In the process of asphalt pavement repair, the core function of spraying emulsified asphalt is to enhance interfacial adhesion, seal voids, and provide waterproofing and seepage prevention. It also improves the integrity and durability of the repair layer and the original pavement. Specifically, its functions can be divided into the following:

Adhesive Layer Function: Strengthening interlayer bonding: After demulsification, the asphalt particles in the emulsified asphalt form a continuous asphalt film, tightly bonding the new asphalt mixture to the old asphalt layer and base course of the original pavement. This prevents the “two-layer” phenomenon and prevents the repair layer from shifting or detaching under vehicle loads.
Waterproofing and Seepage Prevention: Protecting the pavement structure: The sprayed emulsified asphalt fills the gaps between the original pavement and the repair layer, forming a waterproof barrier that prevents rainwater and snowmelt from seeping into the pavement structure. Moisture infiltration is a major cause of base course softening, subgrade settlement, and pavement cracking. The waterproofing effect of emulsified asphalt effectively extends the overall service life of the pavement.
Waterproofing and Seepage Prevention: The sprayed emulsified asphalt fills the gaps between the original pavement and the repair layer, forming a waterproof barrier that prevents rainwater and snowmelt from penetrating the pavement structure. Pre-coating and maintenance enhance asphalt mixture performance. During repair work, if the original pavement base or old material surface is dry and loose, spraying emulsified asphalt can pre-coat the aggregate particles, reducing aggregate segregation during new mixture paving. It also provides temporary curing, preventing shrinkage cracks in the base layer due to rapid water loss.
Adjusting interface properties adapts to construction conditions. Emulsified asphalt is a water-based material, requiring no heating (or low-temperature heating) during construction. It can be sprayed at room temperature, with lower requirements for the environment and construction equipment. Especially in low-temperature and humid environments, the demulsification and curing of emulsified asphalt adapts better to construction conditions, offering greater flexibility compared to hot asphalt.
In short, emulsified asphalt plays a dual role in asphalt pavement repair as a “binder + waterproofing agent,” a crucial step in ensuring repair quality and extending pavement service life.