1. Particle size. The crushed stone layer is from top to bottom, from small to large, and 90% of the broken surface is within the range of 30-60 degrees; Most of the broken particle size is within 15.2cm. The content of broken particle size greater than 20.5cm generally does not exceed 5%, and the particle size is concentrated in 2.5 ~ 15cm and greater than 75%; The dust content of the broken layer shall not be greater than 7%.
2. Grading. The gravel layer is within 0 ~ 10cm, and the gradation is controlled within the range of graded gravel (gravel); Within 0 ~ 15.2cm, the grading is close to the graded crushed (gravel) stone.
3. Modulus of resilience. The modulus (static) of crushed stone layer shall generally be greater than 500MPa, but should be less than 900MPa. The bearing plate method can be used to detect the modulus. The first test is conducted on the top surface of the old road base before crushing, and then the second test is conducted at the adjacent position (within 1m2 around the same measuring point) after crushing. The modulus value (static) of the crushed layer is calculated from the two calculation results, so as to reduce the calculation error caused by the thickness of the old cement concrete slab, Core drilling sampling can be carried out at the same time for thickness detection; For the modulus of crushed stone slab, the dynamic modulus can also be calculated through FWD test, and then the static modulus can be calculated according to the proportional relationship.
4. Spraying prime coat oil or emulsified asphalt (according to the engineering design requirements).
6、 Precautions for safe construction
1. Operate the equipment safely according to the operation manual and carry out maintenance and repair in time to ensure normal construction as planned;
2. When operating equipment construction, ensure that there are no idle personnel in the construction area;
3. When the equipment turns around and retreats, special staff shall direct the traffic;
4. Redundant construction materials and facilities, equipment and materials affecting safety shall not be placed in the working area;
5. During construction, ensure that other facilities, such as power supply facilities and drainage facilities, are not damaged;
6. Constructors must wear safety helmets, safety vests, etc. in the working area, and carry out construction education regularly;
7. The night parking of equipment shall not hinder the work of other construction units, and safety warning signs shall be placed around;
8. Actively cooperate with the work arrangement of the general contractor.