Silicate-based waterproofing coating material, mortar composition, hardened mortar body, and waterproofing method

Abstract

To provide a silicate-based waterproof coating material that enables a large amount of acicular or filamentous crystal of calcium silicate hydrate to be formed inside concrete.SOLUTION: A silicate-based waterproof coating material contains cement and a crystallization promoter. The crystallization promoter is crystal powder of calcium silicate hydrate.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a silicate-based waterproof coating material, a mortar composition, a hardened mortar body, and a waterproofing method. [Background technology]

[0002] In recent years, various waterproofing methods have been developed to waterproof concrete in underground structures such as exterior walls and floors, water tanks, and pits. Silicate-based waterproofing materials are used in these methods due to their ease of application. Silicate-based waterproofing materials are applied to the surface of concrete structures, densifying the surface layer and providing waterproofing against water permeability. These materials are powders composed of cement, silicate powder, etc., and are used by mixing them with a specified amount of water, or water and polymer dispersion. Silicate-based waterproofing materials are known for their low incidence of blistering and peeling, even when applied to substrates subjected to backwater pressure.

[0003] For example, Patent Document 1 discloses a concrete surface modifier as a silicate-based waterproof coating material, comprising succinic acid, sodium carbonate, magnesium hydroxide, powdered sodium silicate, Portland cement, finely powdered silica, carboxylic acid, and Sealdex. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2004-332325 [Overview of the project] [Problems that the invention aims to solve]

[0005] The necessary properties of silicate-based waterproof coatings include ease of application and water permeability resistance, with water permeability resistance being particularly important from the perspective of waterproofing performance. Water permeability resistance is thought to be imparted by the reaction of silicate ions leached from the silicate-based waterproof coating with calcium ions inside the concrete, which generate needle-shaped or fibrous crystalline calcium silicate hydrate that fills the capillary voids in the concrete, thereby promoting densification of the concrete surface. However, depending on the usage environment, the leaching of silicate ions may be insufficient, resulting in inadequate formation of needle-shaped or fibrous crystalline calcium silicate hydrate.

[0006] Therefore, the main objective of the present invention is to provide a silicate-based waterproof coating material that can generate a large amount of needle-shaped or fibrous crystals of calcium silicate hydrate inside concrete. [Means for solving the problem]

[0007] As a result of diligent research by the inventors to solve the above problems, they discovered that crystalline powder of calcium silicate hydrate acts as a crystal growth agent capable of generating a large amount of needle-shaped or fibrous crystals of calcium silicate hydrate inside concrete, thus completing the present invention.

[0008] One aspect of the present invention relates to a silicate-based waterproof coating material. This silicate-based waterproof coating material contains cement and a crystal growth agent. The crystal growth agent is a crystalline powder of calcium silicate hydrate. With such a silicate-based waterproof coating material, it is possible to generate a large amount of needle-shaped or fibrous crystals of calcium silicate hydrate inside the concrete. The reason for this effect is thought to be that the crystalline powder of calcium silicate hydrate acts as a so-called seed crystal, promoting the crystal formation of calcium silicate hydrate. By generating a large amount of needle-shaped or fibrous crystals of calcium silicate hydrate, the surface layer of the concrete structure becomes denser, and the concrete structure can be given excellent waterproofing properties.

[0009] The content of the crystal growth agent may be 0.03 to 5.5 parts by mass per 100 parts by mass of cement.

[0010] The silicate-based waterproof coating material may further contain silicate powder.

[0011] Another aspect of the present invention relates to a mortar composition, which contains the above-mentioned silicate-based waterproof coating material and water.

[0012] Another aspect of the present invention relates to a hardened mortar body, which contains a hardened product of the above-mentioned mortar composition.

