Nano SiO2 Research Articles

Insight into the Mechanical Properties and Microstructure of Recycled Aggregate Concrete Containing Carbon Fibers and Nano-SiO2.

This study aimed to improve the mechanical properties and microstructure of recycled aggregate concrete (RAC) by incorporating carbon fibers (CFs) and nano-SiO2 (NS) to promote the optimal utilization of RAC. The mechanical properties of the RAC were enhanced by both single and hybrid additions of CFs and NS, and the hybrid addition had a better strengthening effect. From the experimental results, it was found that the addition of CFs could increase the 28 d compressive strength and splitting strength of the RAC by 9.05% and 22.36%, respectively. The hybrid CFs and NS were more conducive to improving the mechanical properties of the RAC, and the enhancement effect increased first and then decreased with an increase in the NS content. The optimal content of NS was 0.8 wt%, which increased the 28 d compressive strength and splitting strength of the RAC by 20.51% and 14.53%, respectively. The microstructure results indicated that the addition of CFs had little effect on the optimized pore structure of the RAC, but the crack inhibition action of the CFs could improve the mechanical properties of the RAC. The addition of NS reduced the content of CH and facilitated the formation of more (C-S-H) gel. The hydrated calcium silicate (C-S-H) gel significantly decreased the porosity and transformed harmful capillary pores and harmful pores into harmless capillary pores and gel pores, thus improving the mechanical properties of the RAC. Therefore, the use of hybrid CFs and NS was more conducive to enhancing the performance of RAC for building materials.

Effect of nano‐SiO2 dispersion on the mechanical properties and frost resistance of modified cement paste

AbstractThe dispersion of nano‐SiO2 (NS) in cement plays a critical role in enhancing the properties of cementitious materials. In this study, the combination of ultrasonic dispersion and polycarboxylic acid water reducing agent (PCE) was used to significantly improve the dispersion of NS. The effects of ultrasonic dispersion time, NS content, and PCE content on dispersion quality were investigated, alongside their impact on mechanical properties, electrical resistivity, and frost resistance. The results demonstrated that this synergistic method optimized the dispersion of NS, leading to superior mechanical properties and frost resistance. With an ultrasonic dispersion time of 40 min, NS content of 1.0 wt.%, and PCE content of 0.75 wt.%, the cement paste achieved its optimal performance. Compared to non‐dispersed samples, compressive strength increased by 33.7%. After 75 freeze–thaw cycles, the mass loss was 2%, the relative dynamic elastic modulus was 99.15%, and the strength loss was 13.74%.

Hardening properties, water resistance and associated micro-mechanism of nano-modified calcium sulphoaluminate cement

Calcium sulphoaluminate cement (CSA) is considered a sustainable alternative to traditional Portland cement to reduce CO2 emissions. To further improve the hardening properties and water resistance of CSA and advance its extensive special engineering application, nanoparticles including nano-SiO2 (NS), nano-MgO (NM) and nano-Al2O3 (NA) were used as nano-modifiers for CSA. The effects of nanoparticles dosage on the setting time, compressive strength and water resistance of nano-modified CSA were experimentally evaluated, and the micro-mechanisms were also clarified by conducting X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TG) tests. The results showed that incorporating nanoparticles into CSA obviously shortened the initial and final setting times. The appropriate addition of nanoparticles effectively enhanced the compressive strength of CSA, and the optimum dosages of NS, NM, and NA were respectively determined to be 0.5 %, 1.0 %, and 0.5 %. Water immersion decreased the bonding strength of CSA, and adding nanoparticles can effectively weaken this water-induced deterioration effect. Under water immersion environment, the optimum dosages of nanoparticles would be increased to obtain the highest residual water immersion strength and minimum strength loss rate. The generation of ettringite was mainly responsible for the compressive strength and water resistance improvements of nano-modified CSA. The hydration process of nano-modified CSA was clarified and the corresponding micro-mechanism model was proposed. Furthermore, the benefits and challenges of using nano-modified CSA were also analyzed, advancing its widespread application in rapid repair of special engineering.

