Colloidal Nanosilica Research Articles

Sustainable self compacting hybrid fiber reinforced concrete using waste materials

The current study investigates the behavior of hybrid fiber reinforced self compacting concrete (HyFRSCC) with crimped steel fibers (CSF) and polypropylene fibers (PPF) along with class F type fly ash (FA) and colloidal nano silica (CNS). To ascertain the fresh properties of self compacting concrete, the maximum volume of fiber content is restricted. The L16 orthogonal array of Taguchi method is followed to avoid the huge amount of experiments. In comparison to the control mix, mechanical properties of concrete are increased due to the combined effect of FA, CNS, CSF, and PPF. Rapid chloride penetration test is conducted to study the durability aspect of hardened concrete. Non‐destructive tests like ultrasonic pulse velocity and rebound hammer tests are conducted for the characterization of the properties of concrete. Based on the present study, a combination of FA, CNS, CSF, and PPF is proposed for an optimal recommendation in producing a ready‐mix type of HyFRSCC.

Assessment of the influence of micro- and nano-silica on the behavior of self-compacting lightweight concrete using full factorial design

The effects of different replacement levels of micro-silica (MS), colloidal nano-silica (CS) and also the combined addition of MS and CS on the behavior of self-compacting lightweight concrete (SCLC) were studied using the general full factorial design method. Three factors, including water to binder ratio (w/b) with two levels of 0.35 and 0.45, CS with four replacement levels of 0, 1, 3 and 5%, and MS with two replacement levels of 0% and 10% were chosen and three tests were conducted for each response. The modulus of elasticity, compressive strength and water absorption were selected as the responses at the age of 28 days. Also, using multiple regression analysis, acceptable prediction regression models were derived. The analysis of variance (ANOVA) showed that the effects of all three factors on fresh and hardened properties of SCLCs were significant. The results displayed that the mentioned properties for the SCLC specimens containing MS or CS improved, but the best performance was obtained in ternary mixes which were created by adding both MS and CS simultaneously. The optimal condition for having the best result of SCLC was obtained when the amounts of MS and CS were 10% and 3%, respectively.

Synthesis of colloidal nanosilica from waste glass powder as a low cost precursor

Waste glass powder was used as a low cost precursor for production of colloidal nanosilica for the first time. The process includes production of wet silica gel and thermal peptization of the wet gel. Purification of the glass powder and wet gel production were initiated by acid washing. The obtained powder was reacted with sodium hydroxide to produce wet silica gel. Type of the applied acid was examined in one factor at a time route. Temperature of the alkaline step and concentrations of the applied acid and base were investigated using Taguchi design of experiments. After finding the best combination of the investigated factor levels in production of the wet gel, time of the stabilization in thermal peptization was studied. Characterizations of the wet gel and colloidal silica were performed by XRF, DLS, FESEM, TEM, FTIR and N2 sorption evaluation. Accordingly pure and stable colloidal nanosilica (98.50%) with average particle size of 21.9 nm was produced from the glass powder successfully. Specific surface area of the dried porous optimum sample was 83.63 m2/g.

Effects of colloidal nano-silica on fresh and hardened properties of self-compacting lightweight concrete

The aim of this study is to investigate the effects of different levels of colloidal nano-silica (CS) on fresh and hardened properties of self-compacting lightweight concrete (SCLC). For this purpose, two concrete series including 16 concrete mixes with two water to binder (w/b) ratios of 0.35 and 0.45 were considered. The percentage of CS that replaced cement were 0%, 1%, 3% and 5%. Also, mixtures containing 0% and 10% MS were considered. The fresh properties of SCLCs were observed in terms of slump flow diameter and time, J-ring diameter, V-funnel time and U-box tests. The hardened properties were determined through mechanical properties (compressive strength, splitting tensile strength, flexural strength) and non-destructive tests (electrical resistivity and ultrasonic pulse velocity). The results of this work indicate almost all SCLCs satisfied the requirements of EFNARC. The results of hardened properties indicate that combined addition of MS and CS in SCLC was better than adding just one of them. The higher mechanical properties were obtained by ternary mixes containing 10% MS and 3% CS at both w/b ratios of 0.35 and 0.45. Moreover, the improvement of electrical resistivity and ultrasonic pulse velocity in ternary mixes were better than the binary and control mixes.

