As the aggregate of dry mix mortar, dry sand is generally not used directly. It can be directly used as ordinary mortar under the condition that raw sand classification is relatively reasonable. However, most raw sand classification cannot achieve reasonable gradation.The so-called classification is to fill the gap which is exist in coarse sand, and fill the fine sand gap with finer sand. In theory, the more detailed the grading of sand, the more dense and stronger the mortar will be. Using cement to fill the gap can achieve the purpose of both meeting the mortar strength and less cement consumption, so as to save the raw material cost of mortar. The classification system should be designed according to the characteristics of raw sand, mortar varieties and other factors. Classification screen, linear screen, circular vibrating screen, etc., can be selected for the grading screen. At the same time, the screening machine should have online screen cleaning function.The grading system shall set online sampling device after the grading screen to monitor the graded sand. If the lower sand contains the upper sand, the screen may have been damaged or the seal may have failed.The sampling port shall also be blocked to prevent parts of the grading system from falling off and entering the sand storage bin.The grading system shall also be equipped with dust removal device. The dust collected by the dust removal device shall be disposed according to the requirements of the preparation. 
The raw materials of dry mix mortar generally need to be stored in different storage bins. The most commonly used ones are sand bin, powder bin, additive bin and finished product bin.All silos require a material level control system. The material level can be high or low or continuous.According to the different nature of materials and the size of the bin, a flow aid device is set.Dry sand has good fluidity, generally can not set up the aid device;Pneumatic flow aid device is often used in powder bin.The additive silo is usually small in size and small in storage.The bin shall be provided with a vent and a dust collecting device.According to the nature of stored materials, a dust collecting device can be used for sand bin and finished product bin, and powder bin and additive bin should be set independently.The finished product silo is used to store the finished product of dry mix mortar. When the finished product enters the silo, the height of the finished product is relatively high. The finished product mortar presents a showering state in the falling process.The specifications of the powder bin should not only meet the production needs but also meet the requirements of the bulk carrier. The storage capacity of the storage bin should be larger than the quantity of one tank per transport truck, which can save the transportation cost of the powder.