To provide a water-based resin composition for constructing a thick film, from which a thick film can be constructed on a treating surface of a concrete structure or the like, which can be dried within 12 hours after being applied, and whose applied coating film has excellent durability, for example, water resistance, acid resistance and alkali resistance; and to provide a surface treatment method using the same.

The water-based resin composition for constructing a thick film contains a water-based synthetic resin emulsion (A) and a glass filler (B), wherein a nonvolatile content is 65 to 80 mass%. The method for treating a treating surface includes applying the water-based resin composition for constructing a thick film to the treating surface and drying the resin composition to form a coating film having a film thickness of 0.1 to 2.0 mm. The method for treating a concrete structure surface includes applying the water-based resin composition for constructing a thick film to the concrete structure and drying the resin composition.