Guide to Identification and Control of Visible Surface Effects of Consolidation on Formed Concrete Surfaces

Description

his guide is a reference source for specifiers, design engi-neers, architects, contractors, and other professionals who work with concrete surface finish of formed surfaces. The ability to identify or categorize negative surface effects is the first step in detecting the root cause of them. The goal of this guide is to differentiate between various negative surface effects to improve the concrete process and subse-quent concrete quality.

The cause of negative concrete surface effects is sometimes not correctly diagnosed. For example, air voids are usually attributed to lack of vibration in circumstances where the correct source of the imperfec-tion is ill-prepared formwork or improper selection of the form-release agent. With misdiagnosis, negative surface effects are likely to occur again because appropriate correc-tive actions have not been identified and taken.

This guide includes a summary of direct and indirect causes of negative surface effects in concrete surface finishes, along with photographs to illustrate them. The most serious effects resulting from ineffective consolidation procedures are also reviewed. They include honeycomb, cold joints, and exces-sive surface voids. A detailed description of these occur-rences and their causes are provided.

Of equal importance is the employment of properly trained and motivated supervi-sory and nonsupervisory construction personnel to achieve the intended concrete finishes and surface textures. Extreme negative surface effects do not always conform to the accept-able limits required by contract documents and might be considered defective work. Methods for minimizing surface effects are also discussed