2 Properties OF Fresh Concrete Elasticity and Strength Of ConcreteThe elastic properties of materials are a measure of their resistance to deformation under an applied load (but the elastic strain is recovered when the load is removed).Strength usually refers to the maximum stress that a given kind of sample can carry.Understanding these properties and how they are measured is essential for anyone wishing to use materials
3 Main Prop. OF Fresh Concrete ConsistencySlump TestFlow TestPenetration TestWorkabilityCompacting Factor TestVeBe Time TestSegregation---BleedingBleeding Water Test
5 Concrete ConsistencyConsistency or fluidity of concrete is an important component of workability and refers in a way to the wetness of the concrete.However, it must not be assumed that the wetter the mix the more workable it is. If a mix is too wet, segregation may occur with resulting honeycomb, excessive bleeding, and sand streaking on the formed surfaces
6 Concrete ConsistencyOn the other hand, if a mix is too dry it may be difficult to place and compact, and segregation may occur because of lack of cohesiveness and plasticity of the paste.
7 3 Ways to determine Consistency of Fresh Concrete Consistency TestsSlump TestBall penetration testFlow Test
8 Slump Test Definition Principle A slump test is a method used to determine the consistency of concrete. The consistency, or stiffness, indicates how much water has been used in the mix. The stiffness of the concrete mix should be matched to the requirements for the finished product qualitySlump is a measurement of concrete’s workability, or fluidity.It’s an indirect measurement of concrete consistency or stiffness.PrincipleThe slump test result is a measure of the behavior of a compacted inverted cone of concrete under the action of gravity. It measures the consistency or the wetness of concrete.
9 Slump TestApparatusSlump cone : frustum of a cone, 300 mm (12 in) of height. The base is 200 mm (8in) in diameter and it has a smaller opening at the top of 100 mmScale for measurement,Tamping rod(steel) 15mm diameter, 60cm length.
10 Slump TestProcedureThe base is placed on a smooth surface and the container is filled with concrete in three layers, whose workability is to be tested .Each layer is tamped 25 times with a standard 16 mm (5/8 in) diameter steel rod, rounded at the end.When the mold is completely filled with concrete, the top surface is struck off (leveled with mold top opening) by means of screening and rolling motion of the temping rod.The mold must be firmly held against its base during the entire operation so that it could not move due to the pouring of concrete and this can be done by means of handles or foot – rests brazed to the mold.
11 Slump TestProcedureImmediately after filling is completed and the concrete is leveled, the cone is slowly and carefully lifted vertically, an unsupported concrete will now slump.The decrease in the height of the center of the slumped concrete is called slump.The slump is measured by placing the cone just besides the slump concrete and the temping rod is placed over the cone so that it should also come over the area of slumped concrete.The decrease in height of concrete to that of mould is noted with scale. (usually measured to the nearest 5 mm (1/4 in).
12 Slump Test Precautions In order to reduce the influence on slump of the variation in the surface friction, the inside of the mold and its base should be moistened at the beginning of every test, and prior to lifting of the mold the area immediately around the base of the cone should be cleaned from concrete which may have dropped accidentally.
13 Slump Test Types Of Slump The slumped concrete takes various shapes, and according to the profile of slumped concrete, the slump is termed as;Collapse SlumpShear SlumpTrue Slump
14 Slump Test Types Of Slump Collapse Slump In a collapse slump the concrete collapses completely.A collapse slump will generally mean that the mix is too wet or that it is a high workability mix, for which slump test is not appropriate.Shear SlumpIn a shear slump the top portion of the concrete shears off and slips sideways. ORIf one-half of the cone slides down an inclined plane, the slump is said to be a shear slump.If a shear or collapse slump is achieved, a fresh sample should be taken and the test is repeated.If the shear slump persists, as may the case with harsh mixes, this is an indication of lack of cohesion of the mix.
15 Slump Test Types Of Slump True Slump In a true slump the concrete simply subsides, keeping more or less to shapeThis is the only slump which is used in various tests.Mixes of stiff consistence have a Zero slump, so that in the rather dry range no variation can be detected between mixes of different workability.However , in a lean mix with a tendency to harshness, a true slump can easily change to the shear slump type or even to collapse, and widely different values of slump can be obtained in different samples from the same mix; thus, the slump test is unreliable for lean mixes.
