Silane Emulsion Research Articles

Research and performance analysis of water-resistant phosphogypsum masonry materials

Phosphogypsum is a solid waste produced by the phosphoric acid industry. With the development of the phosphoric acid industry, the emissions of phosphogypsum are increasing year by year and its recycling rate is low. The environmental problems caused by tailings storage are becoming increasingly serious. The chemical formula of the main component of phosphogypsum is . its performance is similar to that of natural gypsum. Using phosphogypsum as a raw material to produce phosphorus building gypsum is one of the main ways to utilize phosphogypsum resources. However, phosphogypsum building materials have poor water resistance and low strength, which greatly limits their application. Based on the analysis of the poor resistance mechanism of phosphogypsum, this paper analyzed and studied the mechanical and water resistance properties of phosphorus building gypsum by separately adding different amounts of polyvinyl alcohol and silane emulsion and mixing polyvinyl alcohol and silane emulsion . The conclusion is that adding waterproofing agents and water-reducing agents can greatly improve the water resistance of phosphogypsum building materials.

Immobilized horseradish peroxidase on boric acid modified polyoxometalate molecularly imprinted polymer for biocatalytic degradation of phenol in wastewater: Optimized immobilization, degradation and toxicity assessment

The degradation of phenol from wastewater is crucial for environmental protection. Biological enzymes, such as horseradish peroxidase (HRP), have shown great potential in the degradation of phenol. In this research, we prepared a hollow CuO/Cu2O octahedron adsorbent with a carambola matrix shape through the hydrothermal method. The surface of the adsorbent was modified by silane emulsion self-assembly, where 3-aminophenyl boric acid (APBA) and polyoxometalate (PW9) were combined with silanization reagents and grafted onto the surface. The adsorbent was then molecularly imprinted with dopamine to obtain boric acid modified polyoxometalate molecularly imprinted polymer (Cu@B@PW9@MIPs). This adsorbent was used to immobilize HRP, which served as a biological enzyme catalyst from horseradish. The adsorbent was characterized, and its synthetic conditions, experimental conditions, selectivity, reproducibility, and reusability were evaluated. The maximum adsorption amount of HRP under optimized conditions was 159.1 mg g−1, as determined using high-performance liquid chromatography (HPLC). At pH 7.0, the immobilized enzyme showed a high efficiency of up to 90.0% in removing phenol, after 20 min of reaction with 25 mmol L−1 H2O2 and 0.20 mg mL−1 Cu@B@PW9@HRP. Growth tests of aquatic plants confirmed that the adsorbent reduced harm. Gas chromatography-mass spectrometry (GC-MS) tests revealed that the degraded phenol solution contained about fifteen phenol derivatives intermediates. This adsorbent has the potential to become a promising biological enzyme catalyst for dephenolization.

Stable construction of superhydrophobic surface on polypropylene membrane via atomic layer deposition for high salt solution desalination

A facile and effective strategy, integrating atomic layer deposition (ALD) with photo-deposition, is developed to fabricate uniform a superhydrophobic surface on the membrane for high salt solution desalination. More specifically, a titanium interlayer was prepared by accurately controlled ALD on polypropylene (PP) microporous membrane, then a superhydrophobic modification was constructed on titanium interlayer by covalent silica deposition with nano silane emulsion (NMES). The ALD can uniformly coat an ultrathin TiO2 nanoparticle layer on the PP membrane surface by chemical adsorption, and photo-deposition assembles a stable composite layer reacting with TiO2 nanoparticles. It shows that the contact angle of the PP/TiO2-NMES composite membrane is higher than 150°, which exhibited an excellent anti-wetting capacity in high salt (15 wt%) vacuum membrane distillation. Moreover, the chemically stable bonding between the superhydrophobic layer and the PP membrane made the composite membrane to demonstrate its stability in long-term scaling experiments. Our work provides a viable bottom-up synthesis scheme to tailer and optimizes the inorganic layer on the inert polymeric surface.

