In the construction of expressway, high requirements are put forward for the granularity and gradation of concrete aggregate, especially for the needle-like content in basalt (diabase) gravel. In order to meet the requirements of particle size and gradation, particle shape, consistency of particle composition, cleanliness and 0.075 mm particle content, Shanghai Hengyuan has added a new type of sand making machine to the production line configuration to better meet the requirements of cement and asphalt for sand aggregate on expressway.
High-speed road aggregate production process:
The quarried stones are initially crushed by vibrating feeder to jaw crusher. The secondary crushing is completed by cone crushing. The material broken by cone is screened by vibrating screen. The material larger than 40 mm returns to cone crushing and re-crushes, forming a closed-circuit cycle. The material less than 40 mm enters the vertical impact crushing for shaping and crushing. The material which is broken by vertical impact is screened by finished product sieve, and the material which is larger than 20 mm is returned to the vertical impact breaking cycle, and the material which is less than 20 mm is transported to each finished product stack by belt conveyor.
Performance of sand aggregate production line:
Stone production line is highly automated; its production efficiency is high, operation cost is low, output is large, income is high; discharge size is adjustable, crushing rate is high, energy saving; finished stone particle size is uniform, grain shape is good, in line with the national high-speed material standards.
Standard for gravel aggregate for Expressway construction:
The quality of gravel aggregate used in expressway construction has higher standards, which puts forward higher requirements for crusher equipment. At present, there are many problems in the production of gravel in our country. For example, the crushed gravel particle size is generally coarse, the mixture segregation is serious; the needle flake content in the crushed stone exceeds the standard; the instability of the feeding material affects the gradation of the mixture, and so on, which have a great impact on the pavement construction and pavement quality. In order to ensure the quality of expressway, the relevant departments have strict standards for sand aggregate used in Expressway construction. Following is a brief introduction for the customers who are ready to engage in the supply of gravel aggregate for Expressway construction.
First, the shape of particles
Second, particle size and gradation
Third, consistency of particle composition
Fourth, keep the cleanliness of particles
Fifth, control the content of 0.075mm particles
After crushing by crusher, the stone should be cubic, the content of needle-like particles in coarse aggregate should not exceed 15%, and the ratio of minimum thickness to maximum length of needle-like particles system should be less than 1:3. The mechanical stability of angular particles is greater than that of circular particles.
Gradation is the most important characteristic of aggregate, which directly affects almost all the important characteristics of mixture, especially for asphalt concrete, high gradation accuracy can ensure that the Marshall stability and flow value of the concrete are in the optimal design conditions, otherwise it will reduce the service life of the pavement.
Ensuring the consistency of particle composition is very important to maintain the consistency of aggregate gradation composition and the consistency of each technical index. If the particle composition of the mixture changes greatly, it will obviously affect the quality and service life of the pavement.
The existence of harmful substances such as clay, grass and excessive dust formed by crushing operation on aggregate particles will cause the stripping and loosening of asphalt mixture, thus affecting the durability of asphalt pavement.
The content of 0.075mm particles in water-stabilized base mixtures should not exceed 5%-7%, so as to reduce the shrinkage of cement-stabilized aggregates and improve their scouring resistance. Coarse aggregate for asphalt pavement requires that the particle content of washing method is less than 0.075 mm and less than 1%, which is mainly to control the mud content which can dissolve in water.