16 Slump TestUsesThe slump test is used to ensure uniformity for different batches of similar concrete under field conditions and to ascertain the effects of plasticizers on their introduction.This test is very useful on site as a check on the day-to-day or hour- to-hour variation in the materials being fed into the mixer. An increase in slump may mean, for instance, that the moisture content of aggregate has unexpectedly increases.Other cause would be a change in the grading of the aggregate, such as a deficiency of sand.Too high or too low a slump gives immediate warning and enables the mixer operator to remedy the situation.This application of slump test as well as its simplicity, is responsible for its widespread use.
17 Use for which concrete is suitable Slump TestDegree ofworkabilitySlump (mm)CompactingFactorUse for which concrete is suitableVery low0 - 250.78Very dry mixes; used in road making. Roads vibrated by power operated machinesLow0.85Low workability mixes; used for foundations with light reinforcement. Roads vibrated by hand operated MachinesMedium0.92Medium workability mixes; manually compacted flat slabs using crushed aggregates. Normal reinforced concrete manually compacted and heavily reinforced sections with vibrationsHigh0.95High workability concrete; for sections with congested reinforcement. Not normally suitable for vibration>Table : Workability, Slump and Compacting Factor of concrete with 19 or 38 mm (3/4 or 11/2 in) maximum size of aggregate.
18 Slump Test Consistency Dry Stiff Plastic Wet Sloppy Slump (mm) 0 - 20 ConsistencyDryStiffPlasticWetSloppy>Table : Relation between Consistency and Slump values
20 Flow TestDefinitionThe flow table test or flow test is a method to determine the consistence of fresh concrete.Application When fresh concrete is delivered to a site by a truck mixer it is sometimes necessary to check its consistence before pouring it into formwork.If the consistence is not correct, the concrete will not have the desired qualities once it has set, particularly the desired strength. If the concrete is too pasty, it may result in cavities within the concrete which leads to corrosion of the rebar, eventually leading to the formation of cracks (as the rebar expands as it corrodes) which will accelerate the whole process, rather like insufficient concrete cover. Cavities will also lower the stress the concrete is able to support.
21 Flow Test Equipment Flow table with a grip and a hinge, 70 cm x 70 cm. Abrams cone, open at the top and at the bottom - 30 cm high, 17 cm top diameter, 25 cm base diameterWater bucket and broom for wetting the flow table.Tamping rod, 60 cm heightScale for measurement
22 Flow Test Conducting The flow table is wetted. The cone is placed on the flow table and filled with fresh concrete in two layers, each layer 25 times tamp with tamping rod.The cone is lifted, allowing the concrete to flow.The flow table is then lifted up several centimeters and then dropped, causing the concrete flow a little bit further.After this the diameter of the concrete is measured in a 6 different direction and take the average.
27 Ball Penetration Test (Kelly Ball) DefinitionAnother method used in the field and laboratory to measure the consistency of concrete is the ball penetration test (ASTM C360) which is also known as the Kelly ball test*.ProcedureIt is performed by measuring the penetration, in inches, of a 6-in. diameter steel cylinder with a hemi spherically shaped bottom , weighing 30 lbs.
28 Ball Penetration Test (Kelly Ball) AdvantagesOne of the advantages of the ball penetration test can be performed on the concrete in a hopper, buggy, wheelbarrow, or other suitable container.Another advantage of this method is its simplicity and the rapidity with which the consistency of the concrete can be determined.It is also not dependent on a procedure of filling and rodding a container like the slump test.
30 Concrete Workability Definition The property of fresh concrete which is indicated by the amount of useful internal work required to fully compact the concrete without bleeding or segregation in the finished product.Workability is one of the physical parameters of concrete which affects the strength and durability as well as the cost of labor and appearance of the finished productConcrete is said to be workable when it is easily placed and compacted homogeneously i.e without bleeding or Segregation. Unworkable concrete needs more work or effort to be compacted in place, also honeycombs &/or pockets may also be visible in finished concrete.
