Papers by Keyword: Nanosilica

Abstract: The greening of cement industry has become a necessity and obligation in many countries and the Global Green Cement market is projected to grow at a Compound Annual Growth Rate of 9.9% in the 2024-2032 period. The race for more sustainable concretes includes a number of key strategies, such as the substitution of cement/clinker with other cementitious materials. In the current research a CEMI (complying with EN197-1:2011) based industrial mix of self-compacting concrete (SCC) is modified with an experimental mix based on CEMII/B-M(P-W-L)42.5N conforming to EN 197-1:2011. The experimental mix presents a dual reduction in CO2 footprint, since not only it is formulated with CEMII, instead of CEMI, but it also contains 320 kg of CEMII/m³ instead of 420 kg of CEMII/m³, by substituting the remaining mass of binder with emery powder. nanoparticles of silicon dioxide (nanosilica) and 12 mm polypropylene fibres were also added. The 7-day compressive strength reached 45 MPa and the 28-day strength reached 51 MPa, marginally lower than that of the industrial mix (60.3 MPa). The performance of nanosilica is discussed. Selected fresh properties in terms of density, slump-flow, air entrainment and strength testing, coupled with surface morphology observations with the use of stereo microscopy shed light into the potentials of such sustainable SCC mixes.

Abstract: This study evaluated the combined effect of recycled glass powder (RGP) and nanosilica on the fresh-state properties of concrete. Mixtures were prepared with partial cement replacements of 10%, 15%, and 20%, incorporating nanosilica at 1.5 % by cement weight. The control mixture (RGP-0) does not include nanosilica, allowing comparison with the additive-containing mixtures. Results showed that RGP-10 improved workability, achieving a slump of 22.6 cm compared to 7.0 cm for RGP-0, while RGP-15 and RGP-20 exhibited only slight reductions in fluidity. Air content decreased in RGP-10, RGP-15, and RGP-20, with values of 1.6 %, 1.9 %, and 1.7 %, respectively, compared to 2.3 % in RGP-0, indicating that the mixtures with RGP and nanosilica develop a denser matrix with reduced void formation. Additionally, nanosilica accelerated early hydration, raising the initial temperature by up to 3.5 °C in RGP-20 without affecting workability. These findings demonstrate that moderate cement replacement with RGP and nanosilica can produce more stable, homogeneous, and sustainable concretes, providing useful insights for designing mixtures with improved fresh state performance.

Abstract: In Lima, many concrete structures experience accelerated deterioration due to physical and chemical factors, limiting their durability. This study evaluates the effect of recycled glass powder (RGP) and a nanosilica additive (1.5 %) on concrete with f’c = 27.5 MPa (280 kg/cm²), focusing on optimizing its mechanical properties, durability, and economic feasibility. Mixtures with 10 %, 15 %, and 20 % cement replacement by RGP were prepared, assessing compressive, tensile, and flexural strength, as well as permeability and water absorption. The mixture with 10 % RGP (RGP-10) showed the best early age mechanical performance, increasing compressive strength by 39.1 %, tensile strength by 12.7 %, and flexural strength by 26.2 % compared to the concrete control. Mixtures with 15 % and 20 % RGP showed lower initial strength, although future gains are expected due to delayed pozzolanic reactions. Regarding durability, RGP-10 reduced permeability by 9.02 % and water absorption by 6.45 %, while RGP-15 and RGP-20 achieved even greater reductions, with permeability decreasing by 11.48 % and 9.84 %, and water absorption by 8.68 % and 10.56 %, respectively. Although the nanosilica additive increases the initial cost, its combination with RGP produces significant improvements in mechanical properties and durability, contributing to a reduction in maintenance related costs, resulting in a durable, sustainable, and economically viable material.

Abstract: Sugarcane represents a significant agricultural commodity extensively cultivated in tropical and subtropical regions globally. Following the industrial processing of sugarcane, a substantial quantity of the byproduct known as sugarcane bagasse (SCB) is generated. Due to the overwhelming production of this biomass, bagasse is often incinerated as a method of solid waste management, leading to environmental problems. To remediate poultry wastewater, agricultural residue was repurposed into a bagasse-based bio-adsorbent enhanced with nano-silica and zeolite clay. FTIR analysis indicated the existence of functional groups such as the O-H stretching, C=C stretching, C-H bending, and C-N stretching. SEM-EDX analysis demonstrated that the synthesized bio-adsorbent exhibits a microporous structure, which is beneficial for filtration applications, and consists of varying concentrations of oxygen, carbon, and silicon. Moreover, the composite achieved up to 100% Cd removal, 100% As removal, 54.76% Pb removal, and 40% Hg removal, while reducing coliform counts by 93.42–99.11%. Dissolved oxygen increased by as much as 60.19%, and total ammoniacal nitrogen decreased by up to 42.05%, demonstrating the material’s strong remediation potential. Furthermore, notable enhancements in the physicochemical properties of the poultry wastewater, including temperature and pH, were also documented. This research study elucidates a significant improvement in the treatment of wastewater through the utilization of agricultural by-products sugarcane bagasse, thereby demonstrating the effectiveness of nano-silica and zeolite integration in developing sustainable and efficient adsorbent materials for wastewater remediation.