Enhancing the resilience of cement mortar: Investigating Nano-SiO2 size and hybrid fiber effects on sulfuric acid resistance

This article explores fortifying cement mortars against severe sulfuric acid (SLA) attacks by studying the impact of nano-SiO2 (NS), macro-steel (ST), and micro-polypropylene (PP) fibers. The aim is to assess their effects on workability, physical attributes, mechanical properties, and durability against SLA attacks when incorporated into mortar blends. Replacing 1 % of cement weight with NS, having average particle diameters of 15 nm (nm) (NS15) and 55 nm (NS55), and utilizing macro-ST and micro-PP fibers at volumes of 0.5 % and 1 % in singular and hybrid forms resulted in significant changes in mortar characteristics. While these additives increased fresh mortar viscosity and negatively affected workability, they substantially boosted mortar strength and durability against SLA attacks. The most substantial improvements were observed using smaller NS particle sizes and employing hybrid ST/PP fibers. The formation of calcium-silicate-hydrate (C-S-H) bonds by NS within the network emerged as a pivotal factor. NS's high pozzolanic activity and void-filling capacity significantly enhanced the mortars' strength and durability against SLA attacks. Furthermore, instead of their singular application, the combined use of ST and PP fibers proved more effective in restraining micro and macro cracks within the mortar matrix. The bridging effect of hybrid ST/PP fibers delayed crack propagation throughout the network, highlighting their superior efficiency against SLA attacks.Overall, these findings hold promise for designing cement-based composites resilient to harsh, acidic environments. Using smaller NS particles and hybrid fiber combinations presents potential pathways to prolong service life in challenging conditions.

Investigate growth of Paris polyphylla under synergic effects of CeO2 and SiO2 using as fertilizers

This study successfully synthesized SiO2 and CeO2 nano-materials to fertilize for Paris polyphylla (P. polyphylla). The obtained results indicated that nano CeO2 and SiO2 enhanced root growth and plan height of the P. polyphylla, respectively. This was due to the P. polyphylla absorbed SiO2 nano particles via roots and transferred them to the epidermis walls and vascular bundle of stem and leaves to protect as well as to induce growth of aboveground parts while the P. polyphylla also absorbed CeO2 nanoparticles and retained them in the epidermal roots to provide a medium culture accelerating the nutrient uptake of roots to significantly improve its growth. The simultaneously use of nano CeO2 and SiO2 greatly induced both root growth and plan height of the P. polyphylla. The extraction experiments suggested that significant amounts of gracillin, an important medicinal compound, accumulated in the P. polyphylla rhizome. Gracillin content in the rhizome of the CeO2 fertilized P. polyphylla was also greatly higher than that in the SiO2 fertilized P. polyphylla. Thus, the nano CeO2 not only promoted the development but also enhanced formation of gracillin in the rhizome of the P. polyphylla.

Study on the enhancement of flexible zinc-air battery performance with polyethylene glycol and nano SiO2 composite hydrogel

Flexible zinc-air batteries have garnered significant attention due to their high energy density, low cost, and environmental friendliness. However, issues such as poor cycle life and anode dendrite growth severely hinder their practical application. This study introduces polyethylene glycol (PEG) as a pore-forming agent and incorporates nano SiO2 into a polyacrylamide/carboxymethyl cellulose (PAM/CMC) composite hydrogel, resulting in a PAM/CMC/PEG/SiO2 (PCPS) composite hydrogel. Phase analysis and electrochemical characterization of PCPS were conducted. The hydrogel electrolyte formed in an alkaline KI environment, when assembled into a battery, achieved a capacity of 494.6 mAh/g and maintained a low potential range of 0.36 V for over 40 h, with an energy efficiency of 86.3 % for the first 60 cycles. To address the issue of dendrite growth in alkaline environments, this study also explores the performance of PCPS composite hydrogel in near-neutral environments.