Polymer functional coatings modified by ZrP‐based composites: Preparation and applications on marine concrete

AbstractThe development of high‐performance coatings for concrete structures is essential to ensure their durability and service life. However, most of the proposed developed strategies suffer from various limitations, especially regarding the wear and biological‐corrosion resistances of the coatings. This work reports a facile and efficient method to prepare effective composite coatings by nano‐modification, in which the intercalated composites play structural and functional roles in the corrosion, wear, and biological‐corrosion resistances. An in situ assembly synthesis was used to prepare the intercalated composites. The composites exhibited an innovative alternating skateboard structure and a functional composition. The silane‐emulsion modified with the composites was prepared and coated on the mortar surface to systematically study its performance at the concrete interface. The results indicate the good dispersion stability of the innovative α‐ZrP composites in the silane emulsion and their significant enhancement of the silane coatings' ability to improve the durability of marine concrete. The mechanisms of performance improved by the prepared composites through their unique lamellar structure and interlamellar silver‐nanoparticle composition were also examined. The prepared composite coating exhibits a new strategic approach to solve problems associated with concrete applications and provides technical guidance for surface protection of marine concrete structures.

Water absorption behavior of hydrophobized concrete using silane emulsion as admixture

Influences of silane emulsion as hydrophobic agent on pore structure of hardened cement paste (hcp), compressive strength and water absorption behavior of concrete were studied through pore structure analysis, water contact angle test and water/isopropanol absorption measurement. Results indicate that silane slightly inhibits early cement hydration and slightly reduces the 28-d compressive strength of concretes. The incorporation of silane significantly decreases the water sorptivity of concretes ascribed to the hydrophobization of capillary walls in hcps, whereas isopropanol absorption is not visibly affected by the addition of silane. The absolute water sorptivity decreases along with increasing water absorption amount for each group of concrete, which is believed to originate from swelling of C-S-H gel upon water absorption. However, the relative water sorptivity of the silane-modified concretes to the plain concrete remains constant during water absorption. A predicting method for long-term water absorption behavior of the silane-modified concrete is proposed.

Efficacy and mechanism of graphene oxide modified silane emulsions on waterproof performance of foamed concrete

As a lightweight construction material, foamed concrete has garnered considerable attention due to a variety of advantages. However, the high-water absorption increases the burden on the structure and accelerates freeze-thaw damage, and thus reduce the durability of foamed concrete. Herein, two kinds of waterproofing materials based on isobutyl triethoxysilane (IBTS) emulsion and graphene oxide/silane (GO/IBTS) composite emulsion were synthesized and used for foamed concrete by facile coating and soaking method. The results show that the soaked specimens exhibit excellent waterproof performance and the water absorption is almost 0%. By contrast, an internal waterproof layer is occurred in the coated specimens, and the water absorption rates of foamed concrete coated with IBTS emulsion and GO/IBTS emulsion are reduced by 75% and 82%, respectively. The waterproofing mechanism of the silane emulsion were analyzed by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), flourier transform infrared (FT-IR), x-ray fluorescence analysis (XRF) and x-ray diffraction (XRD). The results demonstrate that the foamed concrete shows a rough surface topography and low surface energy after IBTS treatment, which resulted in a superhydrophobic surface. While the surface of foamed concrete became rougher with the admixture of GO, which further enhanced the waterproof performance of foamed concrete.

Investigation of composite silane emulsion modified by in-situ functionalized graphene oxide for cement-based materials

