Composite liquid retarder and preparation method thereof

Abstract

The application discloses a composite liquid retarder and a preparation method thereof. The composite liquid retarder is a novel phosphate modified super-retarder prepared by using an organic compound as a main component through a special process. The composite liquid retarder not only has the surface activity effect of an ordinary retarder, but also can form stable complex compounds with various metal ions due to the unique molecular structure, especially forms a stable six-ring chelate compound with calcium ions generated in the hydration of cement, has excellent retarding effect, and is suitable for compounding liquid concrete admixtures with long-time retarding effect and various concrete projects with retarding requirements.

Description

Technical Field

[0001] This invention relates to the field of concrete additives, and in particular to a composite liquid retarder and its preparation method. Background Technology

[0002] Retarder is a key component in polycarboxylate superplasticizer systems, and its performance requirements are increasingly stringent. Retarder, retarded superplasticizer, high-efficiency retarded superplasticizer, and high-performance retarded superplasticizer are widely applicable to mass concrete, roller-compacted concrete, concrete constructed in high-temperature environments, large-area poured concrete, concrete with cold joint prevention, and concrete in various engineering scenarios requiring delayed setting time, such as those involving long-term storage or long-distance transportation, self-leveling without vibration, slipform construction, and pull-form construction.

[0003] Currently, commercially available retarders are mainly traditional sugar-based, hydroxy acid-based, and inorganic salt-based products, often used in combination with water-reducing agents. They have solved many practical problems in engineering projects, have a wide range of applications, and have gained market recognition. However, with the continuous upgrading of engineering requirements, existing conventional retarders are no longer sufficient to meet the requirements of ultra-retarded concrete. Therefore, it is necessary to develop liquid ultra-retarders with better retarding effects and more stable performance to replace existing products. Summary of the Invention

[0004] This invention discloses a composite liquid retarder and its preparation method, which has low water reduction rate and low slump, and can effectively solve the above problems.

[0005] To achieve the above-mentioned technical effects, the present invention employs the following technology: a composite liquid retarder, wherein the retarder comprises the following raw materials in parts by weight: Tap water: 25-55; Hydroxyethylidene diphosphonic acid: 8–24; Aminotrimethylenephosphonic acid: 2-20; Sodium dihydrogen phosphate: 2-30; Glucose: 3-15.

[0006] During preparation, water is first added to the bottom of the vessel; then hydroxyethylidene diphosphonic acid and aminotrimethylene phosphonic acid are added sequentially according to their mass fractions, and the water bath is heated to 55°C and maintained at that temperature. Then add glucose and sodium dihydrogen phosphate in the correct weight proportions, and continue heating until all glucose and sodium dihydrogen phosphate are completely dissolved and there are no particles. Then raise the temperature to 55°C and maintain that temperature. Finally, stop heating and maintain the temperature at 55 degrees Celsius, stirring continuously for 30 minutes to obtain a transparent liquid and a composite liquid retarder.

[0007] Compared with existing technologies, this invention significantly extends the initial and final setting times of concrete, meeting the needs of ultra-retarded setting projects, and its retarding effect is superior to conventional retarders such as sodium gluconate. It also possesses surface activity, improving the fluidity of the cement paste, exhibiting strong slump retention, and maintaining good workability even after prolonged storage. Furthermore, it has strong compatibility and can be directly used in admixture formulations. Finally, this invention relates to the product and its process, which is prepared at room temperature and pressure, produces no waste, has low energy consumption, and is highly efficient. Detailed Implementation

[0008] To make it easier for those skilled in the art to understand, further explanation is provided below with reference to specific embodiments.

[0009] A composite liquid retarder, wherein the raw material ratio of the composite liquid retarder is as follows, by weight: Tap water: 25-55; Hydroxyethylidene diphosphonic acid: 8–24; Aminotrimethylenephosphonic acid: 2-20; Sodium dihydrogen phosphate: 2-30; Glucose: 3-15.

[0010] Example 1: First, add 55g of water to the bottom of the vessel, then add 10g of hydroxyethylidene diphosphonic acid and 10g of aminotrimethylene phosphonic acid in sequence. Heat in a water bath to 55℃, then add 5g of glucose and 20g of sodium dihydrogen phosphate in sequence. Continue heating until the glucose and sodium dihydrogen phosphate are completely dissolved. Raise the temperature back to 55℃ and maintain it, stirring continuously for 30 minutes to obtain the composite liquid retarder.