[0013] Another aspect of the present invention relates to a waterproofing method. This waterproofing method comprises the steps of applying the above-mentioned mortar composition to the surface of concrete and hardening the applied mortar composition. [Effects of the Invention]

[0014] The present invention provides a silicate-based waterproof coating material capable of generating a large amount of needle-shaped or fibrous crystals of calcium silicate hydrate within concrete. Furthermore, the present invention provides a mortar composition using such a silicate-based waterproof coating material. Moreover, the present invention provides a hardened mortar and a waterproofing method using such a mortar composition. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 shows an example of a test specimen captured by a scanning electron microscope, with Figures 1(a), 1(b), and 1(c) showing images with different proportions of needle-shaped or fibrous crystals. [Modes for carrying out the invention]

[0016] Embodiments of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments.

[0017] In this specification, unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more within the applicable range of conditions. When there are a plurality of substances corresponding to each component, unless otherwise specified, the content of each component means the total amount of the plurality of substances.

[0018] [Silicate-based coating waterproof material] The silicate-based coating waterproof material of one embodiment contains cement and a crystal growth agent. The silicate-based coating waterproof material may further contain silicate powder. The silicate-based coating waterproof material may contain other components. The silicate-based coating waterproof material can be a hydraulic composition.

[0019] (Cement) Examples of the cement include ordinary Portland cement, early-strength Portland cement, ultra-early-strength Portland cement, medium-heat Portland cement, low-heat Portland cement, sulfate-resistant cement, white cement, blended cement, alumina cement, and the like. Among these, the cement may be, for example, ordinary Portland cement.

[0020] The content of the cement may be 20 to 60% by mass based on the total amount of the silicate-based coating waterproof material. When the content of the cement is 20% by mass or more based on the total amount of the silicate-based coating waterproof material, it tends to be possible to work without blurring, and when it is 60% by mass or less, it can prevent the decrease in fluidity due to the rapid reaction of the crystal growth agent and tends to have excellent workability. The content of the cement may be 25% by mass or more or 30% by mass or more based on the total amount of the silicate-based coating waterproof material, and may be 55% by mass or less or 50% by mass or less.

[0021] (Crystal growth agent) The crystal growth agent is a hydrated calcium silicate crystal powder. As a crystal growth agent, a siliceous coating waterproofing material containing a hydrated calcium silicate crystal powder can generate a large amount of acicular or fibrous crystals of hydrated calcium silicate inside concrete. The reason for such an effect is considered to be that the hydrated calcium silicate crystal powder acts as a so-called seed crystal and promotes the crystal formation of hydrated calcium silicate. The generation of a large amount of acicular or fibrous crystals of hydrated calcium silicate progresses the densification of the surface layer of the concrete structure, and excellent waterproof properties can be imparted to the concrete structure.

[0022] The BET specific surface area of the hydrated calcium silicate crystal powder may be 0.5 to 10 m 2 / g. When the BET specific surface area is 0.5 m 2 / g or more, a large amount of acicular or fibrous crystals of hydrated calcium silicate are likely to be generated, and the effect of water permeability resistance is likely to be sufficiently obtained. When it is 10 m 2 / g or less, it is possible to prevent the decrease in fluidity due to the rapid reaction of the crystal growth agent, and the workability tends to be excellent. The BET specific surface area may be 0.8 m 2 / g or more, 1.1 m 2 / g or more, or 1.4 m 2 / g or more, and may also be 9 m 2 / g or less, 8 m 2 / g or less, or 7 m 2 / g or less. The BET specific surface area can be measured with a BET specific surface area meter by the nitrogen adsorption method.

[0023] The content of the crystal growth agent may be 0.03 to 5.5 parts by mass per 100 parts by mass of cement. When the content of the crystal growth agent is 0.03 parts by mass or more per 100 parts by mass of cement, needle-shaped or fibrous crystals of calcium silicate hydrate tend to be easily formed in large quantities, and the effect of water permeability resistance tends to be easily obtained. When the content of the crystal growth agent is 5.5 parts by mass or less per 100 parts by mass of cement, the decrease in fluidity due to the rapid reaction of the crystal growth agent can be prevented, and the workability tends to be excellent. The content of the crystal growth agent may be 0.05 parts by mass or more, 0.1 parts by mass or more, 0.3 parts by mass or more, 0.5 parts by mass or more, or 0.7 parts by mass or more per 100 parts by mass of cement, and may also be 5.0 parts by mass or less, 4.8 parts by mass or less, 4.5 parts by mass or less, 4.2 parts by mass or less, or 4.0 parts by mass or less.

