The requirements of pumping concrete for its material and mixing ratio are different from ordinary concrete. Therefore, not any concrete mixture can be pumped. The so-called pumpability means that the concrete mixture should have the characteristics of smooth flow through the pipeline, low frictional resistance, no segregation, no clogging and good adhesion. When pumping with a stirring pump, the stirring pump must be used properly. The main parameter of the agitating tow pump is the pumping capacity. The pumping capacity is generally expressed by the maximum conveying capacity (displacement) and the maximum conveying pressure of concrete pumped per hour. The pumping capacity marked on the product nameplate of the stirring pump is based on specific conditions. Such as the quality of concrete, proportion, aggregate gradation, sand ratio, water-cement ratio, slump and stern tube layout during pumping operation.
So what are the requirements for the concrete raw materials for the mixing pump:
1.Cement
Cement is a hydraulic cementitious material. General cement includes portland cement, ordinary portland cement and slag portland cement, etc. They should meet GB175-99 and GB1344-99 standards.
2.Admixture
Fly ash is a common admixture for pumping concrete.
Adding finely ground fly ash to the pumped concrete can significantly improve the fluidity of the concrete mixture, reduce the shrinkage, and significantly improve the pumpability of the concrete. For large-volume concrete structures, adding a certain amount of fly ash can also reduce the hydration heat of cement, which is conducive to controlling the occurrence of temperature cracks.
3.Sand
River sand is commonly used in general engineering. The sand should meet the requirements of JGJ52-92 "Quality Standards and Inspection Methods for Sand for General Concrete". The thickness of the sand is divided by the coefficient mode. The medium sand for pumping concrete is generally used, and its modulus is (3.0-2.3).
4.Pebble
Stones are divided into igneous rocks, sedimentary rocks, and metamorphic rocks according to the geological genesis. Most of the igneous rocks are excellent stone materials. The stone used for pumping concrete should meet the "Quality Standard and Inspection Method for Crushed Stone or Pebble for General Concrete" JGJ53-92.
5.Additives
Materials that are mixed during or before mixing, and the amount of which is not more than 5% of the weight of the cement, and which can change the properties of the concrete as required, are called concrete admixtures. Commonly used are water reducer, gas supplement, coagulant, antifreeze and so on. The most commonly used is water reducing agent, and the quality of admixture should meet the "Quality Standard for Concrete Admixture" JBJ56-84.
The above is the requirement for the concrete raw material of the concrete pump, and we hope it will be helpful to everyone.
