Title: Concrete Aggregates Shape, Surface Texture, And Coatings
Author(s): Bryant Mather
Publication: Symposium Paper
Appears on pages(s): 57-78
A property of aggregate is "significant" from the viewpoint of this publication only if it has a significant effect on the behavior of portland-cement concrete in service. Similarly, a test of aggregate is "significant" only if it yields useful information about a significant property or group of properties. The behavior of concrete in service is determined by the interaction of certain of its properties and the significant characteristics of the exposure to which it is subjected. Variations in shape and surface texture of, or the presence of coatings on, aggregate particles may significantly affect properties of concrete that are important to its behavior in service. No ASTM methods exist by which quantitative determinations of particle shape, surface texture, or coatings can be made. Few satisfactory data are available concerning the relations between variation in these properties of aggregates and behavior of concrete. These properties have not been adequately defined, and adequate definition is necessary before satisfactory information can be obtained regarding the degree to which aggregates differ with respect to them. The nature and degree of differences among aggregates with respect to these properties must be satisfactorily determined before their effect on the behavior of concrete can be properly evaluated. The absence of satisfactory data is not due to failure of previous writers to suggest the probable significance of these properties. These properties are mentioned or discussed in the 1943 ASTM "Report on Significance of Tests of Concrete and Concrete Aggregates" in the papers by Gilkey , Hubbard , Kriege , and Lang ; and in the 1948 ASTM Symposium on Mineral Aggregates in the papers by Allen , Rhoades and Mielenz , Rockwood , Sweet , and Woolf . Reports of work done in Australia, Denmark, France, Germany, Great Britain, Japan, Sweden, Switzerland, and the United States are cited in the list of references at the end of this paper. Standardized test methods have been developed by Markwick [10,11] and Shergold [12,13] of the Road Research Laboratory in Great Britain; by Schiel [14-16], Walz , Schulz [18-20], Schulze , Pickel and Rothfuchs , Pickel , and the Forschungsgesellschaft fiir das Strassenwesen , in Germany; by von Matem  in Sweden; by Feret [26,27] in France; and by Goldbeck , Huang , and the Corps of Engineers [30-32] in the United States. The most careful studies of concepts and definitions of particle shape and surface texture have been made by sedimentary petrologists, notably Wentworth (33-35], Wadell [36-38], Zingg , Krumbein [40-42], Pettijohn , and Sneed and Folk . However, the relation of their work to aggregates for portland-cement concrete has received little attention, especially in the United States.