Silane coatings were ubiquitously utilized to protect the structure concrete against water and aggressive ions in marine environment. In this paper, a novel design method for silane-based nanocomposite is proposed to enhance the water repellence for silane coatings. The graphene oxide sheets (GO) were first functionalized by in-situ polymerization of dopamine (DA), and then isobutyltriethoxysilane emulsion coatings were fabricated by sol–gel method with incorporation of rGO-PDA. The PDA molecules, bridging the GO sheets and silane molecules by forming chemical bonds of –NH, CO-NH, and Si-O-C, construct amorphous and dense network structure in the emulsion. The laser particle size analysis shows that GO sheets modified by PDA were dispersed better in silane emulsion. Furthermore, the newly developed silane emulsions were sprayed on the concrete surface, while the water and ions resistance were tested to evaluate the effectiveness of coating materials. The silane emulsions modified by rGO-PDA generate higher hydrophobic effects on concrete surface. The surface contact angles can reach as high as 140° and the capillary absorption rate for water is reduced by 90%. In particular, as the rGO-PDA content is 0.2%, the modified silane emulsions exhibit the highest hydrophobicity. Additionally, the long-term sulfate attack and chloride penetration tests also confirm that as compared with coating without modification, rGO-PDA modified silane emulsions can effectively reduce transport rate of chloride and sulphate ion in concrete by nearly 70%, and alleviate concrete degradation in great extent. This paper presents new ideas for the research of nano-modification of composite silane coatings and provides technical guidance for the surface protection against concrete structures in marine regions.

Effect of silane emulsion on waterproofing and Anti-icing performance of foamed concrete

Foamed concrete has several attractive properties such as low unit weight, high thermal conductivity and good sound insulation as well as being compatible with most building materials. However, the process of forming foamed concrete can also lead to a porous structure within the concrete, leading to increased water absorption and structural defects. This study aimed to investigate the use of silane-based emulsion to reduce the water absorption of foamed concrete. Four types of silane emulsion were synthesized and coated onto the surface of foamed concrete. The hydrophobic performance improved at a temperature of −20 °C, when the waterproof layer was the thickest. The freezing time of water drops on the surface of the concrete was delayed by up to 157% compared to the uncoated control. The silane-based emulsion significantly improved the anti-icing property of the concrete, and they endowed the concrete with superhydrophobicity, creating a self-cleaning effect. These findings show that foamed concrete coated with silane-based emulsion can be used in a broader array of applications and environments.

Study on Mechanical Properties of PVA Modified Cement-based Composites Mixed with Silane Emulsion after Temperature Effect

This article analyzes the basic performance of PVA modified cement-based composite materials, including mechanical properties, durability, and interface bonding issues. The purpose of this article is to clarify the mechanical properties of the modified material and lay the foundation for further optimization of the material ratio. Therefore, the main points of preparation of PVA modified cement-based composite material mixed with silane emulsion in this paper include testing raw materials, design of material mixing ratio, processing of specimen forming process, determination of slump of materials, pouring and maintenance of specimens, etc. the study. And through the study of the material’s flexural strength, load-displacement curve, material’s compressive strength, material’s toughness index, splitting tensile strength, specimen failure form and other mechanical properties analysis.

Improvement in freeze-thaw durability of recycled aggregate permeable concrete with silane modification

Currently, there are few effective methods for improving the freeze–thaw durability of recycled aggregate (RA) permeable concrete without reducing the strength or permeability. Thus, this study aims to improve the freeze–thaw durability of recycled aggregate permeable concrete without the degradation of strength and permeability. Accordingly, two silane emulsion modification methods, namely the surface modification of recycled aggregate and integral modification of cement matrix, were used to raise the freeze–thaw durability. The compressive strength, permeability coefficient, freeze–thaw durability of recycled aggregate permeable concrete were measured. The characteristics of interfacial transition zone (ITZ) and cement matrix were investigated to analyse the modification mechanism. The results indicate that surface modification of recycled aggregate can increase both the compressive strength and freeze–thaw durability of recycled aggregate permeable concrete more effectively than the integral modification of cement matrix. This study provides an effective method to improve the comprehensive performance of recycled aggregate permeable concrete.

