Color compatibility method for repairing concrete structure by using inorganic cementing material

Abstract

The invention discloses a color compatibility method for repairing a concrete structure by using an inorganic cementing material. The whole-process repairing method of matrix concrete color detection and surface evaluation, repairing mortar pigment mixing amount design, repairing construction, color compatibility evaluation and long-term monitoring and maintenance is adopted, and the method has the advantages of precise color regulation and control, collaborative optimization of functions and aesthetics, wide adaptability and long-term stability and reliability; the problems that in a traditional concrete repairing project, only the mechanical property and durability of materials are concerned, color coordination is neglected, consequently, an obvious patch effect is formed in a repairing area, and chromatic aberration is likely to occur after long-term service are effectively solved, double guarantees of the structure repairing effect and appearance visual uniformity are achieved, the operation process is standard and controllable, and the repairing cost is low. The method is suitable for various concrete structure repairing scenes.

Description

Technical Field

[0001] This invention relates to the field of reinforced concrete structure repair technology, specifically to a method for color compatibility repair of concrete structures using inorganic cementitious materials. Background Technology

[0002] In recent years, under the combined effects of environmental erosion and external loads, concrete structures are prone to corrosion failure during their service life, and some even face premature decommissioning. Such problems are frequent. Repair and reinforcement, as the most economical and effective means of extending the service life of concrete structures, directly affect the safety and durability of infrastructure through the selection and application of repair technologies, with the performance of repair materials playing a decisive role. Currently, the selection of concrete structure repair materials mainly focuses on core indicators such as physical and mechanical properties, durability, and ease of construction. However, in actual repair projects, the color coordination between the repair material and the original structure is often overlooked, resulting in a noticeable "patchwork" effect in the repaired area, severely impacting the overall aesthetics of the repaired structure. This problem is particularly prominent in scenarios with high requirements for appearance, such as municipal landscape projects and transportation infrastructure. Therefore, how to achieve a synergistic unity between structural performance and aesthetic effects during the repair process has become one of the key issues that urgently need to be addressed in the field of concrete repair.

[0003] Color compatibility in restoration projects specifically refers to the visual consistency of color between the restoration material and the base concrete, encompassing both initial static compatibility and dynamic compatibility. Initial static compatibility requires that the color difference between the restored material and the base concrete after hydration be below an acceptable threshold. Dynamic compatibility emphasizes the synchronous aging and unidirectional fading of both materials to prevent significant color differences from reappearing after long-term structural service. In recent years, color compatibility and color stability have gradually become important indicators for evaluating the effectiveness of concrete restorations, with their importance becoming increasingly prominent in public facility construction and historical building preservation. Therefore, further in-depth research and optimization are needed regarding existing methods for adjusting color compatibility in restoration projects and on-site construction and testing techniques.

[0004] In the process of color mixing for repair mortar, adding pigments with different gradient dosages will result in mortars exhibiting various colors. Furthermore, the surface color of the mortar is also influenced by factors such as the type of repair mortar and the water-cement ratio. Existing research, in order to simplify the color mixing process, has primarily focused on white mortar, without fully considering the actual application scenarios of commonly used repair mortars in engineering. In fact, the colors and surface morphologies of the same type of colored mortar exhibit significant differences after adding pigments. Therefore, the preparation and application of colored mortars have attracted considerable attention from scholars. Existing studies have set pigment dosage ranges from 0% to 7%, concluding that the saturated pigment dosage is approximately 5%. They have also found a correlation between the compressive strength of the mortar and changes in color parameters in the CIELAB color space as the pigment dosage changes. Currently, there are cases of preparing color-compatible repair mortars by adding a quantitative amount of pigment to the mortar, and these have been applied to several ancient building restoration projects. Additionally, scholars have developed the "Patch Repair Method (PRM)" for the assessment and intervention of concrete heritage restoration, and have formulated design and application guidelines for colored and gray concrete surface repair mortars. However, existing technologies still face many challenges. One key difficulty is the treatment of the transition zone between the base concrete and the repair mortar. Furthermore, most research still relies on repair experience for color control, lacking precise and systematic quantitative research on the relationship between the color of the base concrete, the color of the repair mortar, and the added pigments. Therefore, existing methods for color compatibility adjustment and on-site construction testing techniques in repair projects need further improvement to achieve the goal of "structural and aesthetic dual repair."