[0024] (Silicate powder) The silicate-based waterproof coating material may further contain silicate powder (excluding crystalline powder of calcium silicate hydrate). The inclusion of silicate powder in the silicate-based waterproof coating material allows for a more satisfactory balance between water permeability and workability.

[0025] The silicate powder may be, for example, an alkali silicate. Examples of alkali silicates include sodium silicate and potassium silicate. The silicate powder may also be at least one selected from the group consisting of, for example, sodium silicate and potassium silicate.

[0026] The content of silicate powder is not particularly limited, but may be 1 to 40 parts by mass per 100 parts by mass of cement. The content of silicate powder may be 2 parts by mass or more, 3 parts by mass or more, or 5 parts by mass or more per 100 parts by mass of cement, and may be 30 parts by mass or less, 20 parts by mass or less, 15 parts by mass or less, or 10 parts by mass or less.

[0027] (Other ingredients) The silicate-based waterproof coating material may further contain other components, to the extent that it does not impair the effects of the present invention. Examples of other components include aggregates such as sand, crescent stone, and pyrophyllite; expansive agents; hardening agents; water-reducing agents; defoaming agents; thickeners; rust inhibitors; shrinkage-reducing agents; water-retaining agents; fibers; resin powders; clay minerals such as attapulgite; and admixtures such as blast furnace slag powder, limestone powder, fly ash, and silica fume. These other components may be used individually or in combination of two or more.

[0028] The content of other components is not particularly limited, but may be 50 to 400 parts by mass per 100 parts by mass of cement. The content of other components may be 80 parts by mass or more, or 100 parts by mass or more, or 300 parts by mass or less, or 250 parts by mass or less, per 100 parts by mass of cement.

[0029] The silicate-based waterproof coating material of this embodiment makes it possible to generate a large amount of needle-shaped or fibrous crystals of calcium silicate hydrate within the concrete. The silicate-based waterproof coating material of this embodiment is used, for example, after being mixed with water to prepare a mortar composition.

[0030] [Mortar composition] The mortar composition of one embodiment can be prepared by mixing water with the above-mentioned silicate-based waterproof coating material. That is, the mortar composition of this embodiment contains the above-mentioned silicate-based waterproof coating material and water.

[0031] The water content may be 20 to 50 parts by mass per 100 parts by mass of the silicate-based waterproof coating material. The water content may be 25 parts by mass or more, or 30 parts by mass or more, and may also be 45 parts by mass or less, or 40 parts by mass or less, per 100 parts by mass of the silicate-based waterproof coating material.

[0032] Mortar compositions are used by applying them to the surface of concrete using general methods such as rollers, trowels, and brushes. The applied mortar composition can be cured for 28 days at, for example, 20±2℃ in humid air with a humidity of 80%RH or higher to form a hardened mortar body (layer) containing the hardened mortar composition. From the viewpoint of waterproofing, it is preferable to apply and cure the mortar composition to the surface of concrete repeatedly to form multiple hardened mortar body layers containing the hardened mortar composition.

[0033] Examples of concrete to which the mortar composition is applied include the exterior walls and floors of underground structures, water tanks, pits, and the like.

[0034] [Hardened mortar] A hardened mortar body according to one embodiment can be obtained by hardening the above-described mortar composition. That is, the hardened mortar body of this embodiment contains a hardened product of the above-described mortar composition. The hardening conditions for the mortar composition may be the same as those described above.