APLIKASI PUPUK SI ORGANIK DENGAN PUPUK N,P,K DALAM MENINGKATKAN P DAN SI TANAH PADA INCEPTISOL JATINANAGOR TERHADAP RESPON TANAMAN HANJELI (Coix lacryma Jobi L.)

The objective of this research was to determine the effect of combinations of N, P, K and organic silica fertilizers In Soil P and Si and growth Of Job’s Tears (Coix Lacryma Jobi L.). This research began on May 2017 to October 2017. This research has been done in experimental of Faculty Agricultural, Padjadjaran University Jatinangor. The experiment was in Randomized Block Design (RCBD) consisting of ten treatments with three replications; (A) Control, (B) NPK standard, (C) NPK + ¼ Silica Emulsion, (D) NPK + ½ Silica Emulsion, (E) NPK + ¾ Silica Emulsion, (F) NPK + 1 Emulsion of Ash Silica , (G) NPK + ¼ Nano Colloidal Silica, (H) NPK + ½ Nano Colloidal Silica, (I) NPK + ¾ Nano Colloidal Silica, (J) NPK + 1 Nano Colloidal Silica. The results showed that there was effect of Si fertilizer on soil P and plant growth. Treatment (J) NPK + 1 Colloidal Nano Silica gives Hanjeli the highest yield 5 MST, 7 MST, 9 MST and 11 MST with plant height 3.58 cm, 10.58 cm, 17.17 cm and 18.00 cm

Preparation of novel film-forming armoured latexes using silica nanoparticles as a pickering emulsion stabiliser

HypothesisFilm-forming polymer latex particles of diameter <300 nm can be prepared in the complete absence of surfactants, stabilised in part by silica nanoparticles through a Pickering type emulsion polymerisation. Control of the silica wettability through modulation of reaction pH or by reaction of the nanoparticles with a hydrophobic silane results in silica-covered latex particles. ExperimentsThe oil-in-water polymerisation process used methyl methacrylate (MMA) and n-butyl acrylate (BA) as co-monomers, potassium persulphate (KPS) as an initiator and a commercially available colloidal nano-silica (Ludox®-TM40). It was found that pH control before polymerisation using methacrylic acid (MAA) facilitated the formation of armoured latexes, and mechanistic features of this process are discussed. An alternative, more robust protocol was developed whereby addition of vinyltriethoxysilane (VTES) to control wettability resulted in latexes completely armoured in colloidal nano-silica. The latexes were characterised using SEM, cryo-TEM and AFM imaging techniques. The mechanism behind the adsorption was investigated through surface pressure and contact angle measurements to understand the factors that influence this irreversible adsorption. FindingsResults indicate that nanoparticle attachment (but intriguingly not latex size) is dependent on particle wettability, providing new insight into the formation of nanoparticle-armoured latexes, along with opportunities for further development of diversely functionalized inorganic/organic polymer composite particles.

Effect of colloidal nanosilica on early-age compressive strength of oil well cement stone at low temperature

The compressive strength of cement stone rises slowly when cementing marine shallow section at low temperature, resulting in increased drilling cost and risk. This paper presents results of experimental study that was conducted to investigate the effect of low temperature on early-age compressive strength of cement stone admixed with colloidal nanosilica. The compressive strength of cement stones was measured after aging at 4 °C for 1, 3, and 7 days respectively. The hydration products of different aging cement stone were analyzed by X-ray diffraction and Fourier Transform infrared spectroscopy, and the microstructures were observed by scanning electron microscopy. In addition, the hydration exotherm of colloidal nanosilica modified cement slurry during hydration process was tested at 20 °C. The results indicated that the compressive strength of cement stone significantly improved by colloidal nanosilica. Interestingly, colloidal nanosilica retarded the initial hydration, and then promote the hydration process afterward. The mechanism of colloidal nanosilica to improve the compressive strength of cement stone was that colloidal nanosilica consumed calcium hydroxide to produce additional calcium silicate hydrate, filling large pores and cracks inside cement stone. More importantly, nanosilica particles provided nucleation sites of cement hydration and modified the internal structure of the hardened stone. The improvement of early-age compressive strength of oil well cement stone is beneficial to saving costs and reducing risk.

