A hydrophobic cement admixture containing asphaltenes

Abstract

The present application relates to an admixture for imparting hydrophobicity to a cement-based composition, comprising asphaltene particles as a hydrophobic agent and at least one surfactant for promoting dispersion. The present application also provides a hydrophobic cement-based composition containing the admixture, and a corresponding cement formulation. The admixture utilizes petroleum by-product asphaltene, significantly improving the waterproofing and corrosion resistance of cement materials while achieving carbon sequestration, and has the advantages of stable quality and low cost.

Description

Technical Field

[0001] This invention relates to the petroleum industry. Specifically, this document describes a cement admixture containing asphaltene that imparts hydrophobic properties to cement-based materials. Background Technology

[0002] Addressing climate change and environmental issues has become a top priority in the 21st century. However, despite recent advancements in the efficiency and storage of renewable energy sources (solar, wind, geothermal, etc.), petroleum remains a reliable medium for meeting society's short- and medium-term energy needs due to its strong cost competitiveness, transportability, and availability. The development of new uses for refinery byproducts offers practical solutions to pressing problems facing downstream processing industries. Similar to the diversification opportunities offered by the rise of petrochemical products derived from light hydrocarbons, novel non-combustible uses of heavy hydrocarbon fractions add incremental economic value, flexibility, and resilience to refinery operations. Furthermore, the non-combustible export of petroleum enables the industry to fulfill its environmental obligations within a green society. If left unaddressed, regulatory costs and impairments associated with reducing carbon emissions could significantly impact the economics of refinery projects.

[0003] Concrete, widely used in the construction of buildings and structures, is composed of cement and aggregates. Cement consumption is the largest of all commodities, reaching 4.1 billion tons in 2023. By design, concrete is a porous, water-wetting material that allows water to pass through its matrix via hydrostatic pressure, water vapor gradients, or capillary action. Over time, water can compromise the integrity of concrete through the following mechanisms: 1) concrete may be susceptible to erosion by dry chemical agents when wetted; 2) internal cracks may form during freeze-thaw cycles of infiltrating water; and 3) water infiltration may corrode or weaken internal reinforcing materials, namely the consumption of sparse water-soluble calcium compounds in the concrete and the corrosion of carbon steel reinforcement. Therefore, the solution to the problem of water damage to concrete is to use hydrophobic cementitious materials with inherent waterproof properties. Furthermore, inherently waterproof cementitious materials also have anti-mold properties. In addition to causing structural damage, mold can lead to serious chronic human health problems and negatively impact the aesthetics of buildings.

[0004] U.S. Patent No. 10,590,038 describes an example of a hydrophobic cementitious material in which recycled waste materials, such as waste rubber tires, recycled plastics, waste catalysts, waste lubricating oil, waste engine oil, base oil, and waste vegetable oil, are used as hydrophobic admixtures in the production of the cementitious material. While recycling and reusing waste is a cautious concept, the cost of processing and treating waste into a usable form for supply is high. For example, in the case of waste tires, the rubber parts are initially separated from steel wire, glass fiber, and other non-rubber materials. Subsequently, the debris-free rubber is recovered by cryogenic freezing using liquid nitrogen or other suitable methods. The rubber is then mechanically ground and sieved into particles of the desired size, typically ranging from 100 to 1000 μm. Furthermore, because they are waste, it is difficult to guarantee the consistency of the quality of the hydrophobic admixture. Hydrophobic cementitious materials prepared using waste oil may not be suitable for general applications, i.e., the emission of volatile organic compounds. More importantly, all these wastes are “man-made” organic compounds with a definite lifespan. In other words, these organic compounds eventually decompose into other compounds that may not possess hydrophobic properties, thus rendering previously hydrophobic cement-based materials non-hydrophobic. From a broader market perspective, the amount of hydrophobic admixtures extracted from waste is limited compared to cement consumption, and the increased costs associated with waste recycling processes may pose a barrier to market adoption. Therefore, an improved method is needed to impart hydrophobicity to cement-based materials. Summary of the Invention

[0005] The purpose of this invention is to provide a cement admixture prepared using petroleum byproduct asphaltene, to solve the problems of high cost and poor stability of existing hydrophobic admixtures, while providing a carbon sequestration pathway for the petroleum industry.