31 Concrete Workability Factors affecting workability Water content in the concrete mixAmount of cement & its PropertiesAggregate Grading (Size Distribution)Nature of Aggregate Particles (Shape, Surface Texture, Porosity etc.)Temperature of the concrete mixHumidity of the environmentMode of compactionMethod of placement of concreteMethod of transmission of concrete
32 Concrete Workability How To improve the workability of concrete increase water/cement ratioincrease size of aggregateuse well-rounded and smooth aggregate instead of irregular shapeincrease the mixing timeincrease the mixing temperatureuse non-porous and saturated aggregatewith addition of air-entraining mixturesAn on site simple test for determining workability is the SLUMP TEST.
33 Compacting Factor Test IntroductionProcedureApparatus
34 Compacting Factor Test IntroductionThese tests were developed in the UK by Glanville ( 1947 ) and it is measure the degree of compaction For the standard amount of work and thus offer a direct and reasonably reliable assessment of the workability Of concrete . the test require measurement of the weight of the partially and fully compacted concrete and the ratio the partially compacted weight to the fully compacted weight, which is always less than one, is known as compacted factor .For the normal range of concrete the compacting factor lies between
35 Compacting Factor Test ApparatusTrowelsHand Scoop (15.2 cm long)Rod of steel or other suitable material(1.6 cm diameter, 61 cm long roundedat one end ).Balance.
36 Compacting Factor Test ProcedureEnsure the apparatus and associated equipment are clean before test and free from hardened concrete and superfluous water .Weigh the bottom cylinder to nearest 10gm , put it back on the stand and cover it up with a pair of floats .Gently fill the upper hopper with the sampled concrete to the level of the rim with use of a scoop .Immediately open the trap door of the upper hopper and allow the sampled concrete to fall into the middle hopper .Remove the floats on top of the bottom cylinder and open the trap door of the middle hopper allowing the sampled concrete to fall into the bottom cylinder .Remove the surplus concrete above the top of the bottom cylinder by holding a float in each hand and move towards each other to cut off the concrete across the top of cylinder
37 Compacting Factor Test Wipe clean the outside of cylinder of concrete and weigh to nearest 10gm .Subtract the weight of empty cylinder from the weight of cylinder plus concrete to obtain the weight of partially compacted concrete .Remove the concrete from the cylinder and refill with sampled concrete in layers .Compact each layer thoroughly with the standard Compacting Bar to achieve full compaction .Float off the surplus concrete to top of cylinder and wipe it clean .Weigh the cylinder to nearest 10gm and subtract the weight of empty cylinder from the weight of cylinder plus concrete to obtain the weight of fully compacted concrete .
41 VeBe Time Test Definition Apparatus It is based on measuring the time (Called VEBE time) needed to transfer the shape of a concrete mix from a frustum cone to a cylinder (these shapes are standardized by the apparatus of this test), by vibrating and compacting the mix. The more VEBE time needed the less workable the mix is. This method is very useful for stiff mixes.ApparatusCylindrical container with diameter = 240 mm, and height = 200 mmMold: the same mold used in the slump test.Disc : A transparent horizontal disc attached to a rod which slides verticallyVibrating Table : 380*260 mm, supported by four rubber shock absorbersTamping RodStop watch
42 VeBe Time Test Procedure Slump test as described earlier is performed, placing the slump cone inside the sheet metal cylindrical pot of the consist meter.The glass disc attached to the swivel arm is turn and place on the top of the concrete in the pot.The electrical vibrator is then switched on and simultaneously a stop watch started.The vibration is continued till such time as the conical shape of the concrete disappears and the concrete assume a cylindrical shape.This can be judge by observing the glass disc from the top disappearance of transparency.Immediately when the concrete fully assume a cylindrical shape, the stop watch is switched off.
