Nano Silica In Concrete Research Articles

Nano-modified recycled aggregates via vacuum impregnation: Towards stronger and durable recycled concrete

For the first time, this study aimed to enhance the quality of recycled aggregates (RAs) by employing nano-silica (NS) and the vacuum impregnation technique. Specifically, RAs experienced water immersion, ordinary and vacuum impregnation with 2 % NS slurry, and vacuum impregnation with 4 % NS slurry. Subsequently, these nano-modified RAs were incorporated into concrete mixes, and their strength and durability were assessed. Following this, an examination of the pore structures and properties of the interfacial transitional zones (ITZs) in recycled concrete was conducted. The results demonstrate that in contrast to ordinary pretreatment methods, concrete containing nano-modified recycled aggregates after vacuum impregnation exhibits better compressive strength (+18.39 %) and reduced chloride ion penetration (−17.90 %), which is attributable to a more compact pore structure and enhanced ITZs. The findings prove that vacuum impregnation significantly enhances the modification impact of NS on RAs when compared to conventional impregnation methods, owing to the reduced agglomeration effect of NS in concrete.

A review on partial substitution of nanosilica in concrete

Abstract One of the most popular and widely used cementitious nanoparticle materials is nanosilica (NNS). Although several researchers discuss how NNS affects the characteristics of concrete, knowledge is dispersed, making it difficult for the reader to assess the precise advantages of NNS. Therefore, a detailed review is required for the substitution of NNS in concrete. The present reviews collect the recently updated information on NNS as concrete ingredients. First, a summary of the manufacturing, physical, and chemical characteristics of NNS is provided. Second, the characteristics of fresh concrete are examined, including its effect on setting time, flowability, air content, and fresh density. Third, strength properties such as compressive, tensile, and flexure capacity are discussed. Finally, microstructure analyses such as scanning electronic microscopy and X-ray diffraction are discussed. The results show that NNS enhanced the mechanical and durability of concrete due to the pozzolanic reaction and microfilling voids but decreased the slump flow. The optimum dose is important for maximum performance. The typical optimum dose of NNS varies from 1 to 3% by weight of cement. This article also suggests future research directions to improve the performance of NNS-based concrete.

Mechanical Properties and Bond Behaviour of Polypropylene Fibers and Nano Silica in Concrete

Concrete has a substantial impact on the environment. As cement is the main ingredient, whose production generates a significant amount of CO2. A small amount of nanoparticles added to concrete can change the nano-structure of cementitious materials, resulting in high durability. This present work explains the effects of using nano-silica material and polypropylene fibres in the traditional concrete mix. The Nano silica contents of 2%, 3%, and 4 % by replacing cement and polypropylene fibre with 0.1%, 0.15%, and 0.2% of the volume of concrete were considered. Various properties of concrete, such as flexural tensile strength, compressive strength, and split tensile strength were determined. Pullout tests (IS 2770 part 1: 1967) were also conducted to study the effect of nano silica and polypropylene fibre on the bond strength of the reinforcement bars and compared them with normal concrete. The tests are carried out at the casting age of 28 days. It is concluded that the use of nano-material and polypropylene fibres has a minute change in their compressive strength. The Split tensile strength and flexural tensile strength get enhanced by a considerable amount. The results of the study showed that the presence of both nano silica and polypropylene fibre in optimal percentages can improve the mechanical properties as well as bond strength of reinforcement bars embedded in concrete.

Mechanical Properties and Bond Behaviour of Polypropylene Fibers and Nano Silica in Concrete

Concrete has a substantial impact on the environment. As cement is the main ingredient, whose production generates a significant amount of CO2. A small amount of nanoparticles added to concrete can change the nano-structure of cementitious materials, resulting in high durability. This present work explains the effects of using nano-silica material and polypropylene fibres in the traditional concrete mix. The Nano silica contents of 2%, 3%, and 4 % by replacing cement and polypropylene fibre with 0.1%, 0.15%, and 0.2% of the volume of concrete were considered. Various properties of concrete, such as flexural tensile strength, compressive strength, and split tensile strength were determined. Pullout tests (IS 2770 part 1: 1967) were also conducted to study the effect of nano silica and polypropylene fibre on the bond strength of the reinforcement bars and compared them with normal concrete. The tests are carried out at the casting age of 28 days. It is concluded that the use of nano-material and polypropylene fibres has a minute change in their compressive strength. The Split tensile strength and flexural tensile strength get enhanced by a considerable amount. The results of the study showed that the presence of both nano silica and polypropylene fibre in optimal percentages can improve the mechanical properties as well as bond strength of reinforcement bars embedded in concrete.