[0006] To achieve the above objectives, the present invention provides a method for preparing an admixture suitable for bonding with cement to form a hydrophobic cementitious composition, the method comprising: The admixture includes asphaltene and at least one surfactant to promote the dispersion of asphaltene in the cement-based composition.

[0007] According to a specific embodiment of the present invention, the asphaltene used in the above-described preparation method is a solid byproduct of solvent deasphalting in petroleum refining processes, such as asphaltene produced by the process described in U.S. Patent No. 7,597,794, asphaltene produced by a selective asphaltene separation (SELEX-Asp™) process described in U.S. Patent No. 7,597,794, asphaltene used as an adsorbent for removing contaminants in U.S. Patent No. 11,446,633, and asphaltene used as a conventional refinery feedstock (DAO) for producing clean transportation fuels as described in U.S. Patent No. 9,925,532. The scope of this description is not limited to the source or means of producing the asphaltene.

[0008] In a specific embodiment of the present invention, the feedstock for the solvent deasphalting process is obtained from the selective asphaltene separation (SELEX-Asp) process described in U.S. Patent No. 7,597,794 (as described above), using vacuum residue (VR) derived from oil sands bitumen as feedstock. Figure 1 A schematic diagram of a low-complexity, low-energy-intensity solvent separation process for extracting asphaltenes from VR is shown. The key components of the solvent separation process are the extractor, solvent container, solid-gas separator, and stripper. The operating temperature of the extractor and solvent container is 140°C–260°C, with a preferred operating temperature range of 150°C–220°C. The operating pressure of the extractor and solvent container is expected to be between 4 MPa and 6 MPa, with a preferred operating pressure of 5 MPa. The asphaltenes obtained are used for further experimental research.

[0009] In a specific embodiment of the present invention, the particle size of the asphaltene particles ranges from 1 μm to 300 μm. Preferably, the particle size is controlled to be less than 200 μm to ensure uniform filling in the cement matrix. The bulk density of the asphaltene particles is 100 kg / m³. 3 -300 kg / m 3 The softening point should be no less than 160℃, preferably within the range of 170℃ to 220℃, to ensure morphological stability under the heat of cement hydration. Tables 1 and 2 show the approximate and elemental analyses of asphaltene. The data indicate that asphaltene derived from oil sands contains high levels of contaminants (metals, sulfur, nitrogen, and coke precursors). Although asphaltene may contain significant amounts of contaminants, they are benign and non-leaching. Asphaltene is also a stable and non-reactive substance. At high temperatures, asphaltene melts into a high-viscosity liquid and can be converted into various structured carbon-based products. Asphaltene can be used in a variety of applications, whether or not it must be activated first.

[0010] Table 1 Approximate analysis of asphaltene

[0011] Table 2 Elemental analysis of asphaltene

[0012] In a specific embodiment of the invention, suitable surfactants for the compositions described herein are listed in U.S. Patent No. 10,590,038. The surfactant may be one or more of the SPAN™ and TWEEN™ series surfactants, and the surfactant used in the admixtures described herein is preferably nonionic. The addition of the surfactant can significantly reduce the interfacial tension between the asphaltene particles and water, thereby forming a stable dispersion system in the cement paste.

[0013] The present invention also provides a hydrophobic cementitious composition comprising cement and the aforementioned admixtures. A cementitious composition refers to a composition containing cement and optionally other known additives; the present invention is not limited to any particular cement or cementitious composition.

[0014] The present invention also provides a cement formulation comprising the hydrophobic cementitious composition described herein and water.

[0015] In the general-purpose hydrophobic mortar embodiment of the present invention, the composition mainly consists of cement, aggregate, and admixtures. The dry weight ratio of asphaltene to cement in the cement-based composition can range from 1:100 to 1:10, including ratios such as 1:100, 1:95, 1:90, 1:85, 1:80, 1:75, 1:70, 1:65, 1:60, 1:55, 1:50, 1:45, 1:40, 1:35, 1:30, 1:25, 1:20, 1:15, and 1:10, as well as other ratios within this range. A preferred ratio of asphaltene to cement is 1:50.