43 VeBe Time TestThe time required for the shape of concrete to change from slump cone shape to cylindrical shape in second is known as Vibe Degree.This method is very suitable for very dry concrete whose slump value cannot be measure by slump test, but the vibration is too vigorous for concrete with slump greater than about 50m. The test fails if VeBe Time is less than 5 seconds .. And the test must be created when no collapse or shears slump in concrete
45 Concrete Segregation Definition WEAKER, LESS DURABLE, Segregation is when the coarse and fine aggregate, and cement paste, become separated. Segregation may happen when the concrete is mixed, transported, placed or compactedSegregation makes the concreteWEAKER,LESS DURABLE,and will leave A POOR SURFACE FINISH ^_*
46 Concrete Segregation Basic types of segregation Coarse segregation : Occurs when gradation is shifted to include too much coarse aggregate and not enough fine aggregate. Coarse segregation is characterized by low asphalt content, low density, high air voids, rough surface texture, and accelerated rutting and fatigue failure (Williams et. al., 1996b). Typically, coarse segregation is considered the most prevalent and damaging type of segregation; thus segregation research has typically focused on coarse segregation. The term “segregation” by itself is usually taken to mean “coarse segregation.”Fine segregation : Occurs when gradation is shifted to include too much fine aggregate and not enough course aggregate. High asphalt content, low density, smooth surface texture, accelerated rutting, and better fatigue performance characterize fine segregation (Williams, Duncan and White, 1996).
47 Concrete Segregation To Avoid Segregation Check the concrete is not 'too wet' or 'too dry'.Make sure the concrete is properly mixed. It is important that the concrete is mixed at the correct speed in a transit mixer for at least two minutes immediately prior to discharge.The concrete should be placed as soon as possible.When transporting the mix, load carefully.Always pour new concrete into the face of concrete already in place.When compacting with a poker vibrator be sure to use it carefully
48 Concrete Segregation To Avoid Segregation If placing concrete straight from a truck, pour vertically and never let the concrete fall more than one-and-a-half meters.
51 Concrete Bleeding Introduction This refers to the appearance of water along with cement particles on the surface of the freshly laid concrete. This happens when there is excessive quantity of water in the mix or due to excessive compaction. Bleeding causes the formation of pores and renders the concrete weak. Bleeding can be avoided by suitably controlling the quantity of water in the concrete and using finer grading of aggregates.A thorough knowledge of why concrete bleeds and how mix proportions affect it, is required to preventing the harmful effects of bleeding. Adoption of right finishing methods also helps to ensure that the bleeding problems won't ruin a slab surface.
52 Concrete Bleeding Bleeding Process Almost all freshly placed concrete bleeds. As aggregate and cement particles settle, they force excess mixing water upward. The process continues until settlement stops, either because of solids bridging or because the concrete has set.The total amount of bleeding or settlement depends on mix properties, primarily water content and amount of fines (cement, fly ash, fine sand). Increasing water content increases bleeding, and increasing the amount of fines reduces bleeding. Amount of bleeding is also proportional to the depth of concrete placed. More bleed water rises in deep sections than in thin ones.Bleeding usually occurs gradually by uniform seepage over the whole surface, but sometimes vertical channels form. Water flows fast enough in these channels to carry fine particles of cement and sand, leaving "wormholes" in the interior or sand streaks at the form face. Channels are more likely to form when concrete bleeds excessively.Channels that reach the surface are open paths for deicing solutions to penetrate the concrete. This leads to freezing and thawing damage and rebar corrosion.
53 Concrete Bleeding Effects Of Excessive bleeding in Deep Section Sometimes bleedwater can't entirely evaporate because it has been trapped near the top surface by setting. This raises the water-cement ratio, increases permeability, and lowers strength. Excessive bleeding also causes some other problems in deep sections: heavy laitance accumulation at horizontal construction joints; bond loss at aggregate and rebar surfaces; and unsightly sand streaks.Bleeding Problems in FlatworkNever float or trowel concrete while there's bleedwater on the surface. That's the cardinal rule of finishing. Finishing before bleedwater has evaporated can cause dusting, craze cracking, scaling, and low wear resistance. Working bleed-water into the surface also increases permeability.
