MATERIALS AND STRUCTURES
·
2019
·Vol. 53
·期 1
·1-12
·
IF 2.548
Liu Xin,Feng Pan,Shu Xin,Ran Qianping
The agglomeration of nano particles in cement systems remains a major challenge for their wide use in construction materials. A method of preparing highly dispersed nano-SiO 2 in cement paste is introduced in this paper, and the effects of modified nano-SiO 2 (SiO 2 @PCE) with a core–shell structure on cement hydration and microstructure development were investigated by isothermal calorimetry, quantitative X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and nanoindentation. The results show that well-dispersed nano-SiO 2 @PCE particles in a cement system can significantly accelerate cement hydration at an early age. The highly dispersed nano-SiO 2 @PCE particles refine the pore structure of the hardened cement paste. More specifically, the number of harmless and less-harmless pores is increased, whereas the number of harmful and more-harmful pores is reduced. In addition, the proportion of high-density C–S–H and low-density C–S–H in the hardened cement paste at an early age increases by 69% and decreases by 27%, respectively, with the addition of 1.5% nano-SiO 2 @PCE. Through the seeding effect, cement hydration is accelerated pronouncedly with the addition of highly dispersed SiO 2 @PCE nano particles. In addition, the stiffness of the paste is enhanced by the pozzolanic reaction between SiO 2 @PCE and portlandite.
研究领域:
材料科学
·
土木工程
✓ 已验证
产品关联
DOI
高影响因子
KEY ENGINEERING MATERIALS
·
2018
·
IF 0
Jing Ran Wang,Chang Ming Ke,Jin Hua Zhang,Xue Xin Liu
This research was studied the effect of 15 nm SiO2 on the hydration behavior, hydration process and microstructure of spinel-containing high alumina cement (HAC), which is from high titanium blast furnace slag via smelting reduction method of Ti-Si-Fe making process. The results showed that with the increase of nano-SiO2, the heat released rate of hydration and the maximum peak were decreased and advanced. Accumulation of hydration heat to release was considerably improved before 16h. Nano-SiO2 can promote the formation of hydration products or promote the hexagonal phases CaAl2O4·10H2O and Ca2Al2O5·8H2O change into cubic phase Ca3Al2O6·6H2O, which has the pozzolanic and filler effects, which The pore size distribution of the hydration products was enhanced by nano-SiO2. At the same time, the flexural and compressive strength was increased gradually.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
CONSTRUCTION AND BUILDING MATERIALS
·
2019
·
IF 4.046
Yamei Cai,Dongxing Xuan,Chi Sun Poon
Swelling caused by alkali-silica reaction (ASR) in concrete is a deleterious behavior due to reactions between alkaline pore solution and amorphous or metastable forms of silica in aggregates. Generally, mitigation by using pozzolanic materials is commonly adopted. This study compared the effectiveness of a highly-reactive nano-SiO 2 (NS) and a slowly-reactive waste glass powder (WGP) on mitigating ASR of cement mortars prepared with crushed glass cullet as aggregates. The experimental results showed that incorporating 2% NS or 10% WGP or a hybrid of the two in the mortar can decrease the ASR expansion. Using WGP resulted in larger reduction in the ASR expansion than using NS. Meanwhile, there was an improvement of strength from 7 d to 28 d for the mortar prepared with WGP. The composition of reaction products containing the ASR gel formed in a simulated ASR condition and the macro-/micro-structure of the tested mortars were further analyzed. It was found that the reaction products formed with high ratios of Na/Si and Ca/Si were favorable in mitigating the ASR expansion. For the specimen prepared with WGP, the increase in the ratio of Ca/Si would increase the stiffness of the ASR gel, and a higher Na/Si ratio would help reduce the osmotic pressure. The findings from this study would be useful for the selection of pozzolans to mitigate the ASR effect when using crushed glass cullet as aggregates in cement mortars.