[0035] [Waterproofing method] One embodiment of the waterproofing method comprises the steps of applying the above-mentioned mortar composition to the surface of concrete and hardening the applied mortar composition. The application method, the concrete to which the mortar composition is applied, the hardening conditions of the mortar composition, etc., may be the same as described above. [Examples]

[0036] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0037] [Materials used] (1) cement C: Ordinary Portland cement (manufactured by Ube Mitsubishi Cement Co., Ltd.: Blaine specific surface area 3300 cm²) 2 / g) (2) Crystal growth agent S: Calcium silicate hydrate crystalline powder (BET specific surface area: 2.4 m²)2 / g) (3) Silicate powder N: Sodium silicate (No. 3 anhydrous powder) (4) Other ingredients Aggregates, admixtures, water-reducing agents, defoaming agents, thickeners, etc.

[0038] [Preparation of silicate-based waterproof coating materials and mortar compositions] (Examples 1-8 and Comparative Example 1) Cement and crystal growth agent were mixed in the proportions shown in Table 1 (unit: parts by mass), and a total of 123 parts by mass of other components were added to 100 parts by mass of cement to prepare the silicate-based waterproof coating materials of Examples 1-8 and Comparative Example 1. 35 parts by mass of water were added to 100 parts by mass of the obtained silicate-based waterproof coating material to prepare the mortar compositions of Examples 1-8 and Comparative Example 1.

[0039] (Examples 9-14) Cement, a crystal growth agent, and a silicate powder were blended in the proportions shown in Table 2 (unit: parts by mass), and a total of 138 parts by mass of other components were added to 100 parts by mass of cement to prepare the silicate-based waterproof coating materials of Examples 9 to 14. 39 parts by mass of water were added to 100 parts by mass of the obtained silicate-based waterproof coating material to prepare the mortar compositions of Examples 9 to 14.

[0040] [Evaluation of silicate-based waterproof coating materials (mortar compositions)] (1) Evaluation of the amount of needle-shaped or fibrous crystals (Preparation of test specimens) In accordance with "JASS8 M-301-2014 Quality and Test Methods for Silicate-Based Waterproofing Coatings," ordinary Portland cement and Toyoura sand were used to create a mortar with a water / cement mass ratio of 0.65 and a sand / cement mass ratio of 2.3. This mortar was filled in two layers into a Φ150mm × 40mm mold, and finally, the mortar was raised to a height of approximately 5mm. Moisturized curing was then performed in a humid environment at 20°C and humidity of 80% RH or higher. Five hours after filling with mortar, the raised portion on top of the mold was carefully scraped off, taking care not to damage the specimen, and the top surface was smoothed by lightly stroking it without pressing. After 24 hours from the completion of filling the mold, the specimen was removed from the mold and further moistened for six days. After the above moist curing was completed, laitance and dirt were removed from the casting surface, and the casting surface was made moist. Subsequently, each mortar composition of Examples 1-14 and Comparative Example 1 was applied at a rate of 0.6 kg / m². 2 After application, confirm that the surface is completely dry after 3 hours, and then apply each mortar composition at 0.8 kg / m². 2 The sample was applied. Then, the specimens were cured for 28 days in humid air at 20±2℃ and humidity of 80%RH or higher to prepare the test specimens.

[0041] (Evaluation of needle-shaped or fibrous crystal content) Cross-sections of the obtained test specimens were cut out, and 40x magnified photographs were taken using a scanning electron microscope (JEOL Ltd., JSM-7000F). Next, the layer coated with the mortar composition was magnified 4000x, and 81 images were taken at 0.25mm intervals within a 2mm × 0.5mm area to investigate the amount of needle-like or fibrous crystals.

[0042] In the scanning electron microscope observation screen (magnification 4000x), points were assigned as follows: 3 points if the above crystals occupied 70% or more of the area, 2 points if they occupied 50% or more but less than 70%, 1 point if they occupied 30% or more but less than 50%, and 0 points if they occupied less than 30%. The total points for 81 screens were then summed to obtain the total score for the test specimen (coated test specimen) coated with silicate-based waterproof coating material. The scoring criteria were based on the example judgment in "JASS8 T-301 Review of Revision of Test Method for Silicate-Based Waterproof Coating Material, Building Materials Testing Information 5'14". The amount of needle-shaped or fibrous crystals was evaluated by calculating the ratio of the total score of coated specimens to the total score of uncoated specimens (total score of coated specimens / total score of uncoated specimens) based on the total score of the coated specimens obtained from the coated specimens and the total score of uncoated specimens obtained from the uncoated specimens. The results are shown in Tables 1 and 2.