54 Concrete Bleeding How to control bleeding Excessive bleeding can be avoided. Don't add too much water to the concrete. Most of the water added to make placing easier bleeds out of the concrete. Any time saved during placement will be lost while waiting for the bleedwater to evaporate. Place concrete at the lowest possible slump. If you need a higher slump to speed placement, consider using a super plasticizer. Add additional concrete fines to reduce bleeding. The fines may come from a number of sources:Use a more finely ground cement. Concretes made with high early strength (Type III) cement bleed less because the cement is ground finer than normal (Type I) cement.Use more cement. At the same water content, rich mixes bleed less than lean mixes.Use fly ash or other pozzolans in the concrete.If concrete sands don't have much material passing the No. 50 and 100 sieves, blend in a fine blow sand at the batch plant.For air- entrained concrete, use the maximum allowable amount of entrained air. Consider using an air- entraining agent whenever excessive bleeding is a problem. Entrained air bubbles act as additional fines. Air entrainment also lowers the amount of water needed to reach a desired slump.
55 6 Tests to determine SCC Properties (Self Consolidating Concrete) SCC TestsSlump Flow TestJ-Ring TestL-Box TestV-Funnel TestOrimet TestPenetration test
57 Slump Flow Test Definition Apparatus The slump flow test aims at investigating the filling ability of SCC. It measures two parameters: flow spread and flow time T50 (optional). The former indicates the free, unrestricted deformability and the latter indicates the rate of deformation within a defined flow distance.ApparatusBase plate of size at least 900 × 900 mmAbrams cone with the internal upper/lower diameter equal to 100/200 mm and the height of 300 mmWeight ring (>9 kg) for keeping Abrams cone in place during sample fillingStopwatchRuler (graduated in mm)Bucket with a capacity of larger than 6 litersMoist sponge or towel for wetting the inner surface of the cone
58 Slump Flow Test Procedure Place the cleaned base plate in a stable and level position.Fill the bucket with 6~7 litres of representative fresh SCC and let the sample stand still for about 1 minute (± 10 seconds)During the 1 minute waiting period pre-wet the inner surface of the cone and the test surface of the base plate using the moist sponge or towel, and place the cone in the centre on the 200 mm circle of the base plate and put the weight ring on the top of the cone to keep it in place. (If a heavy cone is used, or the cone is kept in position by hand no weight ring is needed)Fill the cone with the sample from the bucket without any external compacting action such as rodding or vibrating. The surplus concrete above the top of the cone should be struck off, and any concrete remaining on the base plate should be removed
59 Slump Flow Test Procedure After a short rest (no more than 30 seconds for cleaning and checking the moist state of the test surface), lift the cone perpendicular to the base plate in a single movement, in such a manner that the concrete is allowed to flow out freely without obstruction from the cone, and start the stopwatch the moment the cone looses contact with the base plate.Stop the stopwatch when the front of the concrete first touches the circle of diameter 500 mm. The stopwatch reading is recorded as the T50 value. The test is completed when the concrete flow has ceasedMeasure the largest diameter of the flow spread, dmax, and the one perpendicular to it, dperp, using the ruler (reading to nearest 5 mm). Care should be taken to prevent the ruler from bending.
