Cement retarder as well as preparation method and application thereof
The cement retarder is prepared by mixing citric acid, caster sugar and water, and spraying it at a 45° angle below the cement preparation chute. This solves the problem of difficult-to-control cement final setting time and achieves low-cost compliance with construction standards.
Patent Information
- Application Number
- CN202510684554.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-26
- Publication Date
- 2025-09-19
AI Technical Summary
Commercially available cement retarders are expensive and difficult to effectively control the final setting time of slag silicate cement, which easily exceeds national standards and results in construction that does not meet standards.
Citric acid, caster sugar and water are mixed in a specific proportion to form a cement retarder, which is then sprayed at a 45° angle below the cement preparation chute through a spray device to increase the contact area with the powdered material and delay the hydration reaction.
The final setting time of slag silicate cement can be controlled in a simple and low-cost manner to ensure that the construction meets the standards.
Smart Images
Figure SMS_1 
Figure SMS_2
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of cement additive production, in particular to a cement retarder, a preparation method and application thereof. Background Art
[0002] Cement, as an important cementing material, is widely used in civil engineering, water conservancy, national defense and other projects.
[0003] Cement is divided into general-purpose cement and special cement according to its use and performance. Compared with the general-purpose cement used in general civil construction projects, special cement refers to cement with certain unique properties and is suitable for specific uses, such as G-grade oil well cement, fast-hardening Portland cement, road Portland cement, aluminate cement, sulphoaluminate cement, etc.
[0004] In highway construction, due to the long construction process, based on the on-site construction conditions, the initial setting time of cement is required to be around 6 hours and the final setting time is around 9 hours. The initial setting time of slag Portland cement is 2.5-4 hours, and the final setting time is 4.5-6.5 hours, which complies with the provisions of GB 175-2023 "General Portland Cement" that the initial setting time of slag Portland cement should be no less than 45 minutes and the final setting time should be no more than 600 minutes. In actual construction, in order to control the final setting time of cement, it is necessary to add cement retarders. However, the price of commercially available cement retarders is relatively high, and the final setting time of slag Portland cement with retarder is difficult to control within 9 hours, which is easy to exceed the national standard requirement that the final setting time should be no more than 600 minutes, resulting in the cement not meeting the construction standards after construction. Summary of the Invention
[0005] The embodiments of the present application provide a cement retarder, a preparation method and an application thereof, to solve the problem that the final setting time of Portland cement is difficult to control.
[0006] The embodiment of the present application provides a method for preparing a cement retarder, comprising the following steps: mixing citric acid, granulated sugar, and water in a volume ratio of 5-25% citric acid, 5-25% granulated sugar, and 50-90% water to obtain a cement retarder.
[0007] Preferably, the citric acid comprises 5-15%, the granulated sugar comprises 15-25%, and the water comprises 60-70%.
[0008] Preferably, the citric acid comprises 15%, granulated sugar comprises 15%, and water comprises 70%.
[0009] The present invention also provides a cement retarder prepared by the above preparation method.
[0010] The present invention also provides a method for using the cement retarder described above, comprising the following steps: uniformly mixing the cement retarder with ground cement clinker to obtain treated cement; wherein the cement retarder content in each ton of the treated cement is 0.5-1.5‰.
[0011] Preferably, the cement retarder is mixed with the ground cement clinker, and the content of the cement retarder is 1‰ per ton of the treated cement.
[0012] Preferably, the cement retarder is sprayed into the cement preparation chute at an angle of 45° to the cement flow direction through two spray devices arranged below the cement preparation chute.
[0013] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages: the preparation method provided by the present invention is simple to operate and low in cost, and the obtained cement retarder can effectively control the final setting time of slag silicate cement. DETAILED DESCRIPTION
[0014] The embodiments of the present application provide a cement retarder, a preparation method and an application thereof, to solve the problem that the final setting time of Portland cement is difficult to control.
[0015] The technical solution in the embodiments of the present application is to solve the problem of the difficulty in controlling the final setting time. The overall concept is as follows: a cement retarder is provided, and citric acid, granulated sugar, and water are mixed in a volume ratio of 5-25% citric acid, 5-25% granulated sugar, and 50-90% water, and more specifically, 5-15% citric acid, 15-25% granulated sugar, and 60-70% water to obtain the cement retarder; the cement retarder is sprayed into the cement preparation chute at a 45° angle to the cement flow direction through two spray devices arranged below the cement preparation chute to obtain treated cement.
[0016] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with specific implementation methods. Example 1
[0017] The embodiment of the present application provides a method for preparing a cement retarder, comprising the following steps: mixing citric acid, granulated sugar, and water in a volume ratio of 5-25% citric acid, 5-25% granulated sugar, and 50-90% water to obtain a cement retarder.
[0018] Citric acid reacts with aluminate, more specifically, with tricalcium aluminate to form a low-solubility aluminum citrate complex, thereby slowing down the hydration process of aluminate and achieving the effect of delaying cement setting; Granulated sugar can be adsorbed on the surface of cement particles to form a thin sugar film. This sugar film can prevent water molecules from directly contacting the cement particles, thereby slowing down the hydration process of the cement particles. As the hydration reaction rate decreases, the initial and final setting times of the cement will be extended accordingly.
