01 Tack Coat Construction Regulations
After the base course of the asphalt mixture surface layer is completed, a tack coat should be sprayed immediately. It is essential to ensure that the tack coat completely penetrates the base course before proceeding with the surface layer paving. When selecting a tack coat, liquid asphalt or emulsified asphalt with excellent penetration should be preferred based on the base course type, and its specifications must conform to the requirements of Table 8.4.1.
The tack coat should ideally be sprayed immediately after the lime-stabilized or cement-stabilized base course has been compacted and is slightly dry but not yet hardened. Asphalt mixture should be paved and traffic closed within 1-2 days after spraying.

The selection and dosage of the tack coat are crucial steps in construction. The tack coat should be sprayed evenly. If any areas are missed, manual respraying is required. If excessive amounts are sprayed, stone chips or sand should be immediately spread to absorb the oil, and appropriate compaction should be carried out if necessary.
For tack coat construction equipment, asphalt distributors or manual asphalt distributors are recommended for spraying the tack coat. The nozzles of the spraying equipment must be compatible with the tack coat asphalt to ensure a mist-like spray, and the spray pipe height should be moderate so that the same location receives spray from 2-3 nozzles.
【Tack Coat Construction Steps】
During tack coat construction, ensuring the tack coat oil penetrates evenly into the base layer is crucial. To achieve this, construction should be carried out immediately after the base layer construction to ensure sufficient penetration of the tack coat oil.
【Tack Coat Oil Selection and Dosage】
When selecting the tack coat oil, liquid asphalt or emulsified asphalt with excellent penetration should be preferred based on the base layer type. The dosage and penetration depth of the tack coat oil should be determined through testing and must not exceed the specifications in Table 8.4.1.
【Construction Equipment and Curing】
The tack coat oil is preferably sprayed using an asphalt distributor. The curing time needs to be determined through testing based on the type of tack coat oil and climatic conditions. The asphalt mixture surface layer should be laid promptly after the diluent in the liquid asphalt has completely evaporated or the water in the emulsified asphalt has evaporated.
02. Regulations for Tack Coat Construction
【Applicable Situations and Tack Coat Selection】 When the interval between the upper and lower layers of a double- or multi-layer hot-mix asphalt pavement is long, and the existing pavement is contaminated, tack coat should be sprayed at the interface between these structures and the asphalt mixture layers, such as curbs and manholes. Fast-setting or medium-setting emulsified asphalt, modified emulsified asphalt, or fast-setting and medium-setting liquid petroleum asphalt are recommended for the tack coat. Specific specifications and dosages should be in accordance with Table 8.4.2. The base asphalt grade should be consistent with that of the main asphalt mixture.
【Tack Coat Dosage and Application Timing】 The type and dosage of tack coat should be determined through testing based on the type of the underlying layer. The requirements in Table 8.4.2 should be followed. If a thin layer of high-pore drainage pavement will be laid above the tack coat, the dosage is recommended to be increased to 0.6–1.0 L/m2. When asphalt layers are used simultaneously as a seal coat, modified asphalt or modified emulsified asphalt is recommended, with a dosage of no less than 1.0 L/m2. The optimal application time for the tack coat is on the same day the surface layer is laid.
【Joint Treatment】 At the joints between the pavement and curbs, manholes, etc., special adhesives such as PC-3 and PA-3 should be used for reinforcement. These adhesives effectively enhance the adhesion of the joints, ensuring the stability of the connection.
03 Seal Coating Construction Standards
【Seal Coating Materials and Construction Methods】 Modified asphalt or modified emulsified asphalt is recommended for the seal coat. The aggregate should be hard, wear-resistant, and clean, and the particle size distribution must meet the requirements. The mix proportions of the slurry seal mixture must be designed and tested to ensure compliance before use. The lower seal coat should be applied using a layer-by-layer method or a slurry seal method. The dosage of asphalt (or emulsified asphalt) and aggregate should be determined according to the mix design.
【Sealing Coat Construction Requirements and Inspection】 Ensuring the sealing coat is impermeable is a crucial requirement for construction. Sealing coat construction should ensure uniform application of the asphalt layer and aggregates, avoiding looseness, cracks, oil drips, bleeding, waviness, color difference, leakage, accumulation, and other contamination of other structures. Simultaneously, the quality and specifications of the aggregates must be tested, and the construction width should be randomly checked.
04 Impact of Climate Conditions on Construction and Inspection
【Construction Adjustments Under Adverse Weather Conditions】 When the temperature drops to 10℃ or below, or the wind force exceeds level 5, the application of the tack coat, primer coat, or sealing coat should be suspended. Furthermore, the quality inspection of the tack coat, primer coat, and sealing coat must strictly adhere to relevant standards and regulations.
【Material Quality Inspection Methods】 The asphalt used in the tack coat, primer coat, and sealing coat must conform to the relevant provisions of Section 8.1 of this specification in terms of type and grade. Simultaneously, the quality and specifications of the sealing coat aggregates must also meet the corresponding standards. Inspection methods include verifying the product's certificate of conformity, factory inspection report, and on-site re-inspection report.