[0005] The advantages of magnesium phosphate cement (MPC) mortar in terms of physical and mechanical properties and durability have been fully verified, but systematic research on its color compatibility is still insufficient, especially lacking. There is a lack of quantitative analysis and effective color control methods. To fill this technological gap, this invention uses MPC mortar as a research medium and systematically explores the color stability and visual consistency of MPC mortar under different pigment dosages by introducing inorganic pigments, providing technical support for related engineering applications. Summary of the Invention

[0006] To address the problems mentioned in the background art, the present invention aims to provide a method for color compatibility of inorganic cementitious materials in repairing concrete structures. This method has the advantages of precise color control, synergistic optimization of function and aesthetics, wide adaptability, and long-term stability and reliability. It solves the problems in existing concrete repair projects, such as poor color coordination leading to a "patch" effect, lack of precise quantitative relationship between the matrix and the color of the repair mortar and the amount of pigments, reliance on experience-based control, and insufficient long-term color stability.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for repairing the color compatibility of concrete structures using inorganic cementitious materials, the method comprising the following steps: (1) Color detection and surface evaluation of the base concrete: The reference color of the base concrete is quantified based on the CIELAB color space, and the mechanical performance requirements of the required repair mortar are determined by combining the detection of surface damage morphology of the base concrete. (2) Design of pigment dosage in repair mortar: Under the premise of ensuring the mechanical and durability properties of the repair mortar, the mass ratio of pigments added is calculated through a color control model. The color control model includes: ① Calculation of single pigment dosage: The color difference between the target color (base concrete color) and the MPC mortar reference color is calculated using the following formula:

[0008] ② Calculation of the dosage of multiple pigments in a compound formulation: This matrix is ​​named the correction coefficient matrix. For color coefficient matrix, The dosing matrix for the six pigments is obtained through the following matrix operations. By integrating the color parameters of multiple pigments, and then solving the matrix, the optimal dosing matrix of the multiple pigments is obtained. :

[0009] (3) Repair construction: The transition area between the substrate and the repair area is treated with a layered gradient construction process, and the surface is smoothed after the construction is completed; (4) Color compatibility assessment: After initial setting, the color is measured by an instrument for 1 hour. There are no fewer than 10 test points in the same area. The color difference is calculated according to ISO 11664-4 standard. Determine color compatibility and verify visual uniformity according to the ASTM D1729 visual evaluation method; (5) Long-term monitoring and maintenance: After the repair is completed, a corresponding maintenance strategy is formulated based on the local ultraviolet radiation intensity and temperature and humidity parameters to achieve color compatibility repair through quantitative detection, dynamic color control and long-term durability observation.

[0010] As a preferred embodiment of the present invention, the inorganic pigments selected include the following: Inorganic pigments include six types: titanium dioxide, iron oxide black, iron oxide red, iron oxide green, iron oxide blue, and iron oxide yellow.

[0011] As a preferred embodiment of the present invention, the color space selected is the CIELAB color space: The CIELAB color space used in this invention is designed based on human visual perception, with the goal of achieving linear uniformity as perceived by humans. Its three main axes represent... Color represents brightness (0-100). Represents green-red (-128~128). Representing the blue-yellow axis (-128 to 128), the CIELAB color space has color uniformity; it is visually equidistant, meaning the Euclidean distance between two colors in space is (…). It is similar to the difference perceived by the human eye.

