of samples containing these two types of fillers. The improvement of the resilient modulus of samples containing nano-silica is very significant. Additionally, the studies conducted based on the indirect tensile strength ratio show that both types of alternative fillers, especially cement has been capable of desirably improve the strength of asphalt mixtures against moisture damage.

Enhancing Properties of Clay Mortars Using Nano-Additives

Earthen materials have been used in construction for centuries. Nowadays, a certain appeal towards natural materials rose again due to the various benefits they hold. Besides being inexpensive and approachable, earthen construction offers a clear sustainable method of modern manufacturing. Since earthen materials present high absorption and relatively low compressive strength, the main purpose of this study was to enhance these abilities of clay-based mortars using nanoadditives. To achieve the mechanical and physical invigoration of the clay matrix two different compositions were fabricated by the use of nanoclay, nanosilica and nanoalumina. The addition of nanoclay (NC) at 5%w/w of binder, indicated a lower water absorption and an increase in mechanical properties, while the use of nanosilica and nanoalumina combined at 1.5% and 1% w/w of binder respectively, outline a less stable and compact structure.

Synthesis of daisy-shaped core–shell nanocomposites of chiral poly[(±)-2-(sec-butyl)aniline] in the solid state

A green and simple procedure is reported on the synthesis of a daisy-like core–shell nanocomposite of chiral poly[(±)-2-(sec-butyl)aniline]/nanosilica. This morphology is related to the use of nanosilica and a mechanism based on intermolecular interactions between particles of nanosilica and the polymer. The morphology of the samples and their coating were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), SEM-map and energy-dispersive X-ray spectroscopy (EDX). The outstanding feature of this study is that it presents the first report of an in situ formation of daisy-like morphology for polyaniline nanocomposites through one-pot route without using pre-functionalized nanosilica and any other template under the solid-state condition; while this polymer has displayed no specific morphology under most conditions. According to XPS and CHNS analysis, the nigraniline oxidation state was confirmed as well as fully doping of composites (around 75%) in contrast with partial doping of poly[(±)-2-(sec-butyl)aniline].HCl salt. The structure of nanosilica was studied by 29Si NMR. The sample showed a conductivity around 5.2 × 10−2 S/cm, consistent with the XPS results which revealed the doping level. In addition, the TLM measurement was applied to determine the contact resistance. In this study, a chiral conductive nanocomposite was prepared under a solid-state condition in compliance with the green chemistry principles. Moreover, it was found that the nanocomposite is in delocalized polaron structure using solid acid as a dopant. Additionally, from the industrial point of view, the processability has been improved due to the introduction of the 2-sec-butyl group within the polymer backbone.

Improvement of Early-Age Strength of High-Volume Siliceous Fly Ash Concrete with Nanosilica - A Review

Abstract High-volume fly ash concrete, which incorporates more than 50 % fly ash as a replacement of cement in concrete, is a breakthrough development in concrete technology. Many of its properties have been investigated through decades of research, and the results have been disseminated. However, the construction industry has never showed confidence in using high-volume fly ash concrete. This is primarily due to its slow rate of strength development at early ages, notwithstanding its promising engineering and environmental benefits. Attempts have been made earlier to improve the early strength of the high-volume fly ash concrete by mechanical grinding, chemical activation of fly ash, addition of supplementary cementitious materials like silica fume, blast furnace slag, and metakaolin, etc. Nanosilica is a recent entry to the family of supplementary cementitious materials and has exhibited a better performance in concrete than other supplementary cementitious materials. This review discusses the limitations of high-volume fly ash concrete, most widely attempted methods to improve its early-age strength, and progress made on the use of nanosilica in this regard. The article also underlines the need for further research on nanosilica-incorporated high-volume fly ash concrete for developing a structurally viable and practically possible high-volume fly ash concrete, which could be a sustainable solution for the construction industry in future.