Impact of Nano-silica on the hydration, strength, durability, and microstructural properties of concrete: A state-of-the-art review

Concrete significantly impacts the atmosphere as its primary raw material, Portland cement, determines a considerable proportion of carbon dioxide in its production process. Improving the strength and durability properties of concrete buildings could decrease their influence on the atmosphere. Adding a small proportion of Nano-silica (NS) to concrete could change concrete’s configuration at the Nano level. Compared to other nano-materials, Nano-silica has riveted a lot of consideration due to its pozzolan reaction with calcium-hydroxide to make a gel of calcium-silicate-hydrate. Nano-silica can promote the adhesion between the concrete’s binder and aggregate by coupling and efficiently enhancing and densifying the concrete’s matrix. The present review article focuses on studying the influence of different types and proportions of nano-silica on the hydration, strength, durability, and microstructural characteristics of different cement-based concrete. This review article shows that around 2–4 % of Nano-silica in various types of concrete is suitable to improve the influence of NS on the physical, durability, and mechanical properties and densify concrete microstructure. Also, the present challenges that the concrete industry is facing in the commercial utilization of nano-silica in concrete are discussed in this review article. It is established that this review article will produce novel concepts to endorse the practical utilization of Nano-silica in the construction sector and offer some productive designs for similar research studies in the future.

Predicting parameters and sensitivity assessment of nano-silica-based fiber-reinforced concrete: a sustainable construction material

This study evaluates the compressive strength (C–S) of nano-silica-based fiber-reinforced concrete (NS-FRC) by using advanced machine learning (ML) individual and ensembled techniques. The employed advanced ML approaches used for the analysis are Support Vector Machine (SVM), Multi-Layer Perceptron (MLP) and eXtreme Gradient Boosting (XGB). Furthermore, the level of accuracy for the employed advanced algorithms is also evaluated by the k-fold cross-validation technique. Statistical checks, i.e., root mean square error (RMSE), mean absolute error (MAE) and mean absolute percent error (MAPE), are also applied to validate the performance of algorithms. Sensitivity analysis is also made to explore the influence of input parameters on the C–S of NS-FRC. Among all, the XGB technique is found most effective for an accurate C–S prediction of NS-FRC. In XGB model, the coefficient of determination (R2) is 0.95, which is comparatively more than that of SVM (0.90) and MLP (0.90). The MAE value of XGB algorithm is 3.3 MPa which is lower than that of SVM (4.8 MPa) and MLP (4.5 MPa). In addition, RMSE value is also less for XGB algorithm (3.8 MPa) as compared to that of SVM (5.5 MPa) and MLP (5.9 MPa). Furthermore, the employed XGB models exhibited highest R2 of 0.95 as compared to the models reported in the available literature. The sensitivity analysis revealed that the nano-silica influenced the C–S of NS-FRC by 7%. Moreover, discussion reveals that nano-silica in concrete can have several benefits, such as improved microstructure, enhanced strength, prolonged durability, reduced cement content, and less carbon emission.

High Strength Nano Silica Based Concrete

There is a substantial curiosity in academia, the investment community and among manufacturers about the exhilarating opportunities offered by nano materials. Although a lot of applications for nanotechnology remain hypothetical, construction is one area where numerous ‘here and now’ applications have already emerged. While existing use is restricted, the market is likely to approach more than 500 million dollars within ten years. Concrete is most likely exceptional in the construction field, that it is the distinct material exclusive to business and hence, is the recipient of a reasonable quantity of research and development capital from the construction industry. SiO2 (Silica) usually is an integral part of concrete in the normal mix. On the other hand, one of the innovations made by the study of concrete at nano scale level is that particle stuffing in concrete can be enhanced by means of adding nano silica (NS), which results in the densification of the micro and nano structure of cementitious composite resulting in enhanced mechanical properties. In this research paper, the result of a thorough investigational analysis on the utilization of NS in addition to cement so that the strength and quality of concrete can improve has been achieved. The effect of various proportions of NS in concrete has been premeditated to evaluate the properties of NS based hardened concrete according to the standard concrete. The obtained outcomes after testing indicate that the addition of NS together with concrete has improved the mechanical behavior of concrete. The NS blended high strength concrete (HSC) shows a better compressive strength (CS) of 66.00 N/mm2 (MPa) after standard twenty eight days, which is an exceptional development over standard concrete. Each and every mixture containing NS in various proportions gave enhanced outcomes in comparison with the standard predictable concrete. RH (Rebound Hammer), UPV (Ultrasonic Pulse Velocity), SEM (Scanning Electron Microscope) and TEM (Transmission Electron Microscope) examinations further authenticate the above results.

Influence of Incorporation of Colloidal Nano-Silica on Behaviour of Concrete

The current research work is based upon the experimental study of the effect of the use of nano-sized particles of colloidal nano-silica (NS) on various properties of concrete. The concrete mixes are designed by substituting cement with 0.75%, 1.5% and 3% of colloidal NS. The analysis of experimental outcomes of this investigation illustrates that the compressive and tensile strength is enhanced with the increasing NS (%). Moreover, increase in density and decline in volume of voids and water absorption have been found due to the introduction of NS in concrete. Increase in mechanical properties and improved non-destructive test results indicates the qualitative improvement in concrete owing to the incorporation of NS. However, the inclusion of NS has no substantial impact on modulus of elasticity of concrete.

