ACI 309.2R

Identification and Control of Visible Effects of Consolidation on Formed Concrete Surfaces

Year: 2005

Abstract: GENERAL
A formed concrete surface, uniformly smooth or deeply textured and essentially free of blemishes and color variation, is difficult to attain. Since repairs to a defective surface are costly and seldom fully satisfactory, the need for repairs should be minimized by establishing and maintaining the quality of the concrete operation and by adhering to acceptable consolidation procedures. Standards for surface finishes are beyond the scope of this report. Guidance for establishing appropriate standards is offered by the International Council for Building Research (CIB) (1975), which classifies formed surface finishes as follows:
• Special—High standards of appearance required (ACI 303R);
• Elaborate—Definite requirements for visual appearance;
• Ordinary—Appearance is of some importance; and
• Rough—No special requirements for finish.
Concrete construction procedures do not always provide the control necessary to consistently obtain blemish free concrete indicated by a special category.
To achieve any concrete finish, the designer and the contractor must use materials as well as design and construction practices that will keep surface effects within acceptable limits. There is a definite need for understanding the causes of unacceptable blemishes and effects encountered in concrete construction and a need for applying more effective measures to minimize or eliminate them. This report addresses those needs and its major emphasis is on consolidationrelated effects.
The most serious effects resulting from ineffective consolidation procedures are: honeycomb, subsidence cracks, cold joints, and excessive surface voids. A detailed description of the blemishes and their causes are provided in Table 1. Some imperfections may not conform to contract documents and may be considered as defective work.
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