Micromechanical damage analysis and engineering performance of concrete with colloidal nano-silica and demolished concrete aggregates

In this study, different samples of concrete, containing natural and recycled coarse aggregates and different ratios of nano-silica, were delicately prepared to examine the micro-structure associated material behaviour, and to quantitatively characterize the fracture surfaces after fast dynamic fracture. The first specimen includes 100% of natural aggregates and for the second one, 100% of recycled coarse aggregates were used only. In the other specimens, 0.5%, 1% and 1.5% of nano-silica together with 100% of recycled coarse aggregates were used, respectively. A number of tests including compressive and flexural strength, non-destructive ultrasonic, impact and water penetration tests were conducted for all specimens. Furthermore, scanning electron microscopy (SEM), X-ray computed tomography coupled with image analysis and laser vertical interferometry were employed for the characterization of nano-silica and the impact damaged fracture surfaces of some mixtures. According to the results, recycled coarse aggregate weakened the mechanical properties of the natural coarse aggregate concrete and increased the water permeability. However, it has been demonstrated that this reduction can be mitigated by adding nano-silica into concrete, incorporating recycled coarse aggregate as confirmed by the quantitative X-ray spectroscopy micro-chemical analysis. In addition, it was also concluded from the fractographical surface analysis that nano-silica reduces the pore amount and produces the concrete less porous at the macroscopic level. This, in turn, may stimulate toughening mechanism and crack deflection, leading to low micro-roughness number but high impact resistance during the fast dynamic fracture event.

Developing green cement paste using binary and ternary cementitious blends of low pozzolanic sewage sludge ash and colloidal nanosilica (short-term properties)

This study investigates the effect of small dosages of nanosilica (0.5 and 1.5% of the total binder) on physical, mechanical, durability, and microstructural properties of green cement paste containing sewage sludge ash (SSA) with low pozzolanic activity. Experimental results revealed that hardened performances of cement pastes were reduced significantly by incorporating SSA particles at higher replacement ratios (> 10%), whereas mechanical and durability properties of cement paste specimens were improved by the addition of nanosilica both at early and moderate ages. According to the microstructural investigation, the activity of SSA particles in the presence of nanosilica can be improved.

Optimization of Design Mix Proportion for Saturated Water Absorption of High Performance Concrete

This study involves the optimization of design mix proportion for saturated water absorption of high performance concrete (HPC) by Taguchi Method. In the present investigation, saturated water absorption test on 25 HPC mixes specimens made with colloidal nano silica and copper slag as replacement of cement and fine aggregate respectively has been conducted at the age of 28 days and 90 days of water curing. The concrete mixes has been replaced by 1%, 1.5%, 2%, 2.5%, 3% of nano silica and copper slag of 10%, 20%, 30%, 40%, 50%. From Signal-to-Noise ratio, the optimal parametric combination for saturated water absorption has been obtained. The Analysis of Variance has been done on experimental data values. The percentage contribution of the factors towards saturated water absorption is identified. The nano silica contributes towards less water absorption in 28 days curing, while the Copper slag found to the major contributing factor for the cause after the 90 days tenure of water curing.

Study on effect of colloidal Nano silica blended con-crete under compression

Ternary Blended Concrete (TBC) with Nano-Silica (NS) is receiving special attention because of its ability to improve the performance of concrete as compared with the control concrete. The present investigation deals about the behavior of TBC produced, using Fly Ash (FA) and Alccofine (ALC) as a partial replacement for cement along with four different types of colloidal NS (CemSynXLP, CemSynXTX, CemSynXFX, CemSynXTXla) as additives. The compressive strength of M30 grade of TBC was tested after 7, 14 and 28 days of curing. From the study, it has been found that the TBC mix with 25% replacement for cement (FA at 15% and ALC at 10%) and with addition of 1% CemSynXTXla type of NS as an additive has achieved higher strength than all other types of TBC mixes.

