Difficult Concrete Mixtures

Long placement durations require special consideration for concrete mixtures. Extended slump retention, control of setting, pumpability, and finishability are all critical performance characteristics to monitor during trial batching.

SCC can be placed at faster placement rates, allowing contractors to speed up placements and reduce labor cost. Avoid problems with a thorough trial batching process that includes testing for segregation

Testing SCC involves some modified methods, such as the slump flow test (ASTM C 1611), shown in the progression of photos. Other SCC-specific tests include the column segregation test (ASTM C 1610), the J-ring test (ASTM C 1621), the segregation probe (ASTM C 1712), and specimen fabrication (ASTM C 1758).

Testing SCC involves some modified methods, such as the slump flow test (ASTM C 1611), shown in the progression of photos. Other SCC-specific tests include the column segregation test (ASTM C 1610), the J-ring test (ASTM C 1621), the segregation probe (ASTM C 1712), and specimen fabrication (ASTM C 1758).

Testing SCC involves some modified methods, such as the slump flow test (ASTM C 1611), shown in the progression of photos. Other SCC-specific tests include the column segregation test (ASTM C 1610), the J-ring test (ASTM C 1621), the segregation probe (ASTM C 1712), and specimen fabrication (ASTM C 1758).

The restrained ring shrinkage test (ASTM C 1581) determines the relative susceptibility to shrinkage cracking for comparison of concrete mixtures. High strength and high cementitious content mixtures are particularly prone to cracking and this test can be used in specifications to screen out crack prone concrete mixtures.

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