研究领域:
材料科学
·
土木工程
✓ 已验证
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2025
·
IF 8
Wei Liu,Jiale Song,Hui Zhao,Zhaokuan Cui,Shuheng Zhang,Yu Qiao,Chenhong Cao,Weiguang Li
The superhydrophobic coating can effectively inhibit the intrusion and adhesion of water-corrosive media on the surface of concrete. However, the poor mechanical stability and expensive materials significantly restricts its application in concrete engineering. Thus, superhydrophobic nano-SiO 2 @silane/silicate coating are successfully prepared by simply spraying nano-SiO 2 @silane on the surface of mortar pretreated by silicate. The pretreated silicate can enable the surface of mortar to enhance flatness and compactness, offering an optimal substrate for spraying nano-SiO 2 @silane hydrolysate. Further, the low surface energy of silane and the micro-nanostructure formed by nano-SiO 2 synergistically make the composite coating possess excellent superhydrophobic properties, with a contact angle of 154° and a slide angle of 5°. Notably, compared with original mortar, the water absorption rate, water vapor transmission rate, and chloride ion penetration depth are reduced by 86.4 %, 67.3 % and 87.9 %, respectively, exhibiting outstanding impermeability. In addition, the coated mortar possesses excellent self-cleaning properties and resistance to rain erosion. Meanwhile, the coated mortar also exhibits excellent resistance to mechanical wear (>200 cycles of abrasions) and resistance to UV radiation (>100 h). Such outstanding comprehensive performance can guarantee concrete to long-term apply in outdoors. This work provides a simple, feasible, economical, and effective research idea for developing superhydrophobic coatings on concrete.
研究领域:
建筑材料学
·
表面工程学
✓ 已验证
产品关联
DOI
高影响因子
FOOD CHEMISTRY
·
2020
·
IF 6.306
Li Wang,Shuang Shao,Million Paulos Madebo,Yuanyuan Hou,Yonghua Zheng,Peng Jin
Effect of nano-SiO 2 packing on postharvest quality and antioxidant capacity of two different loquat cultivars (white-flesh ‘Qingzhong’ and red-flesh ‘Dawuxing’) were determined. Results showed that nano-SiO 2 packing significantly inhibited internal browning, retarded the decline of total soluble solids, titratable acidity, ascorbic acid content and extractable juice in both cultivars. Decay index of nano-SiO 2 packing in ‘Dawuxing’ and ‘Qingzhong’ was 53.25% and 42.84% lower than control after the day 12, respectively. Meanwhile, nano-SiO 2 packing enhanced the contents of individual phenolic compounds and soluble sugar compounds, induced higher superoxide dismutase and catalase activities, which contributed to improving 1,1-diphenyl-2-picrylhydrazyl and hydroxyl radical scavenging capacity. Furthermore, the contents of total soluble solids, ascorbic acid and soluble sugar were higher in ‘Qingzhong’ than those in ‘Dawuxing’, which dedicated to better quality. These results indicated that nano-SiO 2 packing was a promising approach in inhibiting decay, maintaining quality and expanding shelf life of loquats.
研究领域:
植物学
·
食品科学
·
园艺学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Xuewu Li,Shaomeng Du,Chenghu Ma,Tian Shi,Wei Qi,Hejie Yang
Improving the corrosion resistance of widely used Al alloys is important for expanding their industrial and marine applications. Structural fragility and preparation cost have always been key factors for restricting anticorrosive application of extensively-reported superhydrophobic surface. In order to try and fight that, combining with polyurethane (PU) adhesion agent, 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) was encapsulated around nano-SiO 2 ceramics for robust coating in place of conventional structure preparation strategy on Al alloy surface. Such low-cost one-step air-spraying SiO 2 @PFDTES@PU coating was prepared by 0.03 g nano-SiO 2 ceramics addition, 100 μL PFDTES and 0.25 g PU with the highest water contact angle of 168.34° ± 2.72°, a rolling angle of 4.02° ± 2.08°, and a propylene glycol oil contact angle of 156.52° ± 3.35°. FE-SEM, laser confocal microscopy, EDS and XPS were used to investigate micro-nano morphology and chemical composition of the coating. Meanwhile, the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements showed that as-prepared coating exhibited larger capacitive arc diameter, enhanced charge transfer resistance, larger |Z| 0.01Hz value, positive shifting E corr and significantly reduced I corr , thus demonstrating a significantly improved corrosion resistance. In addition, sandpaper friction experiment was used to evaluate the mechanical stability of the fabricated superhydrophobic coating. Ultimately, its resistance to solid/liquid contamination and self-cleaning ability were also systematically assessed. This work provides strong technical supports for industrial and marine applications for such low-cost, wear-resistant and anti-corrosion coating.