[0012] As a preferred embodiment of the present invention, the model calculation includes the following steps: This invention suggests that since the pigment dosage required for the color range of general repair projects is relatively small (0-12%), magnesium phosphate mortar and the added pigment can be regarded as two phases, and the final LAB value can be considered by linear fitting. Because the addition of pigments causes a hydration reaction between the pigments and the repair mortar, rendering the linear formula invalid, a correction factor is introduced. As an adjustment, it is related to the degree of dispersion of different pigments in x-mortar and whether they react with the components in MPC mortar. For ease of calculation, a color coefficient is also introduced. It is determined by the properties of the pigment itself, and is the difference between the color value of the pigment and the reference coordinate value of the mortar. This study designed a gradient dosing experiment for six pigments: white, red, green, yellow, and blue pigments at 0–12%, and black at 0–3%. The influence of pigment type and dosage on the color parameters of MPC mortar was analyzed, a linear repair color matching model under the influence of a single pigment was obtained, and a color coefficient matrix was proposed. and correction coefficient matrix Establish a linear model to solve for pigment dosage. This led to the establishment of a color-matching matrix applicable to the calculation of various pigment dosages, enabling color control in any concrete repair project. Ultimately, a color compatibility repair method was established, combining quantitative detection, dynamic color control, and long-term durability observation.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention adopts a full-process repair method consisting of "substrate concrete color detection and surface evaluation - repair mortar pigment dosage design - repair construction - color compatibility evaluation - long-term monitoring and maintenance". This method has the advantages of precise color control, functional and aesthetic synergy optimization, wide adaptability and long-term stability and reliability. It effectively solves the problem in traditional concrete repair projects that only focus on the mechanical properties and durability of materials and ignore color coordination, resulting in obvious "patch" effect in the repair area and color difference after long-term service. It achieves dual protection of structural repair effect and visual uniformity, and the operation process is standardized and controllable, adaptable to various concrete structure repair scenarios.

[0014] 2. This invention achieves its goals through the precise selection of six commonly used inorganic pigments, the accurate application of the CIELAB color space, and the inclusion of a color coefficient matrix. With the correction coefficient matrix The linear model calculation settings further improve the accuracy and adaptability of color compatibility repair. Among them, specific inorganic pigment combinations meet the repair needs of different color systems, the CIELAB color space ensures the linear uniformity of color perception and detection accuracy, and the linear model realizes the quantitative calculation of pigment dosage and the scientific control of multi-pigment compounding. It effectively solves the problems of traditional repair relying on experience to adjust color, lack of quantitative relationship between pigment dosage and color parameters, and insufficient accuracy of compound color matching. At the same time, it takes into account the influence of hydration reaction of repair materials and long-term color stability, providing more targeted and scientific technical support for concrete repair in different complex scenarios. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of CIELAB color space conversion; Figure 2 For the dosage of a single pigment and at 28 days , and Linear fitting relationship graph of values; Figure 3 A schematic diagram of the geometric shape of the MPC color space; Figure 4 This is a schematic diagram of the results of the co-doping experiment; Figure 5 This is a schematic diagram of the color compatibility repair process. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] To address the aforementioned technical problems, the technical solution of this invention is as follows: The influence of pigment type and dosage on the color parameters of MPC mortar is analyzed, a linear repair color matching model under the influence of a single pigment is obtained, and a color coefficient matrix is ​​proposed. and correction coefficient matrix Establish a linear model to solve for pigment dosage. This allows for the establishment of a color-matching matrix suitable for calculating the dosage of various pigments, and applicable to color control in any concrete repair project.

[0018] This invention discloses a color compatibility restoration method, analyzes the influence of pigment type and dosage on the color parameters of MPC mortar, obtains a linear restoration color matching model under the influence of a single pigment, and proposes a color coefficient matrix. and correction coefficient matrix Establish a linear model to solve for pigment dosage. This led to the establishment of a color-matching matrix applicable to the calculation of various pigment dosages, suitable for color control in any concrete repair project. Finally, a color compatibility repair method based on quantitative detection, dynamic color control, and long-term durability observation was established. The feasibility of color matching when transitioning from the MPC color system to the concrete color system was verified through laboratory multi-admixture experiments, and the error between predicted and experimental values ​​was studied. <3.