Effect of SiO2 Sol/Silane Emulsion in Reducing Water and Chloride Ion Penetration in Concrete

Here, a new concrete hydrophobic treatment method is developed using SiO2 sol and silane emulsion. The effectiveness of the modification for concrete protection is evaluated through testing water absorption and chloride diffusion. Two types of concrete with different strength grades (C40, C50) are used as the research object. The results show that the water capillary absorption coefficient and chloride ion diffusion coefficient of concrete decrease greatly under the protection of SiO2 sol and silane emulsion. Additionally, the protection effect is better with the increase of SiO2 consumption. Contact angle test results reveal that when the coating amount of SiO2 sol and silane emulsion is 300 g/m2, respectively, the contact angle reaches 150.2°, indicating the concrete (C40) surface reaches the superhydrophobic state. Through scanning electron microscope (SEM) observation, it is found that the hydrophobic effect of the SiO2 sol/silane emulsion is mainly due to the change in the surface morphology of concrete (C40).

Experimental Study on Improvement Mechanism of Silane Emulsion on Acid Rain Corrosion of Green Ecological Concrete

Concrete structure is vulnerable to acid rain corrosion, which affects the service life of the material, in the corrosive environment, and concrete structure will deteriorate because of the erosion of water/chloride ions. Therefore, waterproof treatment of concrete structure is needed to improve the durability of the structure. In this study, the green ecological concrete is taken as the research object. The concrete is mixed with a certain amount of silane emulsion to reduce the probability of corrosion of concrete due to moisture and chloride ions, thereby prolonging the service life of this kind of concrete. During the experiment, in order to further test the corrosion resistance of silane emulsion to this kind of concrete, different kinds of concrete were taken as test objects and divided into 3 test groups, namely, the original test group (ITE), the non silane emulsion test group (TWSE) and the optimal ratio test group (OT-SE). It is proved by experiments that the best proportion of concrete mixed with silane emulsion is 0.32 of water binder ratio, 18% of coal powder mixing ratio, 37% of gravel mixing ratio and 0.23% of proportion of silane emulsion. The above factors are applied to compressive strength test, and 30 days as test time, the compressive strength of concrete with fly ash is measured. In the experiment of anticorrosion, compared with the traditional concrete samples, the electrical flux of concrete mixed with silane emulsion decreased by 28.7% in 8 h, that is, chloride ion permeability decreased significantly.

Facile one-step targeted immobilization of an enzyme based on silane emulsion self-assembled molecularly imprinted polymers for visual sensors.

Immobilized enzymes play significant roles in many practical applications. However, the enzymes need to be purified before immobilization by conventional immobilizing methods, and the purification process is expensive, laborious, complicated and results in a decrease of the enzymatic activity. So, we present a novel method by a facile one-step targeted immobilization of an enzyme without a purification process from complex samples. For this purpose, a novel molecularly imprinted polymer was prepared via a silane emulsion self-assembly method using boric acid-modified Fe3O4 nanoparticles as magnetic nuclei, horseradish peroxidase as a template, 3-aminopropyltriethoxysilane as a functional monomer and tetraethyl orthosilicate as a crosslinking agent. The molecularly imprinted polymers were characterized using a scanning electron microscope, X-ray photoelectron spectroscope, vibrating sample magnetometer and X-ray diffractometer. The as-prepared and characterized materials were employed to immobilize horseradish peroxidase from a crude extract of horseradish. Moreover, the immobilized horseradish peroxidase was employed to develop visual sensors for the detection of glucose and sarcosine. This study demonstrated that the molecularly imprinted polymers prepared via the silane emulsion self-assembly method can facilely immobilize horseradish peroxidase from a crude extract of horseradish without any purification process. The developed visual method based on the immobilized horseradish peroxidase shows great potential applications for the visual detection of glucose and sarcosine.

Protective Mechanism of Silane on Concrete upon Marine Exposure

Due to the high chloride ion concentration in marine environments, chloride ions can penetrate into concrete, along with the transportation of water molecules, and thus, cause rebar corrosion. This is an important reason for the decrease in the concrete durability. In this paper, by means of the sol–gel synthesis method, a silane emulsion, a silane compound emulsion, and silane compound gel were prepared by using isobutyl triethoxysilane and ethyl orthosilicate (TEOS) as the main raw materials. These silane materials were coated on a concrete surface and then placed in the marine exposure sites of Wheat Island, in Qingdao, for one year. The results show that these silane materials can effectively inhibit the chloride ions transporting in concrete. Upon the increase of the exposure time, the protection ability of the silane emulsion declined gradually, while the silane compound emulsion had stable protective effects. In comparison with the permeability coefficient of chloride ions in the blank test block, the permeability coefficient of chloride ions in the test block coated with the silane emulsion, the composition of silane emulsion, and silane compound gel fell off around 20%, 30%, and 50%, respectively. The test results indicate that the three kinds of protective materials have good inhibition abilities against chloride ion transportation, on which the compound gel had the best effect.