[0043] Figure 1 shows an example of a test specimen captured by a scanning electron microscope, with Figures 1(a), 1(b), and 1(c) showing images with different proportions of needle-shaped or fibrous crystals. In Figure 1(a), crystals are present in the circled area. In Figure 1(a), the crystals occupy 20% of the observation area, and the result is judged as 0 points. In Figures 1(b) and 1(c), the crystals occupy 70% and 90% of the observation area, respectively, and both result in a score of 3 points.

[0044] (2) Calculation of the hydraulic conductivity ratio In accordance with "JASS8 M-301-2014 Quality and Test Methods for Silicate-Based Waterproofing Coatings," a Φ30 × 40 mm core was taken from the test specimen described in "(2) Evaluation of Needle-Shaped or Fibrous Crystal Content" above. After removing only the waterproofing material portion, the portion up to 5 mm from the coated surface was cut out to serve as a sample for measuring the water permeability coefficient. The sample for measuring the water permeability coefficient was attached to an output-type water permeability test apparatus, a water pressure of 0.294 MPa was applied, and after reaching a steady state, the amount of water flowing out per unit time was measured to calculate the water permeability coefficient. The water permeability coefficient was calculated using the Darcy formula shown below. Based on the calculated water permeability coefficient of the coated test specimen and the water permeability coefficient of the uncoated test specimen obtained from a test specimen without silicate-based waterproofing coating (uncoated test specimen), the ratio of the water permeability coefficient of the coated test specimen to the water permeability coefficient of the uncoated test specimen (water permeability coefficient ratio (water permeability coefficient of coated test specimen / water permeability coefficient of uncoated test specimen)) was calculated. The results are shown in Tables 1 and 2. K = (Q·p·l) / (P·A·t) K: Permeability coefficient (mm / s), Q: Amount of water discharged during time t (mm 3 ), p: density of water (kg / mm³) 3 ), l: sample thickness (mm), P: water pressure (MPa), A: cross-sectional area of ​​the sample (mm²) 3 ), t: time (s) (3) Workability Sensory evaluation was conducted when the mortar compositions of Examples 1-14 and Comparative Example 1 were applied using a plastering brush. A rating of "A" indicated good workability if the application was easy, "B" indicated a slightly heavy application, and "C" indicated a heavy application with streaking. The results are shown in Tables 1 and 2.

[0045] [Table 1]

[0046] As shown in Table 1, the silicate-based waterproof coating material in the example containing the crystal growth agent had a higher crystal content and, consequently, higher water permeability compared to the silicate-based waterproof coating material in the comparative example that did not contain the crystal growth agent. On the other hand, it was found that workability improved when the crystal growth agent content was 5.0 parts by mass or less per 100 parts by mass of cement.

[0047] [Table 2]

[0048] As shown in Table 2, the silicate-based waterproof coating material in the examples further containing silicate powder was found to achieve a higher level of balance between water permeability and workability.

[0049] From the above, it has been confirmed that the silicate-based waterproof coating material of the present invention is capable of generating a large amount of needle-shaped or fibrous crystals of calcium silicate hydrate inside concrete.

Claims

1. It contains cement, a crystal growth agent, and silicate powder. The cement is ordinary Portland cement. The crystal growth agent is a crystalline powder of calcium silicate hydrate. The content of the crystal growth agent is 0.5 to 2.0 parts by mass per 100 parts by mass of the cement. A silicate-based waterproof coating material wherein the siliceous powder is at least one selected from the group consisting of sodium silicate and potassium silicate.

2. A mortar composition containing the silicate-based waterproof coating material described in claim 1 and water.

3. A hardened mortar body containing a hardened product of the mortar composition described in claim 2.

4. A step of applying the mortar composition described in claim 2 to the surface of concrete, A step of hardening the applied mortar composition, A waterproofing method that includes the following features.

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