[0019] The technical solutions in the above-mentioned embodiments of the present application have at least the following technical effects or advantages: the preparation method provided by the present invention is simple to operate and low in cost, and the obtained cement retarder can effectively control the final setting time of slag silicate cement. Example 2
[0020] The embodiment of the present application provides a method for preparing a cement retarder, comprising the following steps: mixing citric acid, granulated sugar, and water in a volume ratio of 5-25% citric acid, 5-25% granulated sugar, and 50-90% water to obtain a cement retarder.
[0021] Using the same type of cement as the benchmark sample, by adjusting the ratio of citric acid, granulated sugar, and water in the retarder components, as shown in Table 1, the optimal volume ratio of the retarder is 5-15% citric acid, 15-25% granulated sugar, and 60-70% water; more preferably, the citric acid is 15%, the granulated sugar is 15%, and the water is 70%.
[0022] Table 1 Citric acid granulated sugar water Initial setting time (min) Final setting time (min) 3-day compressive strength Experiment A 15-25% 5-15% 70% 270 390 22.9 Experiment B 5-15% 15-25% 70% 340 532 23.1 Experiment C 15% 15% 70% 336 589 23.4 In addition, the most preferred volume ratio of cement retarder is 15% citric acid, 15% granulated sugar and 70% water, which effectively solves the problem that improper use of sugar retarders may cause the 28-day strength of concrete to decrease by 5%-15%.
[0023] Example 3 An embodiment of the present application provides a method for using the cement retarder described above, comprising the following steps: uniformly mixing the cement retarder with ground cement clinker to obtain treated cement; wherein the cement retarder content per ton of the treated cement is 0.5-1.5‰.
[0024] More preferably, the cement retarder is mixed with the ground cement clinker to obtain treated cement, and by adjusting the ratio of cement retarder to cement base sample, as shown in Table 2, the content of the cement retarder in each ton of the treated cement is 1‰.
[0025] Table 2 Cement retarder content Initial setting time (min) Final setting time (min) 3-day compressive strength Cement-based samples 0 233 315 26.4 Experiment A 0.5‰ 255 355 26.0 Experiment b 1‰ 395 553 26.1 Experiment c 1.5‰ 426 595 26.3 Example 4 The present embodiment provides a method for using the cement retarder described above. The cement retarder is sprayed into the cement preparation chute at a 45° angle to the cement flow direction through two spray devices arranged below the cement preparation chute, thereby increasing the contact area between the retarder and the powdered material, so that the liquid retarder can better wrap the powdered material. The test was successful, as shown in Table 3.
[0026] Table 3
[0027] Citric acid molecules can adsorb on the surface of cement particles, change the charge state of cement particles, increase the electrostatic repulsion between particles, prevent cement particles from prematurely aggregating, and thus slow down the rate of hydration reaction; citric acid can also affect the formation process of cement hydration products; for example, it can inhibit the growth of calcium hydroxide (Ca(OH)2) crystals and slow down the hardening rate of cement stone structure.
[0028] When cement is added with water and stirred, caster sugar dissolves in water and increases the viscosity of the aqueous solution. The high viscosity solution can reduce the diffusion rate of water molecules to the surface of cement particles, thereby slowing down the hydration reaction. This effect helps to prolong the setting time of cement.
[0029] In the early stages of cement hydration, certain key ions (such as Ca²⁺) are crucial for the hydration reaction. Granulated sugar molecules may competitively adsorb with these ions, reducing their effective contact opportunities with cement particles, thereby indirectly slowing down the hydration reaction and increasing the cement setting time.
[0030] In comparison, the spray device is set above the cement preparation chute, and the direction of adding the cement retarder is perpendicular to the cement flow direction. After verification by experimental data, the expected retarding effect is not achieved. As shown in Table 4, after testing the cement retarder used, there is no problem with the cement retarder.
[0031] Table 4
[0032] It should be noted that the spray device can be a commercially available nozzle that sprays using a high-pressure pump, with dual metering using a flow meter and a hanging scale to ensure the accurate addition of the cement retarder. Two spray devices are used to ensure uniformity during the incorporation of the liquid cement retarder into the cement. The aforementioned equipment or devices are all prior art and will not be described in detail here.
[0033] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.
[0034] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include these modifications and variations.
Claims
1. A method for preparing a cement retarder, comprising the following steps: Mix citric acid, granulated sugar and water in a volume ratio of 5-25% citric acid, 5-25% granulated sugar and 50-90% water to obtain a cement retarder.
2. The preparation method according to claim 1, characterized in that The citric acid is 5-15%, the soft sugar is 15-25%, and the water is 60-70%.
3. The preparation method according to claim 1, characterized in that The composition comprises 15% citric acid, 15% granulated sugar and 70% water.
4. A cement retarder prepared by the preparation method according to any one of claims 1 to 3.
5. The method for using the cement retarder according to claim 4, comprising the following steps: The cement retarder is evenly mixed with the ground cement clinker to obtain treated cement; the content of the cement retarder in each ton of the treated cement is 0.5-1.5‰.
6. The method of use according to claim 5, characterized in that: The cement retarder is mixed with the ground cement clinker, and the content of the cement retarder in each ton of the treated cement is 1‰.
7. The method of use according to claim 6, characterized in that: The cement retarder is sprayed into the cement preparation chute at an angle of 45° to the cement flow direction through two spray devices arranged below the cement preparation chute.