Combined effect of nano-silica, super absorbent polymers, and synthetic fibres on plastic shrinkage cracking in concrete

This research attempts to further add onto the existing knowledge-base of the utilisation of nano-silica in concrete by understanding its influence on plastic shrinkage in concrete, a subject with hardly any specific literature available. The results of extensive experimentation reveal that the adoption of nano-silica in concrete mixes should be cautiously undertaken, as it behaves in such a way to cause acceleration of the mechanisms of plastic shrinkage. This research has further been done in tandem with the combined plastic shrinkage crack mitigation methods, such as the use of synthetic fibres and super absorbent polymers (SAP) in concrete. The combined use of nano silica with SAP can be effective in alleviating the associated plastic shrinkage cracking. Synthetic micro-fibres too are useful in lessening plastic shrinkage cracking in nano silica mixes, but are not as effective as SAP. The mechanism of acceleration of plastic shrinkage cracking by nano silica is attributed to the finer particles of the material, causing reduced bleeding amounts in mixes in which it is incorporated.

Use of nanosilica- or nanolime-additioned TEOS to consolidate cementitious materials in heritage structures: Physical and mechanical properties of mortars

Tetraethoxysilane or tetraethyl orthosilicate (TEOS), also known as ethyl silicate, traditionally applied to consolidate stone, has recently begun to be used on Portland cement mortars and concrete with promising results. TEOS not only fills the pores in the substrate, but reacts with the cement favouring the precipitation of new C-S-H gels that densify and strengthen the materials. This study explored the effectiveness of new TEOS-based treatments bearing nanosilica (NS) or nanolime (NC) and their compatibility with cement materials found in the built heritage, given the participation of the various products in the pozzolanic reactions that may induce additional C-S-H gel. The physical and hydric properties (mechanical strength, porosity, surface gloss and colour, water vapour permeability and low pressure water absorption) of a Portland cement mortar were determined before and after applying the consolidants. Ethyl silicate alone or in conjunction with nanolime (4:1) proved to most effectively raise material strength and improve water repellence while conserving the original colour and gloss.

Improving Polyaspartic Anti-Corrosion Coating Protective Properties with the use of Nano-silica

The purpose of this study was to investigate and develop a polyaspartic coating, using nano-silica modified with an amino group (NH2-) in order to enhance adhesion on metallic surfaces and increase the effectiveness of the coating protective action against corrosion. Seven samples of polyaspartic coating with different amounts of nano-silica were prepared and applied to low carbon steel plates. The results showed that only 2% of the nano-silica per total weight formulation gave excellent protective as well as physical properties to the coating. The unique result was non-agglomeration and compatibility of nano-particles with the other compounds in the formulation structure. Time dependant behaviour of the coatings was followed by the EIS, SEM and FTIR methods and by exposure in a salt spray chamber. The main advantage was superior mechanical and chemical resistance and durability of a single coat, the properties that reduce emission of VOC and overall cost of the coating application process.

The Effects of Steel Fiber and Nano-SiO2 on the Cyclic Flexural Behavior of Reinforced LWAC Beams

The dead load and consequently the burden imposed on the structures due to earthquake can be reduced using Lightweight Aggregate Concrete (LWAC). In this study the cyclic flexural performance of LWAC beams is experimentally investigated to assess the influence of nano-SiO2 and steel fibers on the reversal flexural behavior. Tests were carried out on the reinforced LWAC beams with dimensions of 150 × 200 × 1200 mm under alternative cycles of variable displacement amplitudes. The cyclic behavior of these members including hysteresis response, load bearing capacity, envelope curve, stiffness, energy dissipation capacity and crack pattern are discussed and compared. The results showed that the addition of steel fiber significantly enhanced maximum flexural strength, cumulative dissipated energy, post-cracking stiffness and damage tolerance ability of LWAC beam. Adding nano-silica alone had slight effect on improving the reversal cyclic flexural behavior of LWAC. Furthermore the use of nano-silica increased the effectiveness of steel fiber on enhancement the cyclic flexural performance, especially at higher levels of displacement.

Beneficial Use of Nano-Silica in Concrete: A Review

Beneficial Use of Nano-Silica in Concrete: A Review

Peculiarities of hydration of Portland cement with synthetic nano-silica

Abstract Application of nano-materials in cement products significantly, improves their properties. Of course, the effectiveness of the materials depends on their quantity and the way they are introduced into the system. So far, amongst nano-materials used in construction, the most preferred was nano-silica. This research investigated the effect of synthetic precipitated nano-silica on the cement hydration as well as, on the physical and mechanical properties of pastes and mortars. Obtained results showed that admixture of nano-silica enhanced flexural and compressive strength of cement after 2 and 28 days, however, only when admixture made up 0.5% and 1.0%. On the other hand, the use of nano-silica in the amount 2% had some limitations, due to its ability to agglomerate, which resulted in deterioration of the rheological and mechanical properties.