Development and mechanical properties of nano SiO2 modified photosensitive resin for high-strength and high-brittleness 3D printing in rock reconstruction

3D printing technology, as a rapid prototyping method, can accurately reconstruct the internal structural characteristics of samples, making it highly promising for rock engineering applications. However, current 3D printing materials used to reconstruct rocks suffer from low strength and high ductility, which is inconsistent with the high strength and brittleness of natural rocks. This paper explores the use of silane coupling agents KH550 (γ-aminopropyl triethoxysilane) and KH570 (γ-methacryloxypropyl trimethoxysilane) to modify nano SiO2 powder. Through sample preparation and uniaxial compression tests, the mechanical properties and failure characteristics of the modified nano SiO2 powder were analyzed. The results indicate that, using the preparation method with a mass ratio of E-44 epoxy resin, KH550 modified nano SiO2 powder, and 593 curing agent at 80:40:26, the samples achieved an uniaxial compressive strength of up to 30.55 MPa without enhanced brittle post-processing. The failure characteristics exhibited significant axial tensile damage. Additionally, combining CT scanning technology demonstrated that the structural and mechanical properties of the samples can be effectively reproduced. Therefore, the 3D printing materials discussed in this paper provide a viable reference for accurately reconstructing high-strength and high-brittleness rock masses.

Enhancing anti-carbonation properties of oil well cement slurry through nanoparticle and cellulose fiber synergy

The anti-carbonation property of oil well cement (OWC) is critical for sealing efficiency of wellbores under geological CO2 sequestration. However, gas migration through OWC around wellbores may lead to a deterioration and failure of the entire storage system. Developing carbon-resistant cement has been the emerging trend in the research community. Previous studies mainly focused on nanoparticles alone to enhance performance of OWC, and the purpose of the research is to explore the synergy of nanoparticles and cellulose fiber (CF) in enhancing engineering properties (e.g., carbonation resistance) of oil well cement slurry. The focus was on investigating compressive strength, permeability, pore structure, and carbonation depth associated with the micro-level texture in a CO2 corrosion environment using X-ray diffraction, Scanning Electron Microscopy, and thermogravimetric analysis methods. Four nanoparticles, namely, nano-SiO2 (NS), nano-TiO2 (NT), nano-Al2O3 (NA), and nano-CaCO3 (NC), were selected for the mixture design. Results indicated that the incorporation of 1∼2 % NPs into the OWC paste resulted in a notable decrease in portlandite and an increase in calcium silicate hydrates, thereby enhancing compressive strength and hydration process. In addition, the single admixture of CF could minimize the formation of cracks in the cement matrix and reduce the average carbonation depth by 54 %. More importantly, the synergy of CF and NP significantly improved the resistance of OWC to carbonation, and the OWC mixed with CF and NS displayed the highest carbonation resistance.

Carbon fiber/nano SiO2 reinforced polyelectrolyte-graft UHMWPE for water lubricated superlubricity

In this study, a new kind of UHMWPE composite with ultralow coefficient of friction (COF) and high mechanical properties was developed. An efficient method was established to graft hydrophilic monomer 3-sulfopropyl methacrylate potassium salt (SPMK) onto UHMWPE powder by thermal initiation radical polymerization. The COF of UHMWPE grafted SPMK sample was significantly reduced by 50 %. After filling carbon fiber and nano SiO2, the COF of UHMWPE composites can be reduced as low as 0.009 at 0.1 m/s. Besides, a 76.1 % decrease in wear rate of single UHMWPE was achieved. The outstanding tribological properties of UHMWPE composite was attributed to the synergistic effect of hydration lubrication and particle reinforcement. The prepared UHMWPE composite has great potential to realize water lubricated bearing.

Facile and efficient superhydrophobic film for radiative daytime cooling

Abstract Facile and efficient radiative daytime cooling technology is still a huge challenge. In this paper, we proposed an eco-friendly, facile, efficient superhydrophobic radiative daytime cooling film composed of polydimethylsiloxane, nano TiO2, and nano SiO2. This radiative daytime cooling film could have about 15°C cooling of Al sheet, 9°C cooling for the building model on a sunny summer day, and 8°C cooling for the building model on a cloudy summer day, respectively. This method is promising to be used in building cooling fields.

