Memorandum

The 1998 Standard Specifications have three concrete surface finishes. There will be only two concrete finishes in the new 2000 Standard Specifications as a result of the AGC/WSDOT Structures Team’s efforts and assistance from Alex Young.

Changing te specification involved numerous meetings over an eighteen month period to clarify what was acceptable and to negotiate procedures and wording. Here are a few issues:

• There was misinterpretation of the specification and lack of consistency on acceptable surface finished in the field.
• Class 1 concrete surface finish requires it to be sacked. If this surface was to receive pigmented sealer, it had to be sandblasted to provide an etch for the pigmented sealer to adhere. The sandblasting operation knocked off the mortar used in the sacking which created an unsightly surface.
• Fewer surface finish classes were desirable.
• Class 1 finish should be shown on the plans to eliminate misinterpretation in the field.

The attached sketch provides Notes to Designer and how to show Class 1 concrete surface finish limits in our plans.
Following is a brief summary of the changes:

• Concrete surface finish shall be determined at the preliminary plan stage with concurrence of the Bridge Architect.
• All concrete surfaces shall have a Class 2 finish unless designated as a Class 1 finish.
• Concrete surfaces receiving a pigmented sealer shall have a Class 2 finish.
• Class 1 concrete surfaces shall be designated on the contract plans. Class 2 finishes do not have to be identified in the plans.

See 6-02.3(14), A, B, and 6.02.3(25)H in the 2000 Standard Specification as they relate to concrete surface finishes.
The sketch will be shown in the next BDM update.

CCR/JVL

Attachments

cc:         J. A. Weigel, 47340

            Lewis, 47354

            F. Higgins, 47340