Chloride Resistance of Nanoparticle Repaired Concrete Measured by Accelerated Tests

This paper describes results of experimental investigation of chloride ion penetration in concrete. Chloride concentration have been studied in accelerated conditions. Part of concrete samples were treated with colloidal nanosilica solution to increase their resistance to further chloride penetration. Measurement of chloride profiles was performed and compared on samples subjected to accelerated electrical migration tests lasting for a few days. The chloride ion profile in samples was determined in layers of 5 mm thickness up to a total profile thickness of 45 mm. The developed chloride concentrations reached values found after several years of exposure in natural conditions. It was found that the resistance to chloride penetration is substantially improved by nanosilica injection and the resistance to chloride penetration is increased by 60%.

Using Colloidal Nano Silica to Enhance the Performance of Cementitious Mortars

Nanomaterials have been widely used in the past few decades due to their proven capacity to enhance the mechanical properties of materials. While many studies have sought to improve the understanding of how nanomaterials affect the behavior of concrete, additional research is needed in order to achieve the full potential of the material, especially in the presence of supplementary cementitious materials. This study aims to investigate the mechanical properties of cement mortars incorporating both nano-silica (NS) and class F fly ash (FA). Furthermore, mercury intrusion porosimetry (MIP) was performed to study its effect on pore characteristics, and thermogravimetric analysis (TGA) was performed to measure the calcium hydroxide Ca(OH)2 content in the mixtures. It was found that using nano-silica enhances the compressive strength, reduces the total porosity and accelerates the pozzolanic reaction.

Hybrid fiber reinforced self compacting concrete with fly ash and colloidal nano silica: A systematic study

The current systematic study investigates properties of hybrid fiber reinforced self compacting concrete (HyFRSCC) with crimped steel fibers (CSF) and polypropylene fibers (PPF) along with class F fly ash (FA) and colloidal nano silica (CNS). Optimization of HyFRC mix is conducted using L16 Taguchi Orthogonal Array where additive has four levels. Combination of 10% FA, 0.4% CNS, 1.25% CSF and 0.167% PPF found to be optimal recommendation. Multiple linear regression analysis predicts equations of tensile strength as the function of cylinder compressive strength, for combination of FA, CNS, CSF and PPF. A good correlation between tested and predicted values is obtained.

Hybrid silane-treated glass fabric/epoxy composites: tensile properties by micromechanical approach

The effect of interface modification on the interfacial adhesion and tensile properties of glass fabric/epoxy composites was evaluated in two directions of 0° and +45°. Herein, the glass fabric surface was modified by colloidal nanosilica particles and by a new blend of silane-coupling agents including both reactive and non-reactive silanes. Composite samples with high strength and toughness were obtained. A simultaneous improvement of tensile strength and toughness was observed for an epoxy composite reinforced with a hybrid-sized glass fabric including silane mixture and nanosilica. In fact, the incorporation of colloidal silica into the hybrid sizing dramatically modified the fiber surface texture and created mechanical interlocking between the glass fabric and resin. The results were analyzed by the rule of mixtures (ROM), Halpin–Tsai (H–T), and Chamis equations. It was found that the ROM equations provided approximate upper bound values for all investigated composite samples. In the samples containing nanosilica, the shear and elastic moduli values calculated by the Chamis and ROM equations showed good agreement with those obtained from experiments. However, in other samples, the values calculated by the H–T equation showed a better agreement with the experimental data. The analysis of fracture surfaces indicated that both silane and nanosilica particles had influence on the mode of failures at the interface.

Chemical and mechanical characterization of ternary cement pastes containing metakaolin and nanosilica

This paper, for the first time, focuses on the characterization of the chemical and mechanical properties of ternary cement pastes with the addition of up to 18% of metakaolin and colloidal nanosilica. The paste containing 15% of metakaolin and 3% of nanosilica presented an increase of 44% on the compressive strength and a reduction of 66% on the average pore diameter at the age of 91 days, in comparison with the reference paste. Results obtained remark the high potential of ternary cement mixes produced with the combination of metakaolin and nanosilica for the production of high performance cementitious materials.