[0016] In another embodiment of the invention for a high-performance corrosion-resistant coating, the composition significantly enhances protective performance through a high concentration of asphaltene. By mass percentage, the composition comprises 25%–50% cement, 30%–60% fine sand, 10%–40% asphaltene particles, and 0.5%–15% surfactant. In a specific preferred formulation, the mass percentages of each component are selected as follows: 30% cement, 50% fine sand, 15% asphaltene, and 5% surfactant. At this ratio, the asphaltene particles can fully interweave with the cement hydration products, forming a dense hydrophobic physical barrier.

[0017] The cement formulation is prepared by mixing the above-mentioned hydrophobic cement-based composition with water, characterized in that the weight ratio (W / C) of water to the hydrophobic cement-based composition is controlled within the range of 0.3:1 to 0.6:1. The specific value of this weight ratio varies depending on the different construction applications: when the formulation is used as a brush coating, to ensure the slurry has suitable consistency and good surface adhesion, the weight ratio of water to the composition is preferably 0.3:1 to 0.5:1, more preferably 0.4:1; when the formulation is used as a spray coating, to meet the pumping requirements and atomization effect of the spraying equipment, the weight ratio of water to the composition is preferably 0.4:1 to 0.6:1, more preferably 0.5:1.

[0018] The beneficial effects of this invention are as follows: 1. The present invention provides a unique application of asphaltene (a petroleum byproduct) as an additive to impart hydrophobic properties to cement-based materials. Asphaltene can be produced economically in large quantities with relatively stable quality. Using asphaltene as a hydrophobic cement admixture will be a better way to fully utilize heavy hydrocarbon fractions in petroleum refining, and also provides an important carbon emission reduction pathway for the petroleum industry.

[0019] 2. Cement-based materials with the additives of this invention exhibit a surface contact angle of 91° to 97°, significantly altering the natural water permeability of cement and drastically reducing water absorption. The dispersion of asphaltene particles not only provides physical barrier properties but has also been shown to promote the formation of more uniform and dense needle-like hydrated calcium silicate (CSH) crystal structures during cement hydration, thereby enhancing the long-term mechanical strength and structural integrity of the material. When used as a coating, the formulation of this invention maintains excellent adhesion even after prolonged immersion (e.g., 45 days) in acidic (1% HCl), alkaline (5% NaOH), and saline environments, effectively preventing oxidation and rusting of the internal metal substrate. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a solvent separation process used to extract asphaltenes from vacuum residue.

[0021] Figure 2 Water droplets on hydrophobic cement mortar containing bitumen.

[0022] Figure 3 a to 3c (collectively referred to as " Figure 3 ") represents the effect of asphalt on the contact angle of water droplets on cement mortar.

[0023] Figure 4 This is a scanning electron microscope (SEM) image of cement mortar with added asphalt. In the image, "CSH" is a CaO-SiO2-H2O substance with a needle-like crystal structure, "CH" is a Ca(OH)2 compound with a flattened crystal structure, and the asphalt has a spherical structure.

[0024] Figure 5 a to 5c (collectively referred to as " Figure 5 The figure shows the effect of asphalt on the microstructure of cement mortar. In the figure, "CSH" is a CaO-SiO2-H2O substance with a needle-like crystal structure.

[0025] Figure 6 a to 6c (collectively referred to as " Figure 6 Energy dispersive X-ray spectroscopy (EDX) analysis of various cements showed the presence of asphaltene in hydrophobic cement mortar.

[0026] Figure 7Energy dispersive spectroscopy (EDS) analysis of various cement mortars showed that the dispersion of elemental species depends on hydrophobicity.

[0027] Figure 8 a represents the application of hydrophobic cement to cardboard boxes using a spraying method.

[0028] Figure 8 b is Figure 8 The hydrophobic cement-coated cardboard box in section a demonstrates its waterproof function.

[0029] Figure 9 a) shows that the hydrophobic cement remained firmly attached to the test sample after being soaked in various chemical reagents for 45 days.

[0030] Figure 9 b represents the corrosion marks on the unprotected surface of the test sample after immersion in various chemical reagents for 45 days.

