Solid waste recycling material pavement construction technology

The use of solid waste recycling materials to build roads does not require natural stones and sand, only coagulants and bulk solid wastes are used, which can well protect and improve the environment.

(1) Solid waste recycled pavement material, structure and performance

Smelting slag, gasification slag, slag, coal gangue, desulfurization gypsum, tailings slag, fly ash, red mud, domestic sludge, chemical sludge, phosphogypsum, construction waste, domestic waste incineration slag, weathered soil, alkali The mixture of industrial solid waste such as slag, construction waste, etc., cement and coagulant in proportion, has certain strength and durability, and its anti-freezing performance, water penetration resistance, sulfate corrosion resistance, and carbonization resistance. All are higher than the relevant performance requirements of concrete.

The solid waste recycled pavement material structure layer is divided into road surface layer, base layer and sub-base. When the structural layer is constructed in special climatic environments such as winter and rainy seasons, a special construction plan shall be formulated according to the actual situation of the project.

(2) Coagulant

It is an additive used to strengthen the chemical reaction and physical winding of solid waste recycled pavement materials, so that solid waste recycled pavement materials can form a stable complex structure and improve the water stability and strength of the surface layer of the structure.

(3) Factory mixing method

The construction method is to set up a mixing base in a centralized manner, and use special equipment to mix and prepare the recycled mixture.

(4) Composition and design steps of solid waste recycled pavement materials:

1. Determine the moisture content and specific gravity of raw materials and other indicators

2. The amount of coagulant should be selected according to 0.2%.

3. The heavy-duty compaction test method should be used to determine the optimum water content and maximum dry density of different cement contents, mixtures.

4. Calculate the dry density of the specimens with different cement content according to the specified degree of compaction.

5. Prepare solid waste recycled pavement material test pieces, the size of the test piece is Φ150mm╳150mm, and the number of test pieces is not less than 9.

6. The maintenance and compressive strength measurement of the specimen should refer to the relevant requirements of JTG E51 "Test Regulations for Inorganic Binder Stabilizing Materials of Highway Engineering".

7. According to the results of the 7d unconfined compressive strength test, the cement content and the coagulant content are selected, and the minimum cement content should not be less than 3%; the maximum dry density and the optimal moisture content are calculated by interpolation.

(5) Construction process and process requirements of solid waste recycled pavement materials

1. Mixing of solid waste recycled pavement materials

The production of solid waste recycled pavement materials adopts the intelligent patent mixer and supporting technology of Grace International Road.

The mixing shall be carried out according to the material specifications and proportions determined by the proportion design of solid waste recycled pavement materials.

The proportion of pellets in the raw materials is not less than 20%-30%, the size of the pellets is 5mm-8mm, and the base and low base layers can reduce the requirements.

The mixing plant shall provide the site with the product qualification certificate, the amount of cement, the amount of coagulant, the amount of solid waste admixture, the mixing ratio of the mixture, and the standard value of R7 strength.

2. Transportation of solid waste recycled pavement materials

A dump truck is used.

According to the size of the project and the length of the transportation distance, a sufficient number of transport vehicles are equipped. The compartment should be cleaned before loading, and there should be no sundries, and measures should be taken to prevent moisture loss after loading.

3. Paving of solid waste recycled pavement materials

(1) The stacking time of the mixture should not be too long, and it should not exceed 4 hours from the discharge of the mixer to the completion of paving and rolling. When the mixing plant is far away from the paving site, the amount of water used for mixing the mixture can be appropriately increased (generally controlled within 5%), and it should be covered during transportation to prevent water evaporation. The paver shall be paved in place as soon as possible according to the pre-set elevation and punctuation, and the corners that cannot be paved by the paver shall be paved in place manually at the same time and leveled to the specified elevation for paving.

(2) The compaction coefficient should be determined by test before construction. The compaction coefficient should be 1.10~1.33 (related to the material).

(3) The maximum compaction thickness of each layer of the mixture should not be greater than 200mm, and should not be less than 100mm.

(4) The mixture should not exceed 4h from stirring until the paving is completed. The amount of materials should be calculated according to the construction length of the shift.  

4. Rolling of solid waste recycled pavement materials

(1) When the compacted thickness of the road surface is 150mm-200mm, the large-scale retractable paver is used for paving, and the 22-26-ton rubber tire road roller and the 6--8-ton double steel wheel are used for rolling and forming.

(2) When the compacted thickness of the road surface is 100mm-150mm, the large-scale retractable paver should be used for paving, and the 22-ton rubber wheel roller and the 3-6-ton double steel wheel should be used for rolling and forming.

(3) Roll forming at one time within the specified time.

(4) During the rolling process, the surface of the mixture should always be kept moist. The straight section of the road surface is rolled from the shoulders on both sides to the center of the road; the flat curve section is rolled from the inner shoulder to the outer shoulder. When rolling, the rear wheel should overlap 1/2 of the wheel width and must exceed the seam between the two sections. When the rear wheel compacts the full width of the road, it is one pass, and the rolling is carried out until the required compactness. The two sides of the road should be pressed twice more. destroy. Small-scale road rollers should be used for the corners that cannot be rolled by the road roller, and the workers should roll them in place, generally 2 to 3 times more than the road surface, until they are compacted and reach the specified elevation. After compaction, the surface should be flat without wheel traces or bulges, and the cross section should be correct, and the road arch should meet the requirements.

(5) When the compaction thickness of the paved roadbed exceeds 20 cm, it shall be paved in layers of 20 cm per layer, and the minimum compaction thickness of each layer shall be 10 cm. When the paving layer is more than one layer, first lay one layer, if the next layer is laid on the same day, it needs to be completed within 6 hours, otherwise the next layer needs to be laid after 2 days.

5. Stubble connection and maintenance of the base of the mixture

After the pavement is compacted and formed, cover it with plastic film for 2-7 days. When the temperature is above 30°C, cut the construction joint after one day. When the temperature is lower than 30°C, cut the construction joint after 2-3 days. In order to ensure the quality, construction is not allowed below 0°C. The pavement construction joints are set at 3 times the road width, and the joint width is 10-15mm. When the strength reaches about 10Mpa, use a slitter to cut the construction seam. When the front and rear construction joints are connected, the hardened road surface should be cut neatly with a cutting machine, and the hardened road surface should not be damaged during subsequent construction and rolling. The side slopes on both sides of the road shall be compacted in place simultaneously with the road surface by manual manual small drum rollers, and the construction shall be in place according to the elevation and size required by the drawings, and the roadbed slopes shall be reasonably connected. It can be put into use after 3-7 days of road maintenance.