Analysis of Aggregate Distribution in Self-Consolidating Concrete

Concrete consists of several key ingredients: cement, water, and coarse and fine aggregate. Depending on the proportions of these ingredients, the strength and workability of a concrete mix can be affected adversely. Segregation is the separation of aggregate and cement paste, resulting in a lack of homogeneity. Self-consolidating concrete (SCC) does not require traditional consolidation; however, it can be affected by segregation. This project examines different SCC mixtures and establishes ranges of values for slump flow, T20 , Visual Stability Index (VSI), J-ring flow and J-ring flow spread that ensures proper aggregate distribution and therefore reduces the potential of segregation. With this data, the intent is to produce a method of analysis for determining the degree of segregation in SCC. Sixteen concrete wall sections were cast and core samples were taken from nine locations in the walls. Of the nine samples, two cores from each row were tested in compression and a third core was used for aggregation distribution analysis. These cores were cut lengthwise to enable a manual count of the limestone aggregate. Digital images of the cores were captured and processed by a program created in MATLAB. The program generated percentage values of amount of aggregate per core. The results from the program were compared with results from the manual count method and then with the fresh concrete properties to determine if certain properties are indicators of possible segregation