[0031] Figure 10 a is Figure 9 The test specimen in section a was scraped off its top layer, exposing the complete hydrophobic cement. Furthermore, no corrosion was observed on the test specimen when the hydrophobic cement layer was removed.

[0032] Figure 10 b is Figure 10 Spherical water droplets on the uncovered hydrophobic cement in section a.

[0033] Figure 11 The hydrophobic cement-coated fasteners did not rust after being exposed to the outdoor environment for one year, while the unprotected fasteners rusted. Detailed Implementation

[0034] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0035] Example 1 This embodiment provides a hydrophobic cement admixture, and the influence of asphaltene on the performance of cement mortar is determined through a series of experimental studies: On one hand, a series of cement mortar samples were prepared using Portland cement (silicate cement), standard #4 sand, chemical reagents, and asphaltene. Table 3 shows the composition of the cement mortar samples. Sample A is a standard cement mortar mixture composed of dry cement and standard fine sand. In this work, Sample A is referred to as the control sample. Samples B and C also contain a chemical reagent, which is a nonionic surfactant described in US Patent No. 10,590,038. Surfactants were added to these test samples to ensure that the oil-based asphaltene was adequately dispersed in the cement mixture. Sample A did not require a surfactant, and different amounts of asphaltene were added to Samples B and C. Samples A, B, and C were used for further experimental studies, as described in Examples 2 and 3 below.

[0036] Table 3. Composition of cement mortar samples

[0037] As previously stated, in samples B and C, the dry weight ratios of asphaltene to cement in the cement-based compositions were 1.3:100 and 1:50, respectively. Similarly, the surfactant used in samples B and C had a surfactant-to-cement weight ratio of 1:50. However, those skilled in the art will understand that the amount of surfactant used will vary depending on the amount of asphaltene used in the composition and the characteristics of the surfactant (e.g., the HLB (hydrophilic-lipophilic balance) value of the surfactant, etc.).

[0038] For each cement mortar sample, duplicate samples were prepared. The cement mortar was prepared according to GB-T 1346-2011 (ISO 9597,2008) standard (Test methods for normal consistency, setting time and soundness water requirement of silicate cement).

[0039] Various tests were conducted on cement mortar samples according to JC 474-2008 "Standard for Waterproofing Agents for Mortar and Concrete" and the ASTM C109 standard test method to determine the compressive strength of hydraulic cement mortar. Table 4 shows the average values ​​of six replicate samples for each type of cement mortar. The results indicate that samples B and C are excellent waterproof mortars, demonstrating that asphaltene is a good hydrophobic cement admixture. Based on these test results, using asphaltene as a hydrophobic admixture, the dry weight ratio of asphaltene to cement in the cement mixture is expected to be approximately 1:100 to 1:10. The preferred ratio is approximately 1:50.

[0040] Table 4. Test Results of Cement Mortar Samples - JC 474-2008 Mortar Standard, Concrete Waterproofing Agent

[0041] Example 2 This embodiment provides a test result of the hydrophobicity of cement mortar modified by asphalt.

[0042] Add water droplets to the surface of the broken cement mortar sample C, such as Figure 2 As shown, the water droplets are spherical, indicating that sample C cement mortar is hydrophobic. This suggests that asphaltene is a good hydrophobic cement admixture.

[0043] Water droplets were added to the surface of cement mortar samples A, B, and C, such as... Figure 3 As shown, the water droplets are all different shapes. Figure 3 The study also shows the contact angle measurements of water droplets on various cement mortar surfaces. The results indicate that the water droplets on sample A are relatively flat, with a contact angle of 25-26°. This is expected, as sample A is a standard water-wet cement mortar. The water droplets on samples B and C are spherical, with contact angles of 74-79° and 91-97°, respectively. This suggests that sample C has stronger hydrophobicity (water resistance) than sample B, indicating that the amount of asphaltene has a positive effect on the hydrophobicity of cement mortar.

[0044] Example 3 This embodiment provides a method for altering the microstructure of cement using asphaltene.