Effect of nanoparticles reinforcement of silicon dioxide derived from prosopis juliflora on Silver-Grey magnesium nanocomposite: utilization of silicon dioxide mechanical and tribological properties

Abstract The automotive and aviation industries require lightweight materials to enhance working efficiency. Composites combine materials such as aluminium, magnesium, titanium, steel, and copper with various forms of reinforcements to offer lightweight alternatives for a range of applications. The present investigation aims to fabricate a Silver-Grey Magnesium (Mg-25%Si) alloy-based nanocomposite with silicon dioxide (SiO2) nano reinforcement at weight % of 0, 3.25, 6.5 and 9.75 utilizing the two step stir casting method. Prosopis juliflora is utilized in the production of different weight percentages of SiO2 nano reinforcements. The microhardness, tensile, wear, and impact tests are performed on the Silver-Grey Magnesium nanocomposites (Mg-25%Si/SiO2) utilizing a computerized tensometer testing machine, a Vicker’s hardness tester, a pin-on-disc tribometer, and an Izod impact, respectively. The x-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), and Energy-dispersive x-ray spectroscopy (EDAX) with elemental mapping microstructure were employed to scrutinize the tensile specimen fracture, EDAX, elemental mapping microstructure, wear, CoF, and worn surface characterization and impact strength analysis. When compared to the Silver-Grey Magnesium (Mg-25%Si) base alloy, the results of the Mg-25%Si/SiO2 nanocomposites demonstrated an increase in SiO2 nano reinforcements that significantly increased microhardness, tensile strength, wear resistance, and impact strength. The corresponding values are 113.36 VHN, yield and ultimate tensile strength of 603.25 MPa and 665.84 MPa, 0.00478 mm3 m−1, CoF of 0.38421 and 400 J m−1.

Comparing durability and compressive strength predictions of hyperoptimized random forests and artificial neural networks on a small dataset of concrete containing nano SiO2 and RHA

Through the increasing use of supplementary cementitious materials, the properties of concrete have taken on increased significance in a design code. Using reliable prediction models based on a small data set for the mechanical properties and durability of concrete can reduce the number of trial batches and experiments needed to produce useful design data in the laboratory, reducing time as well as resources. In this study, we investigate how the properties of water penetration, chlorine resistance, and compressive strength can be predicted by polynomial regression (PR), random forest (RF) regression, and artificial neural networks (ANNs) based on the input values of density, workability, and the constituent amount of rice husk ash, cement, and nano SiO 2 . We vary the training data used and test the coefficient of determination ( R 2 score) on the remaining data as a test set to measure predictive capability. We show that RFs and ANNs outperform PR in all settings and have unambiguously extrapolating properties when hyperparameter optimization is designed for this purpose. Remarkably, we obtain R 2 scores on the test data of 0.858 − 0.990 for RFs and 0.825 − 0.985 for ANNs.

Molecular dynamics simulations of the micro mechanism of functionalized SiO2 nanoparticles and carbon nanotubes modified epoxy resin adhesives

AbstractThe bonding interface of carbon‐fiber‐reinforced polymer (CFRP)‐reinforced steel structure is a weak part, and nanomaterial‐modified adhesives are expected to improve its comprehensive performance. This paper investigates the micro‐modification mechanisms of nanomaterials on epoxy resin adhesives using molecular dynamics simulation method. It explores how the functionalized nano SiO2 and carbon nanotubes affects the thermal and mechanical properties of the epoxy resin adhesive. The models established using Materials Studio software include the pure epoxy resin adhesive model (EP) with varying degrees of crosslinking, the functionalized nano‐SiO2‐modified epoxy resin adhesive model (EP + SiO2/OH), the single‐walled carbon nanotube‐modified epoxy resin adhesive model (EP + SWNT), and the synergistic enhancements model of the epoxy resin adhesive with nano‐SiO2 and carbon nanotubes (EP + SWNT + SiO2/OH). Based on the aforementioned models, the Forcite module is used to calculate the free volume, glass transition temperature and mechanical properties of the adhesive. The results show that the degree of crosslinking effects significantly the mechanical performance of epoxy resin adhesive. A high degree of crosslinking restricts the movement of the molecular chain, enhancing the strength of the epoxy resin adhesive. Furthermore, the trend of the mechanical and thermal properties of the four models remains constant with the rise of temperature, and the properties decrease most significantly in the range of the glass transition temperature. Moreover, the epoxy resin adhesive doped with nanomaterials exhibits varying degrees of enhancement in mechanical and thermal properties. The epoxy resin adhesive reinforced with functionalized nano‐SiO2 and carbon nanotubes exhibits better properties compared to those with a single nanomaterial.Highlights The micro‐modification mechanism is revealed for nanomaterial modified epoxy resin adhesive. The degree of crosslinking effects significantly the mechanical performance of epoxy resin adhesive. The epoxy resin adhesive doped with nanomaterials exhibits varying degrees of enhancement in mechanical and thermal properties.