60 Slump Flow Test Expression Of Results The slump flow spread S is the average of diameters dmax and dperp, as shown in Equation (1). S is expressed in mm to the nearest 5 mmThe slump flow time T50 is the period between the moment the cone leaves the base plate and SCC first touches the circle of diameter 500 mm. T50 is expressed in seconds to the nearest 1/10 seconds
61 Slump Flow Test Precision In accordance with ISO 5725, the repeatability r is defined as the difference between two consecutive test values by the same operator with the same apparatus that should be exceeded only once in 20 times, and reproducibility R is defined as the difference between two consecutive test values by different operators with different apparatus that should be exceeded only once in 20 timesBased on the inter-laboratory test organized in the EU-project “Testing-SCC” (GRD /G6RD-CT ) with 2 replicates and 16 operators from 8 laboratories, the values of repeatability and reproducibility of the slump flow spread and flow time T50 are listed in Table 1
64 L-Box Test Definition Apparatus The method aims at investigating the passing ability of SCC. It measures the reached height of fresh SCC after passing through the specified gaps of steel bars and flowing within a defined flow distance. With this reached height, the passing or blocking behavior of SCC can be estimatedApparatusTwo types of gates can be used, one with 3 smooth bars and one with 2 smooth bars. The gaps are 41 and 59 mm, respectivelySuitable tool for ensuring that the box is level i.e. a spirit levelSuitable buckets for taking concrete sample
66 L-Box Test Procedure Place the L-box in a stable and level position Fill the vertical part of the L-box, with the extra adapter mounted, with 12.7 liters of representative fresh SCCLet the concrete rest in the vertical part for one minute (± 10 seconds). During this time the concrete will display whether it is stable or not (segregation).Lift the sliding gate and let the concrete flow out of the vertical part into the horizontal part of the L-box.When the concrete has stopped moving, measure the average distance, noted as Δh, between the top edge of the box and the concrete that reached the end of the box, at three positions, one at the centre and two at each side
67 L-Box Test Expression Of Results Precision The passing ratio PL or blocking ratio BL is calculated using equation (2) or (2’), and expressed in dimensionless to the nearest 0.01PrecisionBased on the inter-laboratory test organised in the EU-project “Testing-SCC” (GRD /G6RD-CT ) with 2 replicates and 22 operators from 11 laboratories, the precision of the L-box passing or blocking ratio can be expressed by the following equationsorwhere Hmax = 91 mm and H = 150 − Δh
68 L-Box TestPrecisionr = – 0.463PL, with R2 = 0.996, when PL ≥ 0.65; and r = 0.18 when PL < (3)orr = 0.463BL – 0.011, with R2 = 0.996, when BL ≤ 0.35; and r = 0.18 when BL > (3’)andR = – 0.425PL, with R2 = 0.989, when PL ≥ 0.65; and R = 0.18 when PL < (4)R = 0.425BL – 0.029, with R2 = 0.996, when BL ≤ 0.35; and R = 0.18 when BL > (4’)where R2 is the square correlation coefficient.Some values are listed in Table 2 for convenience of use
71 J-Ring Test Definition Apparatus The J-ring test aims at investigating both the filling ability and the passing ability of SCC. It can also be used to investigate the resistance of SCC to segregation by comparing test results from two different portions of sample. The J-ring test measures three parameters: flow spread, flow time T50J (optional) and blocking step. The J-ring flow spread indicates the restricted deformability of SCC due to blocking effect of reinforcement bars and the flow time T50 indicates the rate of deformation within a defined flow distance. The blocking step quantifies the effect of blocking.ApparatusJ-ring with the dimensions as shown in Figure 6, where the positions for the measurement of height differences are also givenStraight rod for aligning the reference line in the measurement, with a length of about 400 mm and at least one flat side having the flexure less than 1 mm.
73 J-Ring TestProcedurePlace the cleaned base plate in a stable and level positionFill the bucket with 6~7 litres of representative fresh SCC and let the sample stand still for about 1 minute (± 10 seconds).Under the 1 minute waiting period pre-wet the inner surface of the cone and the test urface of the base plate using the moist sponge or towel, and place the cone in the centre on the 200 mm circle of the base plate and put the weight ring on the top of the cone to keep it in place. (If a heavy cone is used, or the cone is kept in position by hand no weight ring is needed).Place the J-ring on the base plate around the coneFill the cone with the sample from the bucket without any external compacting action such as rodding or vibrating. The surplus concrete above the top of the cone should be struck off, and any concrete remaining on the base plate should be removed
74 J-Ring TestProcedureCheck and make sure that the test surface is neither too wet nor too dry. No dry area on the base plate is allowed and any surplus of the water should be removed – the moisture state of the plate shall be ‘just wet’.After a short rest (no more than 30 seconds for cleaning and checking the moist state of the test surface), lift the cone perpendicular to the base plate in a single movement, in such a manner that the concrete is allowed to flow out freely without obstruction from the cone, and start the stopwatch the moment the cone loose the contact with the base plateStop the stopwatch when the front of the concrete first touches the circle of diameter 500 mm. The stopwatch reading is recorded as the T50J value. The test is completed when the concrete flow has ceased.lay the straight rod with the flat side on the top side of the J-ring and measure the relative height differences between the lower edge of the straight rod and the concrete surface at the central position (Δh0) and at the four positions outside the J-ring, two (Δhx1, Δhx2) in the x-direction and the other two (Δhy1, Δhy2) in the y-direction (perpendicular to x)
75 J-Ring Test Procedure Expression Of Results Measure the largest diameter of the flow spread, dmax, and the one perpendicular to it, dperp, using the ruler (reading to nearest 5 mm). Care should be taken to prevent the ruler from bendingNOTE For non-circular concrete spreads the x-direction is that of the largest spread diameterExpression Of ResultsThe J-ring flow spread SJ is the average of diameters dmax and dperp, as shown in Equation (6). SJ is expressed in mm to the nearest 5 mm
76 J-Ring Test Expression Of Results The J-ring flow time T50J is the period between the moment the cone leaves the base plate and SCC first touches the circle of diameter 500 mm. T50J is expressed in seconds to the nearest 1/10 secondsThe J-ring blocking step BJ is calculated using equation (7) and expressed in mm to the nearest 1 mm.