研究领域:
材料科学
·
表面工程
·
腐蚀防护
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF WUHAN UNIVERSITY OF TECHNOLOGY-MATERIALS SCIENCE EDITION
·
2018
·Vol. 33
·期 5
·1176-1185
·
IF 0.524
Lu Guosen,Deng Min,Mo Liwu
C3S pastes containing 0%, 5%, 10%, and 15% nano-SiO2 mixed with de-ionized water and alkali solutions were prepared. When C3S was completely hydrated, the pastes were ground into powders with a particle size less than 80 μm. Adsorption and desorption characteristics of alkali ions adsorbed by C 3 S-nano SiO 2 pastes mixed with de-ionized water immersed in alkali solutions and those in C 3 S-nano SiO 2 pastes mixed with alkali solutions, were investigated. Meawhile, the adsorption mechanisms of alkali ions were discussed. Results showed that the contents of alkali ions adsorbed by C 3 S-nano SiO 2 pastes mixed with de-ionized water increased with increasing substitution levels of nano-SiO 2 and/or the initial alkali concentrations. In C 3 S-nano SiO 2 pastes mixed with de-ionized water, each paste was characterized by having a fixed alkali-adsorption capacity that was essentially independent of alkali concentration. No obvious difference between the adsorption capacity of a given paste for K + and Na + was observed. Adsorption of alkali ions in the pastes is considered to be caused by surface force which is related to the BET specific surface area of the paste, and charge compensation of C-S-H gel, mainly by electrostatic interactions. In C 3 S-nano SiO 2 pastes mixed with alkali solutions, alkali ions may enter the structure of C-S-H gel to replace a part of Ca 2+ in the interlayer. This assumption is supported by the structural characterization of C-S-H gel using 29 Si MAS NMR.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
POLYMER SCIENCE SERIES B
·
2023
·Vol. 64
·期 6
·897-905
·
IF 1.2
Li Yang,Liu Jun,Mai Chongyang,Lv Chengcheng,Guo Yawen,Zhao Lielun,Jiang Yan,Zhang Hongwen
Abstract In this study, the macroinitiator poly(hexafluorobutyl methacrylate) (PHFBMA) was first prepared by atom transfer radical polymerization (ATRP) method, and then PHFBMA- b -PHEMA block copolymer was prepared by ATRP method using hydroxyethyl methacrylate (HEMA) as the monomer. After that, the amphiphilic diblock copolymer was used to construct a porous membrane using breath figures. Surface hydrophobicity is one of the important properties of materials. It is inspired by the principle of nepenthes predation, that the slippery liquid-infused porous surface (SLIPS) mimics the inner wall structure of the pitcher plant. In order to enhance the surface hydrophobicity of the fluoropolymer coating, the silicone oil infused on the ultra-slip surface is innovatively modified by nano-SiO 2 filling. When the content of polysiloxane is unchanged (10 mL for silicone oil and 0.5 g for polysiloxane), the modified silicone oil filled with 1.5 g of nano-SiO 2 owns the best modification effect at the film concentration of 37.5 mg/mL. The results show that the hydrophobic properties of the SLIPS are greatly improved compared with the porous film. The water contact angle of SLIPS is 160 o , the sliding angle of SLIPS is 7°. In addition, due to the presence of surface silicone oil, the SLIPS has good resistance to bacterial adhesion.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
DOI
高影响因子
Journal of Building Engineering
·
2022
·
IF 7.144
Dan Wang,Junjie Li,Lina Zhang,Congcong Jiang,Ping Yang,Xin Cheng
In recent years, due to superior performance of nano-SiO 2 , it is widely studied and applied in cement-based materials to improve mechanical properties and durability of the matrix. Nano-SiO 2 could be a potential surface-treatment agent, however, the activity of nano-SiO 2 determines surface modification effect. In this work, in order to obtain high activity nano-SiO 2 , three samples, with different sizes, surface hydroxyl groups , and viscosities , were synthesized via a so-gel method by adjusting the experimental parameters such as water dosage and reaction temperature. Water absorption rate and chloride ion penetration experiments were carried out to investigate ion/water transmission property of cement-based materials after surface treatment using nano-SiO 2 . S-20 sample dropped the water absorption rates by 28.8% and chloride penetration depths by 57.5%. The pozzolanic reaction and accelerating C 3 S hydration process were carried out to evaluate the activity of obtained nano-SiO 2 . The above results indicate S-20 sample shows the highest activity. The preparation method of high-activity nano-SiO 2 is provided to significantly improve surface quality of the cement paste matrix.
