How do we distinguish the quality of concrete mixing station？The quality of cement is directly related to the quality and durability of the building, and is also the key link in the quality control of the mixing station!However, the current order of the cement industry is not good: unqualified clinker in cement clinker is widespread, the content is far below the standard value is normal, small cement can not be called cement, can only be called powder。Cement supervision is seriously missing!Testing strength, setting time and stability are far from enough。1、专业Batching machine图片Clinker: standard requirements, calcium silicate mineral is not less than 66%, calcium oxide and silicon oxide mass ratio is not less than 2。But are our cement factories often up to standard？Strength tests are usually performed only。2, cement clinker content: standard requirements, ordinary Portland cement clinker, gypsum content should be greater than or equal to 80%, less than 95%。But now, even if the large cement clinker content is generally only 65% to 70%, let alone the small cement plant near it in Beijing (in fact, can only be called the grinding station, do not know how to make a cement plant name), the general knowledge of small cement clinker is only about 50%。Small cement cannot be called cement。At best, it's a mixture!3.眉山专业Batching machineTest method: Cement supervision by Technical supervision Bureau，Random inspection once a year，Can't restrain the production of cement plant!The inspection items of the national inspection standards only have strength, setting time and stability，Some chemical indicators are far from adequate!These indicators are easily met with small cement!We should strictly test the clinker，Clinker content testing should be increased when accepting cement，Not only strength, setting time and stability should be tested，当然，Magnesium oxide, trisulfur oxide and other chemical indicators can not be less!

一.Selection of raw materials and their temperature control 1.Cement cement should give priority to Portland cement, ordinary Portland cement early strong cement, in order to improve the early strength of concrete, reduce the frequency of freezing damage。2.Sand and stone should be preferred to use inventory sand, because the relative water content of inventory sand is low, the production of frozen blocks is less, and the relative performance is stable;Such as the new sand in winter, the water content of the incoming sand should be strictly required (controlled below 4%) to reduce the freezing probability and the adjustment frequency of the mix ratio during production to ensure the quality of concrete。The relative moisture content of stones is low, the probability of producing frozen blocks is small, and it should be avoided by rain and snow。In order to ensure the normal use of aggregate, it is recommended to cover the sand and stone on the site with sand mesh or felt, so that it is protected from rain and snow, and can play a certain role in insulation。The accumulation height of yellow sand and gravel should be appropriately increased, and if the material is sufficient, 5-8m is appropriate to reduce the freezing layer and protect the internal temperature。3.Mixing water Mixing water is drinking water, winter construction should use hot water mixing, water temperature control at about 60 ° C, but not higher than 80 ° C。4.Antifreeze Antifreeze contains antifreeze components, antifreeze components can reduce the freezing point of water, so that concrete is still hydrating under negative temperature conditions。When testing and using admixtures, it is necessary to strictly control the properties of antifreeze and the amount of admixtures。5.Due to the different fineness of admixtures such as fly ash and mineral powder, the micro-aggregate effect occurs in concrete, which improves the compactness of concrete.专业Batching machineThat is, the strength, frost resistance and durability of concrete are improved, but fly ash and mineral powder can extend the hydration time of cement。Therefore, the amount of admixture should be appropriately reduced during construction in winter。二.In order to ensure the normal operation of the equipment and the normal production of concrete, the feeding port of the aggregate bin, the admixture tank and the mixer should be closed, and the hot spot (furnace and electric heating) should be set, and the electric heating should be added in the operation room when there is air conditioning。Conditions should be used boiler heating, heating pipe should be through the bone bin feeding port, admixture shed, pool, mixer shed and operation room, not only save time, labor, but also better ensure the concrete out of the machine temperature and performance。三.Concrete transport vehicles under the jurisdiction of the company's mixing transport vehicles, in the winter before construction outsourcing insulation, to the mixing truck insulation, to ensure that the temperature of the concrete during transport does not lose。After the mixer is loaded, it is strictly prohibited to add water to the car at will to prevent the quality of delivery from being affected by changes in the water-cement ratio of concrete during transportation。After the mixer shaper, the water in the tank should be cleaned in time to prevent ice from causing quality hazards。四.The control test personnel of the production process test the moisture content and temperature of the sand and stone every day, and the number of tests should be increased in rain and snow weather。Depending on the climatic conditions, the concrete only needs to be mixed with hot water, and the aggregate does not need to be heated。The quality inspection personnel should check the temperature of the mixing water before each opening, which should not be higher than 80 ° C to prevent the phenomenon of false coagulation in the concrete;It shall not be lower than 40 ° C to ensure that the temperature of concrete entering the mold shall not be lower than 5 ° C。Strictly control the amount of antifreeze, and extend the mixing time of concrete to ensure the uniformity of concrete。五.Quality control of concrete after application 1.Quality inspection personnel shall be arranged at the construction site, responsible for vehicle deployment and concrete quality control。Compress the unloading time of concrete as soon as possible to ensure the temperature of concrete entering the mold。2.Batching machine图片Before pouring concrete, the construction site quality inspector should check whether there are factors affecting the quality of concrete such as frozen blocks or snow on the surface of the formwork。3.After concrete pouring is completed, the construction unit should be notified in time to cover the concrete with plastic film and blanket and other thermal insulation maintenance work to ensure that the concrete is not damaged by freezing before the initial setting.The concrete shall not be watered and cured during winter construction, and the strength of the concrete shall reach 1.Before 2MPa, do not step on it, support the mold and load。4.After the concrete pouring is completed, the quality inspection personnel should remind the tank truck driver to clean the concrete mixing truck with water。5.After mold removal, the difference between the surface temperature of concrete and the ambient temperature is greater than 20℃, and the insulation covering maintenance measures should be taken。The quality of concrete not only needs the strict control of the mixing station, but also needs the support and close cooperation of the construction unit, and the above measures can ensure that high-quality concrete can be produced in winter。