77 J-Ring Test Precisions Based on the inter-laboratory test organised in the EU-project “Testing-SCC” (GRD /G6RD-CT ) with 2 replicates and 16 operators from 8 laboratories, the values of repeatability and reproducibility of the J-ring flow spread and flow time T50J are listed in Table 6
79 V-Funnel Test Definition Apparatus The V-funnel flow time is the period a defined volume of SCC needs to pass a narrow opening and gives an indication of the filling ability of SCC provided that blocking and/or segregation do not take place; the flow time of the V-funnel test is to some degree related to the plastic viscosity.ApparatusV-funnel, as shown in Figure 7, made of steel, with a flat, horizontal top and placed on vertical supports, and with a momentary releasable, watertight opening gateStopwatch with the accuracy of 0.1 secondfor recording the flow timeStraightedge for levelling the concreteBuckets with a capacity of 12∼14 litresfor taking concrete sampleMoist sponge or towel for wettingthe inner surface of the V-funnel
80 V-Funnel Test Procedure Place the cleaned V-funnel vertically on a stable and flat ground, with the top opening horizontally positionedWet the interior of the funnel with the moist sponge or towel and remove the surplus of water, e.g. through the opening. The inner side of the funnel should be ‘just wet’.Close the gate and place a bucket under it in order to retain the concrete to be passedFill the funnel completely with a representative sample of SCC without applying any compaction or roddingRemove any surplus of concrete from the top of the funnel using the straightedge.Open the gate after a waiting period of (10 ± 2) seconds. Start the stopwatch at the same moment the gate opens
81 V-Funnel Test Procedure Expression Of Results Look inside the funnel and stop the time at the moment when clear space is visible through the opening of the funnel. The stopwatch reading is recorded as the V-funnel flow time, noted as tVDo not touch or move the V-funnel until it is emptyExpression Of ResultsThe V-funnel flow time tV is the period from releasing the gate until first light enters the opening, expressed to the nearest 0.1 second
82 V-Funnel Test Expression Of Results Based on the inter-laboratory test organised in the EU-project “Testing-SCC” (GRD /G6RD-CT ) with 2 replicates and 20 operators from 10 laboratories, the precision of the V-funnel flow time can be expressed by the following equationsthe precision of the V-funnel flow time can be expressed by the following equations:r = tV – 0.62, with R2 = 0.823, when 3 ≤ tV ≤ 15; and r = 4.4 when tV > 15 (8)andR = tV – 0.943, with R2 = 0.984, when 3 ≤ tV ≤ 15; and R = 6.6 when tV > 15 (9)where R2 is the square correlation coefficient.Some values are listed in Table 5 for convenience of use.