Abstract: Concrete deterioration is a major concern for structural engineers, as it can weaken and damage structures, posing safety risks. One of the most effective ways to protect concrete from deterioration is to modify it with pozzolanic materials. Pozzolanic can react with calcium hydroxide (Ca (OH)₂) in concrete to form strong, durable cementitious compounds. So this research aims at enhancing the durability of concrete structures against aggressive media attacks. Nanosilica (NS) was used in concrete mix design with different addition percentages of 0, 1, 1.5, 2, and 2.5 by cement weight. The durability of hardened concrete specimens was investigated as follows: measuring water absorption and contact angle; and determining chloride permeability by ion exchange chromatography. Also, the resistivity of concrete against both 3% sulfuric acid and 5% sodium chloride solutions was estimated. Finally, the electrochemical impedance spectroscopy (EIS) was used to determine corrosion resistance of the reinforced concrete. The experimental results detected that NS has a significant mechanism for improving concrete performance as follows: water absorption of concrete modified with 2% NS (M4) decreased by 41% as compared to the control sample, and contact angle increased by 66%. Meanwhile, the chloride permeability decreased by 24%. Moreover, NS is mainly responsible for enhancing concrete durability against aggressive media attacks up to 2% by cement weight. As compared to the control concrete specimen, the durability of the M4 specimen increased by 39% against sulphate attack and by 42% against chloride attack. The study provided a good solution for the problem of concrete building deterioration, especially when it is exposed to aggressive environments. Key words: Concrete durability, pozzolanic materials, nanosilica.

Abstract: The purpose of the current investigation was to lower the CO₂ footprint of an industrial self-compacting concrete mix, which currently consists of CEMI 42.5R solely, without any natural pozzolanas or supplementary cementitious materials. The target compressive strength of the industrial mix needed to exceed 55 MPa at 28 days of curing. In the present study we attempted a 20% reduction of CEMI 42.5R (by total mass of solids) by adding 20% of limestone filler and subsequently added 1% of colloidal nanosilica, aiming (i) at leveraging strength loss due to the reduction of Portland cement, (ii) at providing early strength and (iii) at enhancing the microstructure. A water to binder ratio of 0.42 was selected and superplasticizers were added. Fresh properties were studied in terms of slump-flow test, density and 1-day strength. In addition, the 28 day compressive strength was also tested, meeting the mix design strength requirement. Interestingly, the slump flow was improved, indicating better packing effect, however the compressive strength of the control formulations was higher than that of the nanoenhanced formulation. Further insights are also provided.

Abstract: 3D printing is now being used in many different applications. This adoption of 3D printing in these applications is accelerated by the development of new materials such as high performance polymers and nanocomposites. In this study, a commercially-available stereolithographic (SLA) resin has been reinforced with 0%, 0.1%, 0.3% and 0.5% nanosilica powder. The resulting mixture has been 3D-printed using a stereolithography 3d printer. The 3D-printed composites have been post-cured in a UV chamber and the mechanical properties have been assessed under compressive loading using a universal testing machine (ASTM-D695). The results show that adding nanosilica powder to the resin would increase the compressive strength of the resin, and that the highest compressive strength could be observed when 0.1% nanosilica poweder was added to the resin.

Abstract: The use of Atomic Force Microscopy (AFM) to observe the microstructure of asphalt binder promises a better insight compared to other microscopy techniques. In this study, AFM was used to investigate the effect of nanosilica concentration and aging conditions on the microstructure of asphalt binders. Asphalt binder penetration grade of 60/70 was modified with nanosilica (NS) by varying its concentration ranging from 1% to 5% (with the increment of 1%). Nanosilica modified binder (NSMB) were aged using a pressure aging vessel (PAV). The microstructure of the NSMB before and after aging were characterized using tapping mode of the atomic force microscopy (AFM). The effect of nanosilica (NS) addition and PAV ageing on the phase distribution, size of ‘bee’ structure and surface roughness of the asphalt binder were investigated. Based on this study, it was found that the addition of NS into asphalt binder tended to increase the distribution of the catana phase, as well as increasing the size of the bee structure and surface roughness of the AFM image. Besides that, the after long-term ageing was applied, the number of the bee structure and distribution of catana and peri phase also increased. It can be concluded that the addition of NS and aging increased the overall surface stiffness of the bitumen and has made the material surface more solid-like.

Abstract: In this study, nanosilica for Enhanced Oil Recovey (EOR) has been successfully synthesized using geothermal waste. The method used is wet grinding method with deposition time variations to determine its effect on time deposition on particle size. Characterization using X-Ray Fluoroscene (XRF), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were also carried out to determine the characteristics of the material. Wettability of nanosilica then was confirmed by contact angle test. Based on the results, it was shown that the purified silica has silica content up to 98.85% with an amorphous phase. The results of Particle Size Analyzer (PSA) show that deposition time determines nanoparticles size. The longer time deposition, the smaller particles can be produced with the best result at 4 days deposition because it can produced the smallest particle at 71.5 nm. The morphology of nanosilica is granular that has been confirmed by SEM. Contact angle test reveals that nanosilica geothermal waste has ability to change wettability. Nanosilica can decrease contact angel of crude oil from 23,3^o to 13,9^o.

Abstract: Nanosilica from rice husk ash (RHA) has been synthesized by a simple heating method. The obtained nanosilica was characterized by several techniques such as x-ray diffractometer (XRD), Fourirer transform infrared (FTIR), scanning electron microscope (SEM), and simultaneous thermal analysis (STA). The products had white color indicating that there were no impurities such as carbon or other elements. The XRD showed that the obtained nanosilica exhibited the pattern of amorphous silica material. FTIR spectra confirmed Si-O-Si and Si-O bonds in the obtained nanosilica. SEM images displayed the agglomeration of nanosilica particles with the average diameter of about 12 nm. STA showed that acid treatment was needed to remove carbon or mettalic ellements from nanosilica during the heating process. These results were important in supporting the utilization of rice husk to convert into other more valuable products with a simple method.