Concrete mixing station is mainly composed of material storage system,Batching machine图片Material weighing system, material conveying system, mixing system, powder storage system, powder conveying system, powder metering system, water and admixture metering system and control system and other ancillary facilities。Mixing machine Mixing machine according to its mixing mode is divided into forced mixing and self-falling mixing。Forced mixer is the mainstream used in mixing stations at home and abroad.专业Batching machineIt can mix a variety of concrete such as fluid, semi-dry hard and dry hard。The self-falling mixing machine mainly mixes liquid concrete, which is rarely used in mixing stations。The forced mixer is divided into spindle planetary mixer, single horizontal shaft mixer and double horizontal shaft mixer according to the structural form。Among them, the double horizontal shaft forced mixer has good comprehensive performance。Weighing system Material weighing system is a key component that affects the quality of concrete and the cost of concrete production, which is mainly divided into three parts: aggregate weighing, powder weighing and liquid weighing。Under normal circumstances, the mixing station below 20 cubic meters per hour adopts the superposition weighing method, that is, the aggregate (sand, stone) is weighed with a scale, the cement and fly ash are weighed with a scale, the water and the liquid admixture are respectively weighed, and then the liquid admixture is put into the water weighing bucket before mixing。In the mixing station of more than 50 cubic meters per hour, the method of independent weighing of each material is used, and all weighing is controlled by electronic scales and computers。The weighing accuracy of aggregate is ±2%, the weighing accuracy of cement, powder, water and admixture is ±1%。

1, mixing system Mixing system by motor, reducer, a pair of open gear and chain drive, mixing device and mixing tank composition。The motor is mounted on the end face of the reducer, and drives the two horizontally configured mixing shafts to reverse equal speed rotation respectively through a pair of open gears and chain drives。The mixing shaft is supported in the groove mixing tank formed by welding steel plate。Each stirring shaft is equipped with six stirring blades, and the mixture in the stirring tank is driven by the stirring blades to make "mutual cutting and turning" operation and alternately move according to the spiral trajectory。The combination of horizontal eddy current and vertical reverse flow agitation makes the material get rapid and strong agitation。专业Batching machine图片Due to the small linear speed of the perimeter of the mixing blade, the energy consumption of the mixing concrete, the wear of the blade and the lining plate are much smaller than other mixers。The shape, quantity and arrangement of stirring blades are the main factors affecting the mixing quality and technical performance of the mixer。A special floating sealing device is provided for the connection of the mixing shaft and the two ends of the mixing tank。The sealing device is also equipped with a special oil feeder, the main mixing shaft rotates, and the oil feeder automatically supplies oil to each sealing part to ensure the lubrication of the mixing shaft shaft end seal and support。2. Feeding system Feeding system is composed of hoist, feeding rack, hopper, etc。When loading，Load the mixture to be stirred into the hopper，The starting winch motor drives the drum to rotate through the reducer，When the hoisting wire rope pulls the hopper up to a certain height along the loading rack track，A pair of rollers on the bottom of the hopper enter the feeder level fork，The door opens automatically，Feed the material into the mixing tank。3. The discharge device is equipped with a discharge door at two arcs on one side of the cylinder, which can be rotated around the horizontal axis to open and close the eyes through an electric push rod。The horizontal shafting at both ends is supported on a support seat fixed to the bottom of the mixing tank。The length of the discharge door is slightly shorter than that of the tank. When the discharge door is opened, most of the mix is discharged by its own weight, and the residual mix is forced out by the mixing blade, so that the discharge is clean and fast without segregation。The joints of the discharge door and the mixing tank are sealed with wear-resistant rubber strips, and the backing plate on the support seat can be adjusted to ensure the sealing after wear。4、 Batching machine图片Water supply system The water supply system is made of unipolar centrifugal pump and quantitative principle。Under the guise of adjusting the pointer on the water tank dial, different amounts of water can be supplied。The two spray pipes are located directly above the two mixing shafts。The inlet and outlet of the water tank is controlled by the joystick of the three-way valve。When the water tank is supplied, the three-way valve cuts off the water discharge pipe, and the water inlet pipe is closed when the water tank is discharged。5, rack The rack is composed of bottom frame, legs, railings, platform, ladder, etc。Except for the railing, the rest are connected by bolts to the rack, and the railing is inserted into the socket hole on the rack。6. Electrical system。