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.

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.

Beneficial Use of Nano-Silica in Concrete: A Review

Beneficial Use of Nano-Silica in Concrete: A Review

Experimental Investigations on Nano Silica in Concrete

Experimental Investigations on Nano Silica in Concrete

Effect of mixing methods of nano silica on properties of recycled aggregate concrete

The effect of presoaking of recycled coarse aggregate (RCA) in nano silica (NS) solution on the properties of recycled aggregates concrete is compared with the direct mixing of NS in concrete. In this study, four series of concrete are considered. The first and second series are control series containing 100% natural coarse aggregate (NCA) and 100% RCA, respectively. The third and fourth series are similar to the second series in every aspect except that 2 wt% NS is added through direct mixing in concrete and presoaking of RCA in 2 wt% NS solution of 24 hr, respectively. Results show that the measured 28‐day compressive strength of recycled aggregate concrete containing presoaked RCA is higher than that containing direct mixing of NS in concrete. The volume of permeable voids, water sorptivity, and chloride ion penetration measured after 28 days curing is also reduced in recycled aggregate concrete containing presoaked RCA in NS solution than that containing direct mixing of NS in concrete. The total porosity of mortar adjacent to presoaked RCA is also found to be significantly lower than the same, where NS is mixed directly. The concentration of pores in the matrix adjacent to presoaked RCA is also shifted to medium capillary pores from the large capillary pores of matrix adjacent to RCA containing no NS. The volume of medium capillary pores reduced significantly in the matrix adjacent to presoaked RCA compared to the same, where NS is mixed directly. The scanning electron microscopic image analysis also supports this observation.

Production and Application of Olivine Nano-Silica in Concrete

The aim of this research was to produce nano silica by synthesis of nano silica through extraction and dissolution of ground olivine rock, and applied the nano silica in the design concrete mix. The producing process of amorphous silica used sulfuric acid as the dissolution reagent. The separation of ground olivine rock occurred when the rock was heated in a batch reactor containing sulfuric acid. The results showed that the optimum mole ratio of olivine- acid was 1: 8 wherein the weight ratio of the highest nano silica generated. The heating temperature and acid concentration influenced the mass of silica produced, that was at temperature of 90 °C and 3 M acid giving the highest yield of 44.90%. Characterization using Fourier Transform Infrared (FTIR ) concluded that amorphous silica at a wavenumber of 1089 cm-1 indicated the presence of siloxane, Si-O-Si, stretching bond. Characterization using Scanning Electron Microscope – Energy Dispersive Spectroscopy (SEM-EDS) showed the surface and the size of the silica particles. The average size of silica particles was between 1-10 μm due to the rapid aggregation of the growing particles of nano silica into microparticles, caused of the pH control was not fully achieved.

Application of Nano Silica in Concrete for Enhanced Resistance against Sulfate Attack

Durability of concrete structure is a critical issue especially in severe environment when the concrete structure is exposed to sulfate attack, such as shorelines. nanoSilica is high pozzolanic material which is used recently in concrete to improve its mechanical properties. However, the durability of concrete against sulfate attack containing nanoSilica (NS) has not been investigated completely. In this study, the effects of NS has been studied on compressive strength, sulfate attack and morphology characteristics. The results show that increasing of compressive strength in specimens with NS is significant in early ages. Resistance of concrete specimen against sulfate attack was measured in 5% sodium sulfate solution for expansion of prime specimens. After a period of 180 days the samples containing zero, 2, 4, 6 and 8% NS lost 3.51%, 2.4%, 2.23%, 1.13% and 1% of their weights compared to the initial weights, respectively. The results indicate that the concrete samples containing 8% NS show best performance in terms of resistance against sulfate attack.

Comparative Study of the Effects of Microsilica and Nanosilica in Concrete

It is well recognized that the use of mineral admixtures such as silica fume enhances the strength and durability of concrete. This research compares the effects of adding silica fume and nanosilica to concrete and provides a better understanding of the changes in the concrete nanostructure. Nanoindentation with scanning probe microscopy imaging was used to measure the local mechanical properties of cement pastes with 0% and 15% replacement of cement with silica fume. A reduction in the volume fraction of calcium hydroxide in a sample with silica fume provides evidence of pozzolanic reaction. Furthermore, replacing 15% cement by silica fume increased the volume fraction of the high-stiffness calcium silicate hydrate (C-S-H) by a small percentage that was comparable with the decrease in the volume fraction of calcium hydroxide. A parallel study of cement pastes with nanosilica showed that nanosilica significantly improves durability of concrete. This research provides insight into the effects of nanosilica on cement paste nanostructure and explains its effect on durability of concrete. The nanoindentation study showed that the volume fraction of the high-stiffness C-S-H gel increased significantly with addition of nanosilica. Nanoindentation results of cement paste samples with similar percentages of silica fume and nanosilica were compared. Samples with nanosilica had almost twice the amount of high-stiffness C-S-H as the samples with silica fume.