85 Orimet Test Definition Apparatus The Orimet flow time is the period a defined volume of SCC needs to pass a narrow opening (a tube narrowed by an orifice). The flow time of the Orimet test is to some degree related to the plastic viscosityApparatusOrimet, made of steel, with the tube of a length of 600 mm and an inner diameter of 120 mm. The orifice, which narrows the opening of the tube and shears SCC, is interchangeable; its diameter can be chosen according to the mixture composition and the criteria on SCC. Figure 8 shows the filling of the Orimet with a bucketStopwatch with the accuracy of 0.1 second for recording the flow timeStraightedge for levelling the concreteBuckets with a capacity of 10∼12 litres for taking concrete sampleMoist sponge or towel for wetting the inner surface of the Orimet
87 Orimet TestProcedurePlace the cleaned Orimet vertically on a stable and flat ground, with the top opening horizontally positioned and check whether the tripod is completely extendedWet the interior of the Orimet with the moist sponge or towel and remove the surplus of water, e.g. through the opening. The inner side of the Orimet should be ‘just wet’.Close the gate and place a bucket under it in order to retain the concrete to be passedFill the Orimet completely with a representative sample of SCC without applying any compaction or roddingRemove any surplus of concrete from the top of the Orimet using the straightedgeOpen the gate after a waiting period of (10 ± 2) seconds. Start the stopwatch at the same moment the gate opens
88 Orimet Test Procedure Expression Of Results Look inside the Orimet and stop the time at the moment when clear space is visible through the opening of the Orimet. The stopwatch reading is recorded as the Orimet flow time, noted as tOExpression Of ResultsThe Orimet flow time tO is the period from releasing the gate until first light enters the opening, expressed to the nearest 0.1 secondBased on the inter-laboratory test organised in the EU-project “Testing-SCC” (GRD /G6RD-CT ) with 2 replicates and 20 operators from 10 laboratories, the precision of the Orimet flow time (with the orifice 70 mm) can be expressed by the following equations
89 Orimet Test Expression Of Results and r = tO – 0.594, with R2 = 0.996, when 3 ≤ tO ≤ 15; and r = 6.6 when tO > (10)andR = tO – 0.28, with R2 = 0.947, when 3 ≤ tO ≤ 15; and R = 6.8 when tO > 15 (11)where R2 is the square correlation coefficient.Some values are listed in Table 6 for convenience of use.
91 Penetration Test Definition Apparatus The test aims at investigating the resistance of SCC to segregation by penetrating a cylinder with a given weight into the fresh SCC sample. If the SCC has poor resistance to segregation, the cylinder will penetrate deeper due to the less amount of aggregate in the upper layer of the sample. Therefore the penetration depth indicates whether the SCC is stable or notApparatusPenetration apparatus, as illustrated in Figure 9, consisting of a frame, slot and screw, reading scale and penetration head. The penetration head is assembled with an aluminium cylinder and rod. The rod should be able to move inside slot, as freely as possible. The inner diameter, height and thickness of the cylinder are 75 mm, 50 mm and 1 mm, respectively. The total weight of the penetration head is 54 g.
92 Penetration TestApparatusBucket with a capacity of 10~12 litres
93 Penetration Test Procedure Place the bucket in a stable and level positionFill the bucket with (10 ± 0.5) litres of representative fresh SCC and let the sample stand still for 2 minutes ± 10 secondsNOTE Care must be taken to avoid segregation caused by external impacts2 minutes after filling of the bucket, locate the penetration apparatus on the top of the bucket, adjust the penetration cylinder until it just touches the upper surface of the concrete, and then let the cylinder penetrate freely into concreteAfter the stabilisation of the cylinder (generally < 15~20 sec), the penetration depth of the cylinder head is recorded from the scale. Measure the penetration depths at the centre (noted as P1) and two sides (noted as P2 and P3) of the width of the bucketNOTE The duration of the three measurements should be less than 3 minutes
94 Penetration Test Expression Of Results Precisions The penetration depth P is the average value of the three measurements, rounded to 1 mm.PrecisionsBased on the inter-laboratory test organised in the EU-project “Testing-SCC” (GRD /G6RD-CT ) with 2 replicates and 22 operators from 11 laboratories, the precision of the penetration depth can be expressed by the following equationr = R = 0.59 P + 1.7, with R2 = 1, when P ≤ 17; and r = R = 12 when tO > 17 (12)where R2 is the square correlation coefficient.Some values are listed in Table 7 for convenience of use.