[0019] A color compatibility restoration method includes the following steps: (1) Color detection and surface evaluation of the base concrete: First, the reference color of the base concrete is quantified based on the CIELAB color space ( , , Then, combined with the damage morphology detection of the base concrete surface, the mechanical performance requirements of the required repair mortar are determined; (2) Design of pigment dosage in repair mortar: Calculate the mass ratio of pigments to be added, under the premise of ensuring the mechanical properties and durability of the repair mortar; (3) Repair construction: During the construction phase, a layered gradient construction process is used to treat the transition zone between the substrate and the repair area. After the construction is completed, the surface is smoothed. (4) Color compatibility assessment: After initial setting, the color is measured by an instrument 1 hour later. More than 10 test points in the same area are required, and the color difference is calculated according to ISO 11664-4 standard. Determine color compatibility and verify visual uniformity according to the ASTM D1729 visual evaluation method; (5) Long-term monitoring and maintenance: After the repair is completed, a corresponding maintenance strategy is formulated based on the local ultraviolet radiation intensity and temperature and humidity parameters, and finally the quantitative detection-dynamic color control-long-term durability observation color compatibility repair method is completed.

[0020] The color compatibility color grading model includes the following: Magnesium phosphate mortar and the added pigments can be considered as two phases, and the final... , and The values ​​are considered for linear fitting. , and The values ​​should be considered separately, and the magnesium phosphate repair mortar... , and The extreme value is the value of the pigment added. , and Value. The target color. , and Considering them separately, the mass ratio of magnesium phosphate mortar is (1- The component mass ratio of the pigment is ), As the pigment dosage increases, the color of the repair mortar gradually approaches the color of the pigment from the baseline value. If a linear model is established between pigment dosage and color change, then the expression of the target color (…) , and (1) can be shown in Eq.(1).

[0021]

[0022] in , and Indicates the MPC reference coordinate value. , and Indicates the color value of the pigment. , and This indicates the desired target color value.

[0023] Because the addition of pigments causes a hydration reaction between the pigments and magnesium phosphate cement repair mortar, rendering the linear formula invalid, a correction is introduced. Correction coefficient As an adjustment, it is related to the degree of dispersion of different pigments in MPC mortar and whether they react with the components in MPC mortar. For ease of calculation, a color factor is also introduced. The target color is determined by the properties of the pigment itself; it is the difference between the pigment's color value and the MPC mortar reference coordinate value. , and It can be represented by Eq.(2).

[0024]

[0025] The color difference between the target color and the MPC reference color can be represented by Eq.(3).

[0026]

[0027] In color compatibility restoration, the amount of a single pigment is generally insufficient to meet the restoration requirements. Based on the characteristics of the CIELAB color space, generally, using n pigments will achieve the desired color. Under this assumption, when n kinds of pigments are added, it still satisfies the linear regression relationship, as shown in Eq.(4).

[0028]

[0029] Therefore, the target color , and The following matrix can be used to represent this, and in subsequent calculations, the type and amount of pigment required to achieve the target color can be calculated using the matrix.

[0030]

[0031] in, The desired color matrix represents the color of the base concrete. It serves as the base color for MPC. The range is 1 to n, representing n types of pigments among white, black, red, green, yellow, and blue pigments. This matrix is ​​named the correction matrix. This is the color path matrix. This is the doping matrix for the six pigments, where...

[0032]

[0033] The color difference between the resulting color and the target color can then be represented as follows:

[0034] in The actual color of the repair mortar after color matching, i.e., the final color.

[0035] To achieve a repair mortar color that closely matches the base concrete color after pigment incorporation, the optimization goal is to minimize... ,make ,but It can be expressed by the following formula: (8) in, ,

[0036] To minimize ,we will Set it to 0 and solve.

[0037] (9) Solving for the optimal doping amount : (10) Because of the matrix The missing information necessitates the design of subsequent experiments to obtain the matrix. That is, to solve for the color coefficients and correction factor And the matrix was obtained through result analysis. .

[0038] Case Study: To verify the applicability of the pigment-CIELAB fitting relationship established based on single-admixture experiments under mixed-admixture conditions, and to demonstrate that simple-colored matrix repair projects can be carried out by incorporating a single pigment, this case study uses a magnesium phosphate mortar-inorganic pigment system to verify its feasibility in concrete repair projects.