Aggregation Behavior of Nano-Silica in Polyvinyl Alcohol/Polyacrylamide Hydrogels Based on Dissipative Particle Dynamics.

Due to the aggregation behavior of nano-silica in aqueous solution, the use of nano-silica without surface modification for synthesizing hydrogels is still a challenging task. This paper presents our study on the use of dissipative particle dynamics simulations to discover the aggregation behavior of nano-silica in polyvinyl alcohol (PVA)/polyacrylamide (PAM) blended hydrogels. By simulations, we aimed at investigating the effects of such factors as nano-silica content, polymer component ratio, temperature and shear rate on the aggregation behavior of nano-silica in terms of the mesoscopic morphologies and the relative concentration distribution functions. Our results reveal that the dispersion of nano-silica is seen if the nano-silica content is increased to 1.5%, and the aggregation of nano-silica becomes noticeable in blended hydrogels with an increase in the nano-silica content. This finding agrees well with the experimental results obtained by means of scanning electron microscopy. Furthermore, it is also found that the dispersion of nano-silica becomes more uniform with an increase in PAM content, temperature and shear rate. These findings greatly enrich our understanding of the aggregation behavior of nano-silica in PVA/PAM blended hydrogels.

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.

Differences in the coronal proteome acquired by particles depositing in the lungs of asthmatic versus healthy humans

Most inhaled nanomedicines in development are for the treatment of lung disease, yet little is known about their interaction with the respiratory tract lining fluids (RTLFs). Here we combined the use of nano-silica, as a protein concentrator, with label-free snapshot proteomics (LC-MS/MS; key findings confirmed by ELISA) to generate a quantitative profile of the RTLF proteome and provided insight into the evolved corona; information that may be used in future to improve drug targeting to the lungs by inhaled medicines. The asthmatic coronal proteome displayed a reduced contribution of surfactant proteins (SP-A and B) and a higher contribution of α1-antitrypsin. Pathway analysis suggested that asthmatic RTLFs may also be deficient in proteins related to metal handling (e.g. lactoferrin). This study demonstrates how the composition of the corona acquired by inhaled nanoparticles is modified in asthma and suggests depressed mucosal immunity even in mild airway disease.

Performance of Portland cement pastes containing nano-silica and different types of silica

This work compares the influence of nano-silica with three different silica-based materials (quartz, ultrafine quartz, and silica fume) on hydration, rheology, porous structure, and compression strength in cement pastes with 2.5% cement replacement. Results of calorimetry showed that the inclusion of the silica fume and of nano-silica resulted in an acceleration of hydration of the pastes. In regard to quartz, no change in comparison to the reference was observed until a median particle size of 0.6µm was reached. The use of nano-silica and silica fume was responsible for refinement of the porous structure and for an increase in compressive strength of the paste in comparison to the reference, caused by their role on heterogeneous nucleation and pozzolanic reactivity. On the other hand, quartz and ultrafine quartz did not have a marked effect on these properties. The rheological properties were also found to improve with addition of the different silicas.

Thermal Properties of Cement Mortars Containing Waste Glass Aggregate and Nanosilica

In recent years utilization of solid waste in building materials has gathered spectacular attention. One material with potential applications, especially in cement-based composites, is waste glass. The aim of this study was to evaluate the possibility of manufacturing sustainable cement mortars with the use of nanosilica (NS) and brown soda-lime waste glass (WG) fine aggregate. The mechanical and thermal properties of cement mortars containing WG aggregate and nanosilica, were analyzed in terms of waste glass and nanosilica content. Ordinary fine aggregate (river sand) was replaced with WG fine aggregate at a ratio of 100% by weight. Moreover, 0, 1 and 3 wt% of NS was incorporated to cement mortar. The experiment revealed that the presence of WG fine aggregate significantly decreased the thermal conductivity of the cement mortars and that furthermore, the sorptivity coefficient decreased. The study has shown that WG fine aggregate can be a successful substitute for natural fine sand without leading to mechanical deterioration and by significantly improving thermal properties of cement mortars. Additionally, the incorporation of nanosilica (especially in higher contents – 3 wt%) leads to a further decrement in thermal conductivity and sorptivity and improves compressive strength.