Enhancing wheat tolerance to salinity using nanomaterials, proline, and biochar-inoculated with Bacillussubtilis

Salinity negatively impacts crop production by affecting physiological and biochemical processes in plants. This study investigates the effectiveness of Nano-ZnO (NZn), proline (PA), Nano-TiO2 (NTi), Nano-SiO2 (NSi)), and biochar inoculated with Bacillus subtilis (OSBS) in enhancing wheat tolerance to salinity stress. Pot experiments were conducted under saline conditions with varying rates of biochar and foliar applications. Results indicated that 2 % OSBS with NZn and NSi significantly improved wheat growth, leaf area, and nutrient level, reducing the negative impacts of salinity.

Freeze-thaw cycling of nano-SiO2-modified recycled aggregate in concretes: Hydro-thermal-mechanical modeling

The freeze-thaw cycling in the cold region causes severe damage to the concrete, which seriously affects the durability of concrete. In this paper, nano-SiO₂ (NS) modified RAC (NS-RAC) specimens were prepared by impregnating RCA with a 3 % NS dispersion for 48 h with following frost resistance assessed experimentally. To further fully understand the performance of NS-RAC under freeze-thaw (F-T) cycles, a comprehensive hydro-thermal-mechanical coupling model was established to simulate the damage behavior of NS-RAC under F-T conditions. A random polygon microstructure model of RAC was developed, and the characteristics of RCA and three types of ITZs were discussed. The damage control equation for RAC during the F-T process was defined based on the coupling effects of percolation, temperature, and stress in a porous medium. The F-T cycle tests show that the compressive strength of NS-RAC samples after 100 F-T cycles is 9.04 MPa higher than that of RAC. Numerical simulation results indicate that, compared to RAC without NS, the maximum pore pressure, crystallization pressure, and maximum principal stress of samples with 3 % NS after the first F-T cycle are reduced by 3.84 %, 4.36 %, and 2.26 %, respectively. During the F-T cycle, with increases in ITZ width, aggregate gradation range, RCA replacement rate, and temperature difference, the internal stress of NS-RAC specimens increased to varying degrees. This study provides insights into the F-T damage of RAC in severe cold regions and promotes the practical engineering application of RAC in such environments.

Antifungal and Antioxidant Properties of Some Artificial Antioxidants, Generally Recognized as Safe Compounds and Nano-Oxides

In this study, the usage potential of some artificial antioxidants, generally recognized as safe (GRAS) compounds and nano-oxides solutions in wood preservation industry, was investigated. For this purpose, antifungal and antioxidant properties of solutions were determined. Erythorbic acid, ethoxyquin, potassium disulfide, sodium ascorbate, sodium erythorbate and Enginerring and Nature Sciences Faculty (TBHQ) were selected as artificial antioxidants; dehydroacetic acid, sorbic acid and sodium benzoate were used as GRAS compounds and nano MgO, nano CeO, nano ZnO, nano SiO2 and TiO2 were investigated as nano-oxides in this study. Three different concentrations (0.5%, 1.0% and 1.5% ) were prepared, and anti-fungal test were carried out. The brown rot fungus Coniophora puteana (Schumach.) P. Karst. (BAM Ebw. 15) was used for the anti-fungal test. Then antioxidant activity of the solutions were determined. Iron (III) ion reducing antioxidant power method (FRAP) was used to determine the antioxidant activity of solutions. All solutions at 1.5% concentration completely inhibited the growth of C. puteana fungus. The antioxidant activity of solutions was sorted as artificial antioxidants>GRAS compounds>nano-oxides, respectively. It was concluded that the tested substances can be used as impregnating agents in wood preservation.