[0039] Six dosing gradients were designed for different pigments. For white, red, green, blue, and yellow pigments, dosing gradients were set with equal increments of 2%, specifically 0%, 2%, 4%, 6%, 8%, 10%, and 12%. For black pigment, which has a stronger tinting capacity and a lower saturation dosing, a more refined dosing gradient was used, namely 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, and 3%.

[0040] The mortar used in this case is magnesium phosphate repair mortar. The MPC repair mortar used contains recalcined magnesium oxide (recalcined MgO), which was calcined at 1800℃ and has a specific surface area of ​​285m². 2 / kg; Ammonium dihydrogen phosphate (NH4H2PO4), density 2.34 g / m³ 3 The purity is 99%; the borax retarder (Na2B4O7·10H2O) has a density of 1.70 g / m³. 3 The purity is 96%; it is a highly active silica fume with an activity index of 110% after 28 days and a specific surface area of ​​6500 m². 2 / kg, with an average particle size of 4.32μm; ultrafine low-calcium fly ash, with a specific surface area of ​​860m². 2 / kg, with an average particle size of 8.70μm. m(reburned MgO):m(NH4H2PO4):m(Na2B4O7·10H2O):m(fly ash):m(sand):m(water) = 70:20:3.5:11:110:17.6.

[0041] The magnesium phosphate repair mortar used in this case has the following reference coordinates. It is 43.55. It is 2.23. It is 9.62.

[0042] This case study utilizes a commonly used inorganic pigment system in restoration projects. Six inorganic pigments—titanium dioxide, iron oxide black, iron oxide yellow, iron oxide blue, iron oxide red, and iron oxide green—were employed, and their dosages were adjusted to control the color changes of the restoration mortar. The main color parameters are shown in the table below.

[0043] Table 1 Inorganic Pigments , and value

[0044] The pigment content and its relationship after 28 days were obtained at the single pigment dosage. , and Relationship such as Figure 2 As shown, linear fitting was performed on the experimental data of single pigment dosage. Comparison between measured and predicted values ​​shows that the fitting error is less than the color difference threshold that the human eye can perceive. The MPC color space is as follows: Figure 3 As shown, color coefficient ( ) and correction factor ( As shown in Table 2.

[0045] Table 2 MPC Mortar and Inorganic Pigment System and Value

[0046] For restoration projects involving complex colors, a compounding approach is used. Green and black pigments were selected for compounding experiments; the green pigment's effect on... The shaft has a significant adjusting effect, while the black pigment mainly affects... The axes, when combined, can simultaneously act on different color channels and... The axis influences the mortar color, thereby adjusting it towards the target concrete color system, specifically from a black-red-yellow system to a black-white-green-yellow system. Based on the above, experimental admixtures were set at (0.5% black, 1.0% green), (1.0% black, 1.0% green), (1% black, 2% green), (1.5% white, 1% green), (3% white, 1% green), and (3% white, 2% green) to verify the linear response and prediction effect of the linear model under multi-pigment conditions.

[0047] This experiment predicted the theoretical performance of compounded mortar by substituting the compounded mix proportions into the fitting formula obtained from the single-mixed mix experiments. , , The coordinates, i.e. the target color, are compared with the color results from the multi-component experiment. Its calculation formula is shown in Eq. (11).

[0048] (11) in, , , For target color, , , Result color.

[0049] The following results were obtained from the experiment. The predicted and experimental values ​​of the 28-day mixed-doped sample are shown in Table 3 below, including... , , Three color components, and The experimental results show that the model predictions and experimental values ​​generally agree well with each blending ratio. Specifically, L... The prediction error of the value is small, and the largest The error was -0.59, while most proportions... The values ​​are all below 0.5, indicating that the model's prediction of brightness is relatively accurate. The prediction error for the value is slightly large, with a maximum of The value is 1.66, but the difference between most predicted values ​​and experimental values ​​remains within 1.00, which meets the actual color matching requirements. The prediction error of the value is relatively small. The maximum difference was 0.33. All values ​​are below 3. The predicted color of the test block is compared with the color obtained from the experiment. Figure 4 As shown, the model meets the acceptable color difference standard for concrete repair projects, indicating that the model has high accuracy in predicting color tone and can be applied in actual projects.