研究领域:
土木工程
·
材料科学
✓ 已验证
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2019
·
IF 4.046
Kai Luo,Jun Li,Zhongyuan Lu,Jun Jiang,Yunhui Niu
Natural hydraulic lime (NHL) containing both hydraulic and air-hardening contents is of an ideal alternative binder for mortars used in interior decoration, cultural relics repair and historic buildings maintenance. In this study, early hydration and hardening properties of NHL2 with nano-SiO 2 (NS) were researched. Hydration exothermic rate firstly decreased within 5 h of hydration and then increased after 5 h of hydration with the increase of NS, which could be attributed to the C 2 S hydration and the additional pozzolanic reaction between Ca(OH) 2 and NS. It is noted that the initial hydration of C 2 S would be restrained by the increase content of NS in NHL2 due to the delayed exothermic peak occurring time within 5 h of hydration. A decreased porosity of hardened NHL pastes with the increase of NS at each curing age were observed, which might be also caused by the pozzolanic reaction between Ca(OH) 2 and NS. Meanwhile, an increased capacity for the pores about 50 nm and decreased capacity for the pores about 1 μm with the increase of NS were also observed. In addition, mechanical level of NHL could be improved from NHL2 to NHL3.5 when more than 2% NS were added.
研究领域:
建筑材料学
·
材料科学
✓ 已验证
DOI
高影响因子
Polymers
·
2019
·Vol. 11
·期 2
·255
·
IF 3.164
Tao Xu,Qiangqiang Xiao,Jiayu Chen,Li Li,Xiongjun Yang,Lifang Liu,Wenhui Yuan,Bingjian Zhang,Huijun Wu
This study proposes to utilize modified Nano-SiO2/fluorinated polyacrylate emulsion that was synthesized with a semi-continuous starved seed emulsion polymerization to improve the hydrophobicity, thermal stability, and UV-Vis absorption of polyacrylate emulsion film. To verify the proposed method, a series inspection had been conducted to investigate the features of the emulsion film. The morphological analysis indicated that Nano-SiO2was surrounded by a silane molecule after modification, which can efficiently prevent silica nanoparticles from aggregating. Fourier transform infrared spectra confirmed that modified SiO2and dodecafluoroheptyl methacrylate (DFMA) were successfully introduced to the copolymer latex. The particle size of latex increased with the introduction of modified Nano-SiO2and DFMA. UV-Vis absorption spectra revealed that modified silicon nanoparticles can improve the ultraviolet shielding effect obviously. X-ray photoelectron spectroscopy illustrated that the film–air interface was richer in fluorine than film section and the glass side. The contact angle of modified Nano-SiO2/fluorinated polyacrylate emulsion containing 3 wt % DFMA was 112°, slightly lower than double that of polyacrylate emulsion, indicating composite emulsion films possess better hydrophobicity. These results suggest that introducing modified Nano-SiO2and fluorine into polyacrylate emulsion can significantly enhance the thermal stability of emulsion films.Keywords:polyacrylate emulsion;nano-SiO2;fluorine;ultraviolet shielding effect;hydrophobicity
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL POLLUTION
·
2017
·
IF 5.099
Junxing Huang,Chuanzhou Liang,Xu Zhang
The application of nanotechnology in agriculture, pesticide delivery and other related fields increases the occurrence of engineered nanoparticles (ENPs) in soil. Since ENPs have larger surface areas and normally a high adsorption capacity for organic pollutants, they are thought to influence the transport of pesticides in soils and thereafter influence the uptake and transformation of pesticides. The adsorption pattern of racemic-metalaxyl on agricultural soils including kinetics and isotherms changed in the presence of nano-SiO 2 . The adsorption of racemic-metalaxyl on agricultural soil was not enantioselective, in either the presence or the absence of SiO 2 . The adsorption of racemic-metalaxyl on SiO 2 decreased to some extent in soil-SiO 2 mixture, and the absolute decrease was dependent on soil properties. The decreased adsorption of metalaxyl on SiO 2 in soil-SiO 2 mixture arose from the competitive adsorption of soil-dissolved organic matter and the different dispersion and aggregation behaviors of SiO 2 in the presence of soil. Interactions between SiO 2 and soil particles also contributed to the decreased adsorption of metalaxyl on SiO 2 , and the interactions were analyzed by extended Derjaguin–Landau–Verwey–Overbeek theory. The results showed that the presence of nano-particles in soils could decrease the mobility of pesticides in soils and that this effect varied with different soil compositions.
研究领域:
环境科学
·
土壤学
✓ 已验证
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）