Preparation and mechanism of graphene oxide/isobutyltriethoxysilane composite emulsion and its effects on waterproof performance of concrete

Abstract In the present paper, graphene oxide (GO) was used to modify isobutyltriethoxysilane. GO/isobutyltriethoxysilane composite emulsion was then prepared by the sol–gel method. The properties of the obtained composite emulsion were characterized by Fourier Transform Infrared (FT-IR), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS). The waterproof performance of GO/isobutyltriethoxysilane composite emulsion was studied by capillary water absorption and water contact angle experiments. The FT-IR results showed that the number of Si–O bonds in the composite emulsion were superior to that in silane emulsion while carboxyl groups were found to be less. This indicated that GO was successfully grafted to the isobutyltriethoxysilane monomer. The XPS data showed that amounts of C–OH in the composite emulsion were lower than those in silane emulsion, suggesting that part of C–OH in the composite emulsion participated in formation of Si–O–C covalent bond between GO and silane. SEM and EDS revealed that the composite emulsion and silane emulsion could form a dense hydrophobic layer on the concrete surface, thereby achieving waterproof effect. Water contact angle and capillary water absorption tests of concrete indicated composite emulsion with significantly improved waterproof performances when compared to silane emulsion.

Carbonation of Water Repellent-Treated Concrete

Water repellent treatment has been considered an effective preventive method against water and aggressive ions penetration into concrete and consequently can improve the durability of concrete structures. In reality, many concrete structures are exposed to conditions with high risk of carbonation. In this contribution, one type of ordinary concrete had been prepared and surface impregnated by 400 g/m2silane cream and 100 g/m2and 400 g/m2silane gel. In addition, integral water repellent concrete was produced by adding 2% silane emulsion. Then, the specimens were exposed to accelerated carbonation for 7, 28, and 72 days. The effect of water repellent treatment on carbonation of concrete has been investigated. The results indicate that surface impregnation reduced carbonation depth of concrete under RH 70%, but integral water repellent concrete increased carbonation. Carbonation reaction started behind the hydrophobic layer in the surface-impregnated concrete. The coefficient of carbonation can be described better by a hyperbolic function of time. Treatment by 400 g/m2silane gel and silane cream showed better efficiency on reducing carbonation than usage of 100 g/m2. Coefficient of water capillary suction was decreased significantly by both surface impregnation and integral water repellent treatment. It is an effective method to protect concrete from water penetration into the material.

Application of neutron radiography in observing and quantifying the time-dependent moisture distributions in multi-cracked cement-based composites

Significant tensile strain capacity of SHCC under tensile stress can be reached by multi-crack formation, while the cracks remain bridged by fibres. Ductility of SHCC is due to this multi-crack formation. Cracks are preferential pathways for ingress of water and salt solutions into the material. In this contribution neutron radiography has been successfully applied to visualize the process of water penetration into cracked SHCC and to quantify the corresponding time-dependent moisture distributions in cracked SHCC. Results indicate that in uncracked SHCC, less water can be found. Once cracked, however, both the amount of water and the penetration depth increased with increasing of crack density and the wider crack pattern when higher tensile strain was applied. Even at comparatively modest imposed strain when micro-cracks were formed, water penetrated into the specimens along the cracks of 30 μm–50 μm immediately and then water migrated further into the surrounding matrix from water filled cracks. Water then moved into the matrix adjacent to the cracks which was mechanically damaged by direct tension. Therefore, if durability of SHCC is an issue for application, a maximum strain may not be exceeded. In order to prevent penetration of water or salt solutions into cracked SHCC, two approaches were used. Integral water repellent SHCC was prepared by adding silane emulsion to the fresh mortar. Compared with neat SHCC, the integral water repellent SHCC with multi-cracks absorbed much less water after imposed to the same tensile strain. Notice that there was still a small amount of moisture that could enter the matrix of integral water repellent SHCC via cracks when the tensile strain was over 1.5% in this study. As an alternative method, surface impregnation with silane gel was a more promising approach to protect cracked SHCC from water or salt solution penetration into the material when multi-cracks formed.