[0045] Scanning electron microscopy (SEM) analysis was performed on fragments of broken cement mortar samples to determine the influence of asphaltene on the microstructure of cement mortar. Figure 4 This is a 10k magnified SEM image of cement mortar sample C. The abundance is characterized by acicular hydrated calcium silicate (CSH), platy calcium hydroxide (CH), and generally spherical asphaltene. Aluminate-ferrite-trisulfate ettringite (AFT) with a columnar structure was observed, but rarely. The presence of CSH is known to be preferred in techniques for improving cement strength, as CSH acts as a strong binder that imparts strength to cement. Further investigation into CSH in various cement mortars is sought.

[0046] Figure 520k magnified SEM images of cement mortar samples A, B, and C are shown, focusing on the CSH material. The microstructure of the CSH material in sample A is not well-defined compared to samples B and C. As expected, the CSH material in samples B and C exhibits a needle-like crystalline structure. This suggests that using asphaltene as a hydrophobic admixture has the potential to more uniformly modulate the cement hydration reaction, resulting in a uniform needle-like structure. The needle-like structure of the CSH material in sample C is more uniform and well-defined compared to sample B. Since sample C contains more asphaltene, it is more hydrophobic than sample B (as described in Example 3 above), which also supports the hypothesis that the cement hydration reaction is hydrophobic-dependent. In summary, adding asphaltene as a hydrophobic cement admixture may improve the long-term integrity of cement by increasing its strength and preventing the depletion of sparse, water-soluble calcium compounds.

[0047] Energy-dispersive X-ray spectroscopy (EDX) analysis was performed on various types of cement, such as... Figure 6 As shown, the presence of nickel and vanadium in samples B and C is very evident because petroleum-derived asphaltene was added as a cement admixture.

[0048] Energy dispersive spectroscopy (EDS) analysis was performed on various cement mortars, such as... Figure 7 As shown, different dots represent various element types in cement mortar. The dot pattern indicates the dispersion of various element species in the cement mortar. Comparing the dot patterns, sample C has the most uniform species distribution, while sample A has poorer dispersion. This indicates that the dispersion of element species depends on hydrophobicity.

[0049] Example 4 This embodiment provides a novel application of the hydrophobic cement mixture, which can be used as a sprayable hydrophobic coating material. The hydrophobic cement mixture was prepared using the composition shown in Table 5.

[0050] Table 5 Composition of sprayable hydrophobic cement mixtures

[0051] In this example, the sprayable cement mixture comprises a dry weight ratio of asphalt to cement of 1:2. The dry weight ratio of surfactant to cement is 1:6 (i.e., 16.7%).

[0052] Add an appropriate amount of water to the hydrophobic cement mixture to ensure consistent spray flow; the ratio is approximately 0.5:1. Transfer the slurry-like hydrophobic cement mixture into the spray gun's container and mix thoroughly. Figure 8 As shown in Figure a, a hydrophobic cement mixture is sprayed onto the inner surface of a cardboard box. After drying for a day, the cardboard box becomes a waterproof container, as shown in Figure a. Figure 8As shown in b, this indicates that hydrophobic cement is a good waterproof coating material and has adhesive properties to materials other than cement-based materials.

[0053] Example 5 This embodiment confirms that the hydrophobic cement mixture used in Example 4 (described above) also possesses hydrophobicity and corrosion resistance. A series of side-by-side corrosion tests were conducted using the hydrophobic cement mixture. Adding water to the hydrophobic cement mixture at a ratio of approximately 0.4:1 ensured consistent brushing flowability.

[0054] Carbon steel test specimens were used, without surface treatment. A hydrophobic cement mixture was applied to one side of the test specimen with a brush. One specimen was coated with Portland cement (silicate cement) as a control. The chemical reagents used for corrosion testing were sulfuric acid, sodium hydroxide, and sodium chloride. All test specimens were immersed in the various chemical reagents.

[0055] After soaking in chemical reagents for one day, the cement material detached from the test specimen coated with Portland cement (silicate cement), indicating that ordinary cement alone is not a good anti-corrosion coating material and exhibited decreased adhesion. After soaking in chemical reagents for 45 days, the hydrophobic cement remained firmly adhered to the test specimen, as... Figure 9 As shown in Figure 9a, surface discoloration is due to the reaction of the calcium on the surface with the chemical reagents, resulting in the formation of a protective surface layer. Figure 9b shows the reverse side of the unprotected test sample. Unsurprisingly, corrosion marks are present.

