In recent years, with the advancement of science and technology and construction requirements, the concrete pouring method has changed from traditional hoisting construction to pipeline transportation, and the construction efficiency and construction quality have been greatly improved. When concrete is pumped for the first time, the slurry sticks to the inner wall of the pipe due to its own cohesiveness, affecting the quality and delivery of concrete. Therefore, most ready-mixed concrete is moistened with mortar with the same mortar to sand ratio before pumping, that is, at the beginning of concrete Before pumping, first use clean water to wet the pipeline, then transport the pump mortar with the same mortar to cement ratio and water to cement ratio as the concrete, and finally transport the concrete.
Although the traditional mortar pipe moistening method has been used for many years, it has obvious disadvantages, which are reflected in the following three aspects:
1. Part of the mortar is wasted and construction costs are increased;
2. In order to save vehicle costs, some ready-mixed concrete mixing stations generally use The mortar belt is used to transport pump mortar, that is, fresh concrete is placed at the bottom of the tank of the concrete transport truck, and the lubrication mortar is placed on the top of the tank. The tank should not be rotated during transportation. The purpose is to prevent the mixing of concrete and mortar, thereby It causes the slurry and aggregate in the concrete to separate and stratify, which ultimately affects the quality of the concrete and causes quality problems;
3. After using mortar to moisten the pump, excess mortar is easy to pour. into the prefabricated formwork, resulting in local strength substandard in the concrete structure and project quality problems.
Concrete pump truck lubricant
Composition and principle
Concrete pump truck lubricant is mainly composed of polymer materials, usually a white powdery solid. At room temperature, the lubricant can quickly dissolve in water to form a viscous liquid.
The main component of concrete pump truck lubricant is polyacrylamide, which is a water-soluble linear high molecular polymer polymerized from acrylamide monomer. The polymer molecules form bridge adsorption with the suspended particles dispersed in the solution, which has a strong flocculation effect. When the concentration is high, there are a large number of chain-to-chain contact points in the solution, making the polyacrylamide solution gel-like. This gel-like liquid is a lubricating film composed of countless micro-anions, which can fully lubricate the inner surface of the concrete pumping pipe.
Performance effect
Lubrication after the concrete pump truck lubricant forms a gel-like liquid The function is generally achieved through the following four aspects:
1. Reduce the adsorption of water on the pipe wall. The lubricating agent after adding water and mixing will become gel-like. , the gel-like liquid adheres to the inner wall of the pipe, preventing the pipe from absorbing moisture in the concrete and maintaining the fluid state of the concrete.
2. The low viscosity of the gel-like liquid reduces the viscous resistance of the pipe wall to the concrete.
3. As the concrete moves forward in the pumping pipe, the linear organic polymer compound chains of polyacrylamide stretch along the pipe wall and form a continuous and uniform layer. Lubricating film, concrete flows in the lubricating film.
4. The viscous resistance of the pumping pipeline is reduced, so the pump pressure becomes smaller, and the fresh concrete can be pumped smoothly.
Precautions for use
1. The lubricating agent should be dissolved in advance, and the solution should be sufficient at the same time. Soak and stir. The stirring time is about 5 minutes. The longer the stirring time, the more viscous the solution will be. When the stirring rod feels stringy when lifted, add it to the pump bucket for the best application effect.
2. When using a ground pump to transport concrete, the amount of water in the pump bucket should be appropriately increased. Before starting the pump, the horizontal pipe of the pump should be filled with water to ensure that every Some pipes can be wetted.
3. Before pumping, you must carefully check whether the pipe joints are tight to prevent leakage of liquid and slurry. Otherwise, the lubricant solution will leak from the joints and the lubrication will not be in place. , leading to pump clogging.
4. When pumping the first truck of concrete, pay close attention to whether the fluidity is appropriate to avoid excessive concrete slump and ensure that the first truck does not block the pump pipe.
Usage steps
1. First add normal temperature water to the hopper of the delivery pump and keep it The rotating shaft in the hopper rotates at a constant speed;
2. Pour the powdery lubricant into the hopper that rotates at a constant speed;
3. Stir slowly for about 5 minutes. The liquid in the hopper will be thick, uniform, colorless and transparent;
4. Moisten the tube Slowly pour the lubricating agent solution along the inner wall of the hopper of the conveying pump and then start the conveying pump until a small amount of lubricating agent sprays out;
5. As the lubricating agent flows in the pump Lubricating in the delivery pipe, the lubricating agent begins to spray out;
6. The pumping machine gradually reaches a constant state, and a large amount of lubricating agent is sprayed out;
7. The lubricant gradually disappears in the pipeline, and the concrete mixed with the pumping agent is sprayed out;
8. The pumped concrete is completely sprayed out, the lubricant is completed to lubricate the delivery pipe, and the concrete is pumped.
How to judge the quality of lubricant
Pump�Pipe moisturizing agents have been widely promoted and used due to their excellent chemical properties. Currently, there are a large number of pipe lubricating agents on the market, and the quality of the products is difficult to control. The specific judgment methods are:
1. Determination of the solubility of the lubricant. A good lubricant will turn into a viscous and transparent paste after being dissolved in water and stirred. A poor quality lubricant will mostly turn into a turbid state after being dissolved and white insoluble matter will appear at the bottom.
2. Determination of the solubility of lubricant. Usually, lubricants with stable ingredients and good quality can be completely dissolved at room temperature, while lubricants with poor quality may crystallize or harden when dissolved at room temperature. Failure to provide sufficient hot water under winter construction conditions will cause the solubility of the lubricating agent to decrease, affecting the lubricating effect and affecting pumping. </p
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