Concrete centre Sampling - BRMCA

1 A practical guide for site personnel Site Sampling and testing of Concrete Cubes have a vital role to test that the Concrete strength meets the specification requirement. However, the cube results will be meaningless unless the Sampling and testing procedures given here are followed. Sampling depth not just the top part. The size of sample taken should be 11/2 times the estimated volume required Complete a Sampling certificate and record which Sampling method was used. will be applicable for Concrete sampled by this method. Scoopfuls must be taken through the moving stream for testing. The standard composite sample Sampling the whole width and depth. Let very first Concrete go The alternative spot sample BS EN 12350-1. BS EN 206-1:2000, clause Let very first Concrete go To ensure it is representative of the whole truck load a Take a scoopful from part 1 Take six scoopfuls from the next m 3.

2 Standard sample consists of scoopfuls taken from four Take a scoopful from part 2 Do not use this method to make cubes Take six scoopfuls after the first m has been discharged 3. different parts of the load and collected in buckets. Take a scoopful from part 3 For an early check on the consistence of Concrete delivered Scoopfuls must be taken through the moving stream, Take a scoopful from part 4 in a truck mixer, this alternative method of spot Sampling as the load is discharged, Sampling the whole width and Let the last Concrete go from the initial discharge may be used. Additional tolerances The Step 1. slump test BS EN 12350-2. Step 9. Step 4 Step 6 There are three kinds of slump Empty the Sampling buckets onto the Ensure the slump cone and base plate are Top up if necessary Lay the rod across the upturned slump cone mixing tray clean and damp Use the rod with a Scrape each bucket clean Place the metal plate on solid level base sawing and rolling Measure the distance between the away from vibration or other disturbance motion to strike the underside of the rod and the highest point True Shear Collapse Step 2 Place the cone on the plate and stand on Concrete level with the of the Concrete the true slump Thoroughly remix the the foot-pieces top of the cone Record the distance to the nearest 10 mm sample.

3 Shovelling into a heap Step 5 Step 7 Check and record the kind of slump You will need this equipment Turn the heap over to Fill the cone in three equal Carefully clean off spillage from sides and If the slump isn't true, (always clean and dry the equipment after use). take a new sample and Small scoop Sampling and testing form another depth layers baseplate whilst maintaining foot pressure repeat the test Slump rod certificates Do this three times Use the standard slump rod Step 8 If the second slump isn't Square-mouthed Steel rule Rod each layer 25 times Carefully lift the cone true, get advice shovel Damp cloth Step 3 Spread the blows evenly straight up and clear, Complete the Sampling Mixing tray Sampling scoop Flatten the final heap by repeatedly Heap the Concrete above the top of the cone 5toanda count of between and testing certificates Buckets or Slump cone and rigid digging-in the shovel vertically before rodding the third layer over the area 10 seconds wheelbarrow metal plate Lift the shovel clear each time Make sure the rod just penetrates the layer below The flow test BS EN 12350-5.

4 First find a suitable location for the flow table. Step 3 Step 4 Step 7 Record the flow value as d1 + d2 divided by 2. It must be placed on a firm, flat and level surface. It may be necessary to prepare an Ensure the mould and Carefully clean off spillage from around the Slowly lift the table Report any segregation which may have table are clean and damp mould and table top top by the handle occurred around the sample edge area for the table. Place the mould on the Step 5. until it reaches the upper stop Complete the Sampling and testing certificates Step 1 centre of the table and stand on the foot-pieces Wait 30 seconds from Allow the table to fall freely Empty the Sampling buckets onto the striking off Repeat this cycle to give a total of 15 drops You will need this equipment mixing tray Fill the mould in two Carefully lift the mould Each cycle should take about 4 seconds (always clean and dry the equipment after use).

5 Layers, tamping each Scrape each bucket clean layer ten times with the tamping bar straight up and clear to Step 8. Sampling scoop Tamping bar Step 2 If necessary add more Concrete to fill the a count of between Small scoop Brush and Thoroughly remix the sample as described top layer 3 and 6 seconds Measure the largest dimension of Concrete Damp cloth and mould oil plastic sheeting Curing tank for the slump test Use the tamping bar to strike the top layer Step 6 spread in two direc- Buckets or Hide hammer level with the top of the mould Stabilise the flow table by standing on the toe board at the front of the table tions, parallel to the wheelbarrow Mixing tray table edges Making cubes StepBS2EN 12390-2 Step 3. Collect a composite sample to the standard method described above. Concrete sampled Fill the mould with After tamping of each layer, tap the sides of the mould with the hide hammer until Numberdetails the moulds for identification and You will need this equipment in 50 mm layers Concrete record (always clean and dry the equipment after use).

6 Using the alternative spot method must not large bubbles of air cease to appear on the using the tamping bar, Sampling scoop Maximum/minimum be used to make cubes. compact the Concrete with surface and the holes left by the tamping Step 5 thermometer Small scoop Step 1 no fewer than 25 tamps bar are closed Cover each mould with a damp cloth and plastic sheet Damp cloth and Square-mouthed shovel Check that the moulds are clean and lightly for each of the two layers Step 4 plastic sheeting Felt tip pen or crayon oiled with all bolts tightened so that there in a 100 mm mould and Remove surplus Concrete Store_. inside at room temperature 0. (15 25 C) on top of the curing tank Buckets or Cube moulds will be no leakage no fewer than 35 tamps wheelbarrow and smooth over with