The properties of the two materials are basically the same. Both have asphalt components and have air bonding effects. The editor of the asphalt mixing plant will share with you;
Cold primer was the earliest to be diluted and applied with diesel and asphalt to play a bonding role. Emulsified asphalt is a modified alternative product with better quality and high bonding strength. It can be used as a substitute, but the quality is not as good as the latter. From the perspective of engineering cost analysis, the former is cheaper.

Emulsified asphalt is a road asphalt that is usually used at high temperatures. After mechanical stirring and chemical stabilization (emulsification), it is diffused into water and liquefied into a road construction material with very low viscosity and good fluidity at room temperature. It can be used at room temperature and can be used with cold and wet stones. When the emulsified asphalt breaks and solidifies-it is reduced to a continuous asphalt and the water is completely removed, the final strength of the road material can be formed. In many road construction applications, emulsified asphalt provides a safer, energy-saving and environmentally friendly system than hot asphalt because this process avoids high-temperature operation, heating and harmful emissions.
Emulsified asphalt is mainly used for road upgrading and maintenance, such as stone chip seal, and there are many unique applications that cannot be replaced by other asphalt materials, such as cold mix and slurry seal. Emulsified asphalt can also be used in new road construction, such as tack coat oil, penetration coat oil, etc.
Cold primer is the product of diluting asphalt with diluents (gasoline, diesel, kerosene, benzene, etc.). It is mostly used as the base layer of waterproofing projects at room temperature, so it is called cold primer.
Cold primer has low viscosity and good fluidity. When applied to base surfaces such as concrete, mortar or wood, it can quickly penetrate into the pores of the base layer, and after the solvent evaporates, it will firmly bond with the base surface. The coating film formed by cold primer is relatively thin, and it is generally not used as a waterproof material alone, but only as a supporting material for some waterproof materials. During construction, a layer of cold primer is first applied on the base layer, and then asphalt waterproof coating or tarpaulin is applied. Cold primer can close the capillary pores of the base layer, and use the base layer to form waterproof ability; it makes the surface of the base layer hydrophobic, creating favorable conditions for bonding similar waterproof materials. I hope the content shared by the editor of the asphalt mixing station can help you!