Standard Practice for Surface Cleaning Concrete for Coating – ASTM D4258
Significance and Use
Surface cleaning is used to prepare concrete surfaces for applying coatings intended for light-duty service.
Use of this practice alone is not intended where protective systems will be used for continuous or intermittent immersion, mechanical loading, or for protective systems needing optimum bond for satisfactory performance (see Practices D4259 and D4260).
Scope
This practice includes surface cleaning of concrete to remove grease, dirt, and loose material prior to the application of coatings. Procedures include broom cleaning, vacuum cleaning, air blast cleaning, water cleaning, detergent water cleaning, and steam cleaning.
This practice is not intended to alter the surface profile of the concrete but to clean the surface.
Standard Practice for Preparation of Concrete by Abrasion Prior to Coating Application – ASTM D4259
Significance and Use
This practice is used to prepare concrete for coatings where optimum bond is desired for service conditions such as continuous or intermittent immersion, temperature cycling, or mechanical loading.
Scope
This practice includes surface preparation of concrete to prepare the surface prior to the application of coatings.
This practice is intended to create a surface profile in concrete and to remove foreign materials and weak surface laitance.
Referenced Documents
ASTM Standards
D4260 Practice for Liquid and Gelled Acid Etching of Concrete
D4262 Test Method for pH of Chemically Cleaned or Etched Concrete Surfaces
D4263 Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method
D4285 Test Method for Indicating Oil or Water in Compressed Air
APA Architectural Precast Association
Architectural Precast Concrete Finishes Guide
https://www.archprecast.org/uploadedFiles/File/Color_and_Finish_Guide.pdf
Smooth Finish:
Smooth – As Cast:
Definition – Concrete is placed against hard, smooth form work to achieve a smooth “as cast” finish on the precast element.
Reasons for use
This method shows the natural beauty of concrete without trying to simulate any other building product.
A very clean definition of profile can be achieved with this surface.
If the surface is to be painted, this finish provides an excellent surface, while keeping cost. to a minimum.
Other Finishes:
Exposed Aggregate – Chemically Retarded and Sandblasted
Exposed Aggregate – Chemically Retarded and Waterwashed
Exposed Aggregate – Sandblasted
Smooth – Light Sandblast
Smooth – Acid Etch
Form Liners Finish
Tooled Finishes
Natural Stone Veneer Finish
Brick Face
Cast Stone – Dry Tamp Finish
PCI Precast/Prestressed Concrete Institute
Architectural Precast Concrete Guide Specification https://www.pci.org/GuideSpecifications
Finishes
Exposed panel faces shall be free of joint marks, grain, and other obvious defects. Corners, including false joints shall be uniform and straight. Finish exposed-face surfaces of architectural precast concrete units to match approved [design reference sample] and as follows:
Select type of finish from subparagraphs below if needed. See PCI MNL 117 for more information on finishes.
As-Cast Surface Finish
Textured-Surface Finish
Bushhammer Finish
Exposed Aggregate Finish
Abrasive-Blast Finish
Acid-Etched Finish
Honed Finish
Polished Finish
Sand-Embedment Finish
Thin Brick Facings
Stone Veneer Facings
Structural Precast Concrete Guide Specification
Finishes
Commercial (Structural) Finishes:
Commercial Grade
Standard Grade
Grade B Finish
Grade A Finish
Specify Grade A Finish where surface will be painted (especially with a textured or “sand” paint); however, some surface blemishes will be visible. If a surface with fewer imperfections than allowed for “Grade A” is needed, specify the requirements as a “special finish.” Specify a sample panel for a Grade A Finish. Requirements for Grade A Finish are not applicable to extruded products using zero-slump concrete in their process.
Screed or Float Finish – unformed surfaces
Smooth Steel-Trowel Finish – unformed surfaces
Apply roughened surface finish in accordance with ACI 318 (ACI 318M) to precast concrete members that will receive concrete topping after installation.