Concrete admixtures are now having an increasing impact on production. The so-called concrete accelerating admixture is a gray powdery product that is modified and prepared from a variety of ingredients such as alumina, soda ash, and thickeners. In cement construction, it has the effect of fast setting hardness and early strength and water reduction of cement. It is also relatively widely used in practical applications. The cement slurry mixed with an appropriate amount of this product can quickly set and harden, and has high early strength. And it can maintain other properties of cement, making it an ideal concrete and mortar project in my country.
1. Concrete accelerating setting agent is mainly suitable for sprayed concrete construction and leakage prevention and plugging in highways, railways, bridges, mines, tunnels, tunnels, national defense, water conservancy and other projects, rapid ground concrete construction and concrete emergency Rescue project.
2. The dosage of concrete accelerating setting agent is 3-5%
3. Technical indicators of concrete accelerating setting agent:
1. The fineness (%) is less than 12.6
2. Setting time: initial setting (min) 2-3; final setting (min) 8-10
3. Moisture content (%) is less than 2
4. ld compressive strength (Mpa) is greater than or equal to 8
5. 28d compressive strength ratio (%) (Mpa) is greater than or equal to 75
IV. Rapid setting of concrete How to use the agent and precautions
1. Before use, it is necessary to conduct a suitability test on the cement used in construction to determine the optimal dosage.
2. During construction, the water-cement ratio should be strictly controlled between 0.40-0.45. If the water-cement ratio is too large, it will prolong the setting time and affect the use effect.
3. When used in shotcrete construction, sand, gravel, cement and quick-setting agent should be dry mixed in proportion to form a mixture, adjust the water-cement ratio, and spray immediately. The dry mix should be stacked for too long (more than 20 minutes). Otherwise, the quick-setting effect will be affected and the strength of shotcrete will be reduced.
4. When the construction conditions are poor or the adaptability of cement and this agent is poor, it is necessary to test to determine or increase the dosage appropriately.
Concrete accelerating setting agent formula
1. Hongxing Type 1 accelerating setting agent is composed of alumina clinker (the main component is sodium aluminate), sodium carbonate and quicklime according to mass 1: A powder prepared with a ratio of 1:0.5. The appropriate dosage is 2.5% to 4.0% of the cement mass.
2. 7ll type accelerating setting agent is made by grinding alumina clinker and anhydrous gypsum in a mass ratio of 3:1. The appropriate dosage is 3% to 5% of the cement mass.
3. Type 782 accelerating setting agent is prepared from alum mud, alumina clinker and quicklime in a mass ratio of r, 4.5%: 14.5%: 11%. The appropriate dosage is 5% to 7%.
4. Several other accelerating setting agents also use aluminum-oxygen clinker as the main component.
Accelerating admixture is an admixture that can quickly set and harden concrete. The main types of accelerators are inorganic salts and organic substances. The commonly used accelerating setting agents in my country are inorganic salts.
Inorganic salt accelerating setting agents can be roughly divided into three categories according to their main components:
1. Accelerating setting agents with sodium aluminate as the main component;
2. Accelerating setting agents with calcium aluminate, calcium fluoroaluminate, etc. as the main component;
3. Accelerating setting agents with silicate (NaSiO2) as the main component.
The formula of concrete accelerator is what we are talking about. I hope it will be helpful to you.
2. Preparation method of polycarboxylic acid superplasticizer:
Add water and initiator to the reactor, and then slowly drop in water containing sodium allyl sulfonate, poly Mix the solution of oxyethylene ether methacrylate and methacrylic acid, stir and heat to 80-120 degrees Celsius, react for 4-6 hours and after the reaction is completed, add it to the connecting tube, continue to keep warm and stir for 1-2 hours to discharge, and you will get Polycarboxylic acid high performance water reducing agent. Raw Material Compatibility The mass ratio range of each component of this product is: the mass ratio of sodium allyl sulfonate, polyoxyethylene ether methacrylate, and methacrylic acid in the mixed solution is 1: 8: (1-2). The described initiator is persulfate, and the dosage is 0.1%-1% of the mass of the mixed solution. The described continuous transfer agent is lauryl alcohol, and the dosage is 0.1%-1% of the mass of the mixed solution. %. Product Application This product is mainly used as a water-reducing agent, which can replace cement with more slag or fly ash, thereby reducing costs.
What are the raw materials for the synthesis of polycarboxylate superplasticizer?
Materials: acrylic acid (AA), sodium methacrylate sulfonate (MAS), ammonium persulfate (APS), Synthesis method of polyoxyethylene allyl ester macromonomer: Prepare acrylic acid, sodium methacrylate sulfonate, ammonium persulfate, and polyoxyethylene allyl ester macromonomer with deionized water to form an aqueous solution with a concentration of 20%. . Add the monomer and initiator in batches into a three-necked flask equipped with a stirrer, reflux condenser and thermometer. After the addition is completed, keep the reaction at 75°C for a certain period of time
Characteristics of the product:
(1) In the process of product application, it can exert high dispersion performance at low output (0.2%-0.5%).
(2) Polycarboxylic acid can maintain good slump retention, and there is basically no loss of slump within 90 minutes.
(3) When comparing concrete with the same fluidity during application, the delayed setting time is less,
(4) The degree of freedom in the molecular structure is large, and the production of admixtures is There are many technically controllable parameters and great potential for high performance.
(5) Since the harmful substances in polycarboxylic acid are low, it does not cause pollution to the environment.
(6) Good compatibility with cement and other types of concrete admixtures.
Polycarboxylate water-reducing agent refers to the ability to reduce the amount of mixing water while maintaining the workability of concrete and the amount of cement., improve the strength of concrete; or save the amount of cement while maintaining workability and strength.
According to its water-reducing and strengthening capabilities, it is divided into ordinary water-reducing agents (also known as plasticizers) and high-efficiency water-reducing agents (also known as superplasticizers). According to the composition materials, they are divided into: (1) water-based sulfonates; (2) polycyclic aromatic salts; (3) water-soluble resin sulfonates.
Ordinary water reducing agents should be used for concrete construction where the daily minimum temperature is above 5℃. High-efficiency water-reducing admixtures are suitable for concrete construction where the daily minimum temperature is above 0°C, and are suitable for preparing high-fluidity concrete, high-strength concrete and steam-cured concrete.
Several types of water-reducing agents commonly used in the market are: naphthalene-based high-efficiency water-reducing agent, aliphatic high-efficiency water-reducing agent, amino super-speed high-performance water-reducing agent, water-reducing activator, and general sugar acid. Sodium, sodium lignosulfonate, lignosulfonate, swelling agent, etc.
The preparation method of polycarboxylate water-reducing agent is based on the above points. I hope it will be helpful to you.
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