[0011] Example 2: First, add 25g of water to the bottom of the vessel, then add 20g of hydroxyethylidene diphosphonic acid and 20g of aminotrimethylene phosphonic acid in sequence. Heat in a water bath to 55℃, then add 5g of glucose and 30g of sodium dihydrogen phosphate in sequence. Continue heating until the glucose and sodium dihydrogen phosphate are completely dissolved. Raise the temperature back to 55℃ and maintain it, stirring continuously for 30 minutes to obtain the composite liquid retarder.

[0012] Example 3: First, add 30g of water to the bottom of the vessel, then add 10g of hydroxyethylidene diphosphonic acid and 20g of aminotrimethylene phosphonic acid in sequence. Heat in a water bath to 55℃, then add 10g of glucose and 30g of sodium dihydrogen phosphate in sequence. Continue heating until the glucose and sodium dihydrogen phosphate are completely dissolved. Raise the temperature back to 55℃ and maintain it, stirring continuously for 30 minutes to obtain the composite liquid retarder.

[0013] Example 4: First, add 40g of water to the bottom of the vessel, then add 20g of hydroxyethylidene diphosphonic acid and 10g of aminotrimethylene phosphonic acid in sequence. Heat in a water bath to 55℃, then add 10g of glucose and 20g of sodium dihydrogen phosphate in sequence. Continue heating until the glucose and sodium dihydrogen phosphate are completely dissolved. Raise the temperature back to 55℃ and maintain it, stirring continuously for 30 minutes to obtain the composite liquid retarder.

[0014] After preparation, comparative tests were conducted. All data on the fluidity of the cement paste were measured according to the GB8077-2012 standard "Test Method for Homogeneity of Concrete Admixtures". The data on the initial slump, spread and retention value, setting time, and strength of the concrete mixture were measured according to the GB8076-2008 standard "Concrete Admixtures". The specific results are shown in Table 1 and Table 2.

[0015]

[0016] Table 1. Comparison of Cement Paste with Various Retarder Agents

[0017] Table 2. Comparison of concrete with different retarder assemblies The comparison of the above data on the fluidity of the cement paste, the setting time of the cement, and the performance of the concrete shows that this product has a longer retarding time than both sodium gluconate and the blank sample, and exhibits better initial water reduction rate, slump retention, and workability. Its overall performance is superior to that of sodium gluconate.

[0018] In summary, this composite liquid retarder is a novel phosphate-modified super-retarder made primarily of organic compounds using a special process. It not only possesses the surface-active properties of ordinary retarders, but its unique molecular structure also allows it to form stable complexes with various metal ions, especially with calcium ions produced during cement hydration, forming stable hexagonal chelates. This results in excellent retarding effects, making it suitable for compounding with long-term retarding liquid concrete admixtures and various concrete projects requiring retarding. Hydroxyethylidene diphosphonic acid (HEDTA) can form stable complexes with metal ions, exhibiting good scale inhibition and a significant solubility limit effect. When used in combination with other water treatment agents, it demonstrates an ideal synergistic effect, improving the water-reducing rate of the retarder and effectively extending the setting time. Sodium dihydrogen phosphate introduces sodium ions into the retarder, reacting with HEDTA and aminotrimethylene phosphonic acid to significantly enhance corrosion inhibition. Simultaneously, sodium dihydrogen phosphate also introduces phosphate and hydrogen ions, both contributing to extending the setting time of concrete. Glucose exhibits strong activity on the surfaces of cement particles and new phases of hydration products, adsorbing onto the surface of solid particles and delaying the formation of cement and slurry structures. Glucose adsorbs onto the C3S surface to form an adsorption film, hindering the cement hydration process. The production process is simple, effectively improving production efficiency; no waste is generated during the entire process, making it environmentally friendly.

Claims

1. A composite liquid retarder, characterized in that, The retarder comprises the following raw materials in parts by weight: Tap water: 25-55; Hydroxyethylidene diphosphonic acid: 8–24; Aminotrimethylenephosphonic acid: 2-20; Sodium dihydrogen phosphate: 2-30; Glucose: 3-15.

2. A method for preparing the composite liquid retarder as described in claim 1, characterized in that, Includes the following steps: First, add tap water to the bottom of the pot according to the weight percentage; Then, add hydroxyethylidene diphosphonic acid and aminotrimethylene phosphonic acid in sequence according to their weight proportions, heat in a water bath to 55°C, and then maintain this temperature. Then add glucose and sodium dihydrogen phosphate in the correct weight proportions, and continue heating until all glucose and sodium dihydrogen phosphate are completely dissolved and there are no particles. Then raise the temperature to 55°C and maintain that temperature. Finally, stop heating and maintain the temperature at 55 degrees Celsius, stirring continuously for 30 minutes to obtain a transparent liquid and a composite liquid retarder.

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