Measures of the Workability of Steel Fiber Reinforced Concrete and Their Precision

Abstract

Abstract Measurements of the workability of freshly mixed steel fiber reinforced concrete have been conducted using the traditional slump test, the British Standard V-B test and the test for time of flow through an inverted slump cone recently issued as ASTM Test Method for Time of Flow of Fiber Reinforced Concrete Through Inverted Slump Cone (C 995). Differences between the tests in terms of the extent to which they assess the stability, mobility, and compactability of fresh concrete are identified, and relationships between the results of each type of test are discussed in this context. The single-operator and between-operator precision of the results for each type of test are examined using four operators repeating each test three times on a total of 18 different mixtures with aggregate maximum size, fiber content, and fiber aspect ratio as the variables. Precision is analysed in terms of both standard deviation and coefficient of variation, and the dependence of each of these measures of precision on the magnitude of the mean is examined in terms of correlation coefficients. Using limits within which 90% of the 72 results for single-operator standard deviations fall, criteria suitable for precision statements are established for each of the three tests.