Development of a fast and low-cost aqueous based-extraction protocol for the simultaneous extraction and characterization of SiO2 and TiO2 (nano)particles in confectionary products

BackgroundThe determination of (nano)particulate content from food additives has been a long-standing concern for authorities since it is of vital importance for ensuring food safety, regulatory adherence, and transparent consumer information. Nonetheless, a critical step in these determinations is the refinement of a careful and quantitative extraction process for particles that may be found within complex matrices such as confectionery products. The development of new technologies and analysis methods for nanoparticles is ongoing. Whereas new technologies and analysis methods for nanoparticles are being developed, the extraction of (nano)particles of different nature has not been adequately addressed in the literature. ResultsA simple aqueous extraction procedure was found to be suitable for the simultaneous extraction of TiO2 and SiO2 (nano)particles from five confectionery products. Neither the extraction agents (water, lipase, pancreatin and Tris-HCl solutions) nor the methods (manual shaking, ultrasonic bath, ultrasonic probe and ultrafiltration) altered the size, morphology, or aggregation state of either type of particle, as revealed by the micrographs obtained by Transmission Electron Microscopy (TEM). Single-particle ICP-MS (spICP-MS) determined that the optimal conditions for extracting both types of particles involve manual shaking using water as the solvent. Furthermore, the use of enzymes seemed to hinder the determination of both types of particles by spICP-MS. (Nano)particles of TiO2 and SiO2 were detected in all the confectionaries, even though the E171 additive was only labeled in one of them. The average percentage of nanoparticulate TiO2 material in the evaluated products was 30 %, while no nanometer-sized particles of SiO2 were detected. SignificanceEnsuring food safety, regulatory compliance and transparent consumer information relies on getting reliable results that connect with the application of sample treatment procedures for detecting unaltered nanoparticles in food products. The presented research introduces an economical, swift, user-friendly, environmentally responsible, and harmonious extraction method for the concurrent analysis of TiO2 and SiO2 particles in confectionery samples. Furthermore, particles from additives not included in the labeling have been detected, characterized, and quantified in the confectionary products.

Cucurbit[7]uril-Modified Nano SiO2 for Efficient Separation of Crude Oil Emulsions: Properties and Demulsification Mechanism.

Demulsification of crude oil emulsion is an obvious problem in the whole of petroleum engineering, which needs to be dealt with urgently. In this paper, a supramolecular material Cucurbit[7]uril-SiO2 (CB-SiO2) synthesized with excellent demulsification efficiency (DE) on O/W emulsion was synthesized by a simple thermal synthesis method. The microscopic morphology and structure were investigated through modern characterization techniques. Furthermore, its stability, dynamic interfacial tension (IFT), and wettability (three-phase contact angle (CA)) were systematically investigated, and the demulsification efficiency of different conditions on crude oil emulsion was also investigated. Reassuringly, these results showed that when the temperature was 70 °C, the demulsification dosage was close to 600 mg/L and remained unchanged for 90 min; the demulsification efficiency is 2.2 times compared with the unmodified material, up to 93.63%. In addition, a plausible demulsification mechanism was proposed, which is that CB-SiO2 can adsorb and disrupt the oil-water interface, leading to oil-water separation and promoting demulsification. It is a promising demulsification material for the oil industry demulsification.

High-Efficiency High-Temperature-Resistant Nanosilica Viscosity Reducer for Extra-Heavy Oil Viscosity Reduction.