Strength, elastic and microstructural properties of SCCs’ with colloidal nano silica addition

One of the concerns regarding the elastic behavior of self-compacting concretes (SCC) is their lower stiffness tendency compared to conventional concretes (CC). Because of mixture design methods applied, SCC mixtures, in general, contains higher amounts of fine materials. The use of high volume of fine materials causes a decrease in the amount of total aggregates which have an important role on the strength and elastic properties of concretes. This paper discusses the results of an experimental study which investigated the strength, elastic and microstructural properties of SCC mixtures modified with different particle sizes of colloidal nano-SiO2 (CNS). CNS samples, having 35, 17, and 5 nm average particle size, were used with the aim of reducing the total fine material (fly ash) content in SCC designs. With the help of CNS, the amount of fly ash in reference SCC mixture design was gradually reduced and replaced with aggregates. The mixtures which fulfill desired fresh SCC properties were subjected to compressive tests at 28th and 120th days. Moduli of elasticity of concrete specimens were also measured. Results have shown that, although the use of CNS in reduced-fly ash content mixtures could not compensate the strength decrement, the stiffness of SCC mixtures containing CNS together with fly ash has been strikingly improved even the increase in total aggregate content is not noteworthy. Microscopic investigations has indicated the development of a dense C-S-H gel and interfacial transition zone.

Properties of hybrid cementitious composite with metakaolin, nanosilica and epoxy

The compressive strength and durability potentials of hybrid cementitious composites (HCC) that contain metakaolin (MK), produced in the laboratory using raw kaolin, nanosilica and epoxy resin was the main focus of this research study. The HCC specimens contain 10% metakaolin (MK), 1% colloidal nanosilica (CNS) and 1% epoxy resins and the specimens were examined for early ages of 7, 28, and 90days of exposure in both water and seawater. The durability properties investigated in this research study comprise of water absorption, intrinsic air permeability, chloride penetration and porosity. All tests were conducted to assess the influence of MK, CNS and epoxy on the compressive strength and the durability properties of the HCC specimens. The result showed that HCC specimens with 10% MK, 1% CNS was durable relative to all the properties. Nevertheless, the addition of both natural fibers (coconut and oil palm fruit bunch fibers) and synthetic fiber (bar chip fiber) has a slight negative impact on the durability properties of HCC specimens. Conclusively, the results showed that the menace of water, liquid and gas transportation by water absorption, capillary suction, porosity, chloride penetration, and intrinsic air permeability of HCC were lesser than that of control specimen.

Effects of fly ash fineness, nano silica, and curing types on mechanical and durability properties of fly ash mortars

The effects of nano silica (NS), three different fly ash contents, two curing types and exposure to sulfate solution on mechanical and durability properties of two types of fly ash mortars are evaluated in this study. Results show that the wet‐cured mortars containing finer fly ash exhibited higher compressive strength at all ages than that containing coarser fly ash. The addition of colloidal NS improved the compressive strength of both types of fly ash mortars at all ages with significant improvement at early ages. The effect of steam curing slightly improved the 3‐day compressive strength of control cement mortar and both fly ash mortars with reduction starts from 7 days onwards. However, the addition of NS improved the compressive strengths at all ages of all fly ash concretes subjected to steam curing. The exposure to sulfate solution adversely affected the compressive strength at all ages of all fly ash concretes irrespective of fly ash contents, fineness types, and NS addition. Fly ash mortars containing finer fly ash exhibited slightly higher drying shrinkages but lower rate of water sorption than the mortars containing coarser fly ash. The addition of NS significantly increased the drying shrinkage and decreased the rate of water sorption of both types of fly ash mortars containing all fly ash contents.

Optimization of colloidal nanosilica production from expanded perlite using Taguchi design of experiments

Abstract Colloidal nanosilica was prepared from perlite in two stages: production of wet gel and thermal peptization. The influence of acidic and alkaline solutions concentration, temperature and pH of the gel were investigated in wet gel production using Taguchi design of experiments. Effect of the temperature of the peptization process was studied by full factorial design. The purity of the obtained silica gel was analyzed using X-ray fluorescence (XRF) and the colloidal silica was characterized by dynamic laser scattering (DLS), field emission scanning electron microscope (FESEM) and N2 sorption analyses. Results showed that pure colloidal nanosilica with purity of 99% was produced and the particle size of the product was in the range of 8 nm and 74 nm. Specific surface area of dried optimized mesoporous sample was 74.28 m2/g.