[0056] On the other hand, the hydrophobic cement mixture can be applied by spraying. The amount of water added to the hydrophobic cement mixture ensures consistent flowability during brushing, and is expected to range from approximately 0.4:1 to approximately 0.6:1. In one embodiment, a ratio of approximately 0.5:1 is preferred. Figure 10 The results show that calcium forms a protective layer on the surface of the hydrophobic cement. Scraping away the top layer and the hydrophobic cement from the test sample surface indicates that the hydrophobic cement remains intact beneath the surface, and the test sample shows no corrosion. Figure 10 b shows spherical water droplets on hydrophobic cement, indicating that the hydrophobicity of the cement remains intact.

[0057] Figure 11 shows that the hydrophobic cement-coated fasteners did not rust after one year of exposure to the outdoor environment, while the unprotected fasteners rusted as expected. This again demonstrates the corrosion resistance of hydrophobic cement.

[0058] Hydrophobic and corrosion-resistant coated cement will be an excellent protective material for concrete and metal structures in marine environments, and is also suitable for other non-marine applications where corrosion is a risk. Furthermore, because cement-based materials are inorganic, hydrophobic and corrosion-resistant coated cement is a durable coating material, unlike organic materials which deteriorate over time.

[0059] The above content is a further detailed description of the technical solution of the present invention in conjunction with specific preferred embodiments, and should not be construed as limiting the scope of implementation of the present invention. For those skilled in the art, several simple deductions or substitutions can be made without departing from the present invention, and all of these should be considered as falling within the patent protection scope defined by the claims submitted by the present invention.

Claims

1. A cement admixture for imparting hydrophobicity to cement-based compositions, the admixture comprising a hydrophobic agent and a surfactant, wherein the hydrophobic agent comprises asphaltene particles.

2. The mixture of claim 1, wherein, The surfactant is nonionic.

3. The mixture according to claim 1 or 2, wherein, The particle size of the asphalt particles is from about 1 μm to about 300 μm.

4. A hydrophobic cementitious composition comprising cement and an admixture according to any one of claims 1 to 3.

5. The hydrophobic cementitious composition according to claim 4, characterized in that, The dry weight ratio of asphaltene to cement in the cement-based composition is approximately 1:100 to approximately 1:

2.

6. The hydrophobic cementitious composition according to claim 4, characterized in that, The dry weight ratio of asphaltene to cement in the cement-based composition is approximately 1:100 to approximately 1:

50.

7. The hydrophobic cementitious composition according to claim 4, characterized in that, The dry weight ratio of asphaltene to cement in the cement-based composition is approximately 1:10 to approximately 1:

2.

8. According to any one of claims 4 to 7, the weight percentage of asphaltene in the hydrophobic cementitious composition is from about 10% to about 40%.

9. According to any one of claims 4 to 8, the surfactant in the hydrophobic cementitious composition is present in the hydrophobic cementitious composition at a concentration of about 0.5% w / w to about 15% w / w.

10. According to any one of claims 4 to 9, the weight percentage of cement in the hydrophobic cementitious composition is from about 25% to 50% w / w.

11. The composition of any one of claims 4 to 10, further comprising sand and / or aggregate.

12. The hydrophobic cementitious composition of any one of claims 4 to 10 further comprises sand in weight percentages ranging from about 30% to 60% w / w.

13. A cement formulation comprising a hydrophobic cementitious composition of any one of claims 4 to 12 and water.

14. The cement formula according to claim 13, characterized in that, The weight ratio of water to hydrophobic material in the cementitious composition ranges from about 0.3:1 to about 0.6:

1.

15. The cement formula according to claim 14, characterized in that, The water to hydrophobic water weight ratio of the cementitious composition ranges from about 0.4:1 to about 0.5:

1.

16. The cement formula is as described in claim 14 or 15, wherein, The formulation is a form for application as a coating on a surface.

17. The cement formula according to claim 16, wherein, The formulation is available in sprayable or brushable form.

18. Using the cementitious preparation of any one of claims 14 to 17 as a coating to impart hydrophobicity and / or corrosion resistance to a substrate.

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