Influence of freeze-thaw cycles on properties of Integral Water Repellent Concrete

Service life of reinforced concrete structures usually was designed on the basis of one selected deteriorating mechanism as for instance carbonation, chloride penetration, and frost action. It could be shown in the meantime by numerous authors, however, that combined actions such as chloride penetration under mechanical load or chloride penetration in combination with freeze-thaw cycles may shorten the service life of reinforced concrete structures more than individual processes acting alone. We have found that chloride penetration is accelerated significantly by freeze-thaw cycles. Frost damage not only reduces mechanical strength and elastic modulus but migration of chloride is facilitated in the damaged pore structure. Chloride penetration can be retarded by the addition of silane emulsion to the fresh concrete. In this way Integral Water Repellent Concrete (IWRC) can be produced. Migration of water and ions dissolved in water can not be prevented by integral water repellent treatment but it is slowed down. The combination of damage mechanisms and the protective measures by integral water repellent treatment have to be taken into consideration in realistic service life prediction and design.

Permeability behavior of integral water-repellent SHCC under applied load conditions

Strain-hardening cementitious composite (SHCC) with PVA fibers possesses a predominant tensile and bending strength. However, attributing to the existence of fibers in SHCC, the high strain is frequently appeared under different applied load conditions. More cracks are formed with the increase in strain, which significantly increases the permeability of SHCC. Mixing silane emulsion into fresh SHCC can prepare integral Water-Repellent SHCC (IWR-SHCC), and it is an effective method for improving the durability and permeability resistance of SHCC. This investigation aims to evaluate the permeability of IWR-SHCC under different applied load conditions. The capillary absorption test is used in this paper to evaluate the permeability behavior of IWR-SHCC. The capillary absorption test was carried out under loading and after unloading, and the water and chloride penetrations were measured. The results show that applied loads have a significant impact on the permeability behavior of IWR-SHCC, and the permeability is proved to increase with the increasing applied loads, and increases with the increase in curing time. Compared to the permeability behavior of SHCC, IWR-SHCC has better permeability resistance under the same applied load condition. Preparing IWR-SHCC is an effective way to improve the permeability resistance of SHCC under applied load condition.

Effect of Octyl-Triethoxysilane Emulsion on Protection of Concrete

In this study, octyl-triethoxysilane emulsion was prepared using octyl-triethoxysilane monomer. The protective effect of the silane monomer and emulsion was investigated on the concrete with different water to cement ratios (0.4 and 0.5). The results showed that octyl-triethoxysilane emulsion displayed efficient protection of concrete. Octyl-triethoxysilane emulsion acquired excellent penetration depth (> 3.7 mm), the water absorption coefficient was reduced by 83.4%, and the chloride ion diffusion coefficient was only 1.8 × 10−12 m2 s−1, reduced by 71.3%. The emulsion also showed good resistance to carbonization and freezing-thawing. The carbonation depth of concrete was reduced by 42%, while the silane monomer has little effect on carbonization. Good protection performance was obtained in the freezing-thawing cycle tests. The relative dynamic elastic modulus was increased by 27%; the mass loss was reduced by 49% after 300 cycles. The protective effect of silane emulsion was also related with the water cement ratio of concrete and the test method. Silane monomer had good waterproof effect and chloride resistance, but poor resistance to carbonization and freezing-thawing. Silane emulsion was a better choice for concrete protection, for it displayed lower rate of volatilization, insignificant toxicity, and better retainment of the active ingredient.