Self consolidating concrete

Several test procedures have been successfully employed to measure the plastic properties of Self-Consolidating Concrete. The slump flow test, using the traditional slump cone, is the most common field test and is in the process of being standardized by ASTM. The slump cone is completely filled without consolidation, the cone lifted, and the spread of the concrete measured. The spread can range from 18 to 32 inches (455 to 810 mm). The resistance to segregation is observed through a visual stability index (VSI). The VSI is established based on whether bleed water is observed at the leading edge of the spreading concrete, or if aggregates pile at the center. VSI values range from 0 for “highly stable” to 3 for unacceptable stability.

During the slump flow test, the viscosity of the SCC mixture can be estimated by measuring the time taken for the concrete to reach a spread diameter of 20 inches (500 mm) from the moment the slump cone is lifted up. This is called the T20 (T50) measurement and typically varies between 2 and 10 seconds for SCC. A higher T20 (T50) value indicates a more viscous mix which is more appropriate for concrete in applications with congested reinforcement or in deep sections. A lower T20 (T50) value may be appropriate for concrete that has to travel long horizontal distances without much obstruction.

A typical slump flow spread for Self-Consolidating Concrete (SCC) ranges from 18 to 32 inches (455 to 810 mm). Instead of measuring vertical drop like regular concrete, technicians measure the horizontal diameter of the spread using the Slump Flow Test (ASTM C 1611) . [1, 2, 3]

How It Is Measured

• Fill the Mold: Place a standard metal slump cone on a flat, non-absorbent base plate or Testing - Self board, often inverted. Fill it with fresh concrete in one single lift without rodding or tamping.

• Strike Off: Scrape the top flat so the concrete is level with the top of the cone.

• Lift the Cone: Pull the cone straight up smoothly and quickly.

• Measure Spread: Let the concrete flow out completely into a flat pancake shape. Measure the widest diameter of the spread, and measure a second perpendicular diameter to average them.

• Check Viscosity (T-50): Time how many seconds it takes for the spreading concrete to reach a 20-inch (500 mm) circle marked on the base plate (typically 2 to 10 seconds).

• Inspect Stability: Look for any separation of liquid or rocks at the edges to grade the mix stability. [1]

If you are working on a specific pour, would you like to know about passing ability tests like the J-Ring or how to check for segregation resistance?

AI responses may include mistakes.

[1] https://www.selfconsolidatingconcrete.org/testing.html

[2] https://concretecountertopinstitute.com/free-training/understanding-self-consolidating-concrete/

[3] https://www.youtube.com/watch?v=Gm9Adz5EPE4

[4] https://www.globalgilson.com/blog/self-consolidating-concrete

[5] https://www.hira.com.tr/En/Product/Slump-Flow-of-Self-Consolidating-Concrete

Distribution to Molds