Due to the fact that more conventional heavy oil recovery methods (heating, emulsification, dilution, and other methods) have many shortcomings, they cannot meet the demand of heavy oil exploitation. Therefore, there is a need for new recovery methods. In this paper, the surface of nano SiO2 was modified with a silane coupling agent, KH-560, to prepare a nanoviscosity reducer (NRV), which has high-temperature resistance (300 °C), calcium and magnesium resistance (Ca2+ + Mg2+ > 900 mg/L) and high viscosity reduction rate (>99%). FTIR and SEM measurements showed that KH560 has been successfully connected to the surface of SiO2. The particle size distribution of NRV is mainly distributed in 50-80 nm, which matches the results of SEM. The experimental results showed that the viscosity reduction rates of 1 wt % NRV on M-1 heavy oil before and after aging were 99.73% and 99.71%, respectively. The viscosity reduction effect of 1% NRV on M-1 heavy oil and the bleeding rate of emulsion formation were investigated when the oil-water ratio ranged from 9:1 to 1:9. The results showed that when the oil-water ratio was between 7:3 and 1:9, the viscosity reduction rate was greater than 99%. Besides, the bleeding rate of emulsion increases with the decrease of the oil-water ratio. What's more, static and dynamic adsorption experiments showed that the adsorption capacity of 1 wt % NRV was 1.746 mg/g and 1.668 mg/g sand, respectively. The interfacial tension experiment showed that the interfacial tension (IFT) between 1 wt % NRV and M-1 heavy oil was 0.052 mN/m, and low interfacial tension was beneficial to displace the oil in the formation pores. At the same time, the displacement effect of NRV on M-1 heavy oil at different concentrations (0.5, 1.0, and 1.5 wt %) and temperatures (200, 250, and 300 °C) was investigated by core flooding experiments. The results showed that the recovery rate increases with the increase of NRV concentration, and 1 wt % NRV at 300 °C will improve the recovery rate of M-1 heavy oil by 27.3% compared to steam flooding. NRV could reduce the viscosity of crude oil, which provides technical guidelines for the exploitation of heavy oil and extra heavy oil.

Laboratory investigation on static and dynamic properties, durability, and microscopic structure of Nano-SiO2 and polypropylene fiber cemented soil under coupled seawater corrosion and cyclic loading

Cemented soils in coastal harbors are susceptible to adverse factors such as seawater corrosion and cyclic dynamic loading, which may consequently reduce their stability and durability. In recent years, Nano-SiO2(NS) has been widely used to enhance the mechanical properties of cemented soil. However, this enhancement may potentially lead to a reduction in ductility. Conversely, polypropylene fibers (PP) have attracted widespread attention for their potential to enhance the ductility of cemented soils, but their ability to improve the strength of cemented soils is limited. To address these issues, this study focused on utilizing five different nano-dosages combined with four different fiber dosages to enhance cemented soils. These enhanced soils were then subjected to curing periods of 7, 28, and 60 days in seawater environments. The study employed various tests including unconfined compressive strength tests (UCS), uniaxial cyclic loading tests, scanning electron microscopy tests (SEM), X-ray diffraction (XRD), and nuclear magnetic resonance (NMR) to investigate the potential impacts of these additives on durability, strength, corrosion resistance, and microstructure evolution. The results of the study indicate that seawater corrosion and cyclic loading contribute to a reduction in the stability of cemented soils. However, the addition of NS and PP effectively enhances the compressive strength and durability of these soils. The optimal combination ratio is achieved when the dosages of NS and PP are 3.6 % and 0.8 %, respectively. In this case, the growth rate of unconfined compressive strength of cemented soils surpasses the sum of each individual dosage, increasing by 137.7 %, 245.6 %, and 235.3 % after 7, 28, and 60 days of curing, respectively. Furthermore, the growth rate of PP on the compressive strength of cemented soils remains largely unaffected by seawater corrosion. The optimal composite dosage of cemented soils effectively mitigates the increase in porosity caused by seawater corrosion. C-S-H enhances the mechanical interlocking between hydration products and PP by encapsulating PP, reducing energy transfer losses in cemented soils, and increasing their dynamic modulus. The volcanic ash reaction and nucleation effect of NS further enhance this effect, and their combined use significantly improves the seawater corrosion resistance of cemented soils.