ACI SCC Testing flashcards
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- Slump flow test standard
- ASTM C1611; uses an inverted slump cone filled without rodding and measures the average of two perpendicular patty diameters as slump flow in inches or millimeters.
- Slump flow SF1 range
- ACI 237R classification: slump flow of 20 to 24 in (510 to 610 mm); represents lower flowability SCC suitable for less congested sections.
- Slump flow SF3 range
- ACI 237R classification: slump flow of 26 to 30 in (660 to 760 mm); highest flow class, used for heavily reinforced or difficult-to-access placements.
- T50 time
- Time in seconds for the slump flow patty to reach 20 in (500 mm) diameter; a shorter T50 indicates a higher flow rate and lower plastic viscosity.
- J-ring test standard
- ASTM C1621; a ring with 16 bars of 0.625 in (16 mm) diameter surrounds the slump cone to assess passing ability through reinforcing bars.
- J-ring blocking difference
- Difference between slump flow and J-ring flow diameters; a difference of about 1 in (25 mm) or less generally indicates acceptable passing ability.
- Visual stability index
- ASTM C1611 rating from 0 to 3 assigned to a slump flow patty; 0 is highly stable with no bleed and 3 shows severe segregation and mortar halo.
- Column segregation test
- ASTM C1610; a 26 in (660 mm) tall column stands 15 min, then three equal sections are washed over a No. 4 sieve to compare coarse aggregate masses.
- Segregation index formula
- (Maximum coarse aggregate mass minus minimum coarse aggregate mass) divided by the average mass of the three column sections; lower percentages indicate better stability.
- SCC vibration in field
- SCC should be placed continuously under its own weight; limited vibration only to release entrapped air, since over-vibration can cause segregation and instability.
- SCC sampling standard
- ASTM C172 governs sampling of fresh concrete; SCC samples must be representative and tested promptly because flow properties change with rest time.
- Mortar halo
- A ring of mortar and bleed water surrounding a slump flow patty; its presence signals instability and raises the visual stability index rating.
- Slump flow measurement
- Average of two perpendicular diameters of the patty measured after lifting the cone; reported in inches or millimeters and used to classify flowability.
- Passing ability definition
- Ability of SCC to flow through congested reinforcement without blocking or segregation; assessed by J-ring, L-box, and U-box tests.
- Filling ability definition
- Ability of SCC to flow and fill formwork under its own weight; assessed by slump flow, T50, and V-funnel tests.
- Segregation resistance definition
- Ability of SCC to remain homogeneous during transport and placement; assessed by column segregation, sieve segregation, and VSI.
- V-funnel test
- Fill a V-shaped funnel with about 5 L of concrete and time the outflow after opening the gate; typical SCC values are about 6 to 12 s.
- V-funnel time meaning
- Longer V-funnel times indicate higher plastic viscosity and lower flowability; shorter times indicate a more fluid, less viscous mixture.
- L-box test
- Concrete flows from a hopper through vertical bars into a horizontal channel; the blocking ratio H2/H1 is compared with a typical threshold of 0.8.
- L-box blocking ratio
- Ratio of concrete height at the far end (H2) to height at the gate end (H1); values of 0.8 or greater generally indicate acceptable passing ability.
- Orimet test
- Measures time for concrete to flow through an 80 mm (3.1 in) orifice at the base of a vertical pipe; a rapid indicator of flow rate and filling ability.
- U-box test
- A U-shaped box with vertical reinforcing bars; the height difference between the two sides after filling indicates filling and passing ability.
- Sieve segregation test
- Concrete placed on a No. 4 (4.75 mm) sieve drains for 2 min; the percentage of mortar passing the sieve indicates segregation resistance.
- No. 4 sieve size
- 4.75 mm (0.187 in) sieve opening; used in column segregation and sieve segregation tests to separate mortar from coarse aggregate.
- SCC specimen casting
- SCC test specimens are cast without mechanical consolidation, following ASTM C192 practice adapted for SCC, since the concrete self-consolidates under its own weight.
- Compressive strength standard
- ASTM C39 governs compressive strength testing of cylindrical concrete specimens; SCC typically shows high early strength and low permeability.
- Trial batch acceptance
- Compare slump flow, T50, J-ring, V-funnel, and segregation results against specified ranges; no single test fully characterizes SCC.
- Laboratory test temperature
- Fresh SCC tests are performed at a controlled ambient temperature, commonly 68 to 73 °F (20 to 23 °C), because flow and viscosity results are temperature sensitive.
- Inverted slump cone
- SCC slump flow uses the cone placed upside down (smaller opening up) and filled without rodding, unlike the conventional slump test.
- Plastic viscosity
- Resistance of SCC to flow; reflected by T50 and V-funnel times, with higher viscosity producing longer times and slower flow.
- J-ring flow measurement
- Average of two perpendicular diameters of the patty after concrete flows through the J-ring bars; compared with slump flow to assess blocking.
- SCC fresh test suite
- Combination of slump flow, T50, J-ring, V-funnel, and segregation tests; multiple tests together characterize filling ability, passing ability, and stability.