[0050] Table 3 Comparison of predicted and experimental values ​​from the mixed-component experiment.

Claims

1. A method for color compatibility repair of concrete structures using inorganic cementitious materials, characterized in that: The method includes the following steps: (1) Color detection and surface evaluation of the base concrete: The reference color of the base concrete is quantified based on the CIELAB color space, and the mechanical performance requirements of the required repair mortar are determined by combining the detection of surface damage morphology of the base concrete. (2) Design of pigment dosage in repair mortar: Under the premise of ensuring the mechanical and durability properties of the repair mortar, the mass ratio of pigments added is calculated through a color control model. The color control model includes: ① Calculation of single pigment dosage: The color difference between the target color (base concrete color) and the MPC mortar reference color is calculated using the following formula: 2.② Calculation of the dosage of multiple pigments in a compound formulation: This matrix is ​​named the correction coefficient matrix. For color coefficient matrix, The dosing matrix for the six pigments is obtained through the following matrix operations. By integrating the color parameters of multiple pigments, and then solving the matrix, the optimal dosing matrix of the multiple pigments is obtained. :

3. (3) Repair construction: The transition area between the substrate and the repair area is treated with a layered gradient construction process, and the surface is smoothed after the construction is completed; (4) Color compatibility assessment: After initial setting, the color is measured by an instrument for 1 hour. There are no fewer than 10 test points in the same area. The color difference is calculated according to ISO 11664-4 standard. Determine color compatibility and verify visual uniformity according to the ASTM D1729 visual evaluation method; (5) Long-term monitoring and maintenance: After the repair is completed, a corresponding maintenance strategy is formulated based on the local ultraviolet radiation intensity and temperature and humidity parameters to achieve color compatibility repair through quantitative detection, dynamic color control and long-term durability observation.

4. A method for color compatibility repair of concrete structures using inorganic cementitious materials, characterized in that: Its inorganic pigment selection includes the following: Inorganic pigments include six types: titanium dioxide, iron oxide black, iron oxide red, iron oxide green, iron oxide blue, and iron oxide yellow.

5. A method for color compatibility of inorganic cementitious materials in repairing concrete structures, characterized in that: Its color space selection is CIELAB color space: The CIELAB color space used in this invention is designed based on human visual perception, with the goal of achieving linear uniformity as perceived by humans. Its three main axes represent... Color represents brightness (0-100). Represents green-red (-128~128). Representing the blue-yellow axis (-128 to 128), the CIELAB color space has color uniformity; it is visually equidistant, meaning the Euclidean distance between two colors in space is (…). It is similar to the difference perceived by the human eye.

6. A method for color compatibility repair of concrete structures using inorganic cementitious materials, characterized in that: Its model The calculation includes the following steps: This invention suggests that since the pigment dosage required for the color range of general repair projects is relatively small (0-12%), magnesium phosphate mortar and the added pigment can be regarded as two phases, and the final LAB value can be considered by linear fitting. Because the addition of pigments causes a hydration reaction between the pigments and the repair mortar, rendering the linear formula invalid, a correction factor is introduced. As an adjustment, it is related to the degree of dispersion of different pigments in the mortar and whether they react with the components in the MPC mortar. For ease of calculation, a color coefficient is also introduced. It is determined by the properties of the pigment itself, and is the difference between the color value of the pigment and the reference coordinate value of the mortar. This study designed a gradient dosing experiment for six pigments: white, red, green, yellow, and blue pigments at 0–12%, and black at 0–3%. The influence of pigment type and dosage on the color parameters of MPC mortar was analyzed, a linear repair color matching model under the influence of a single pigment was obtained, and a color coefficient matrix was proposed. and correction coefficient matrix Establish a linear model to solve for pigment dosage. This led to the establishment of a color-matching matrix applicable to the calculation of various pigment dosages, enabling color control in any concrete repair project. Ultimately, a color compatibility repair method was established, combining quantitative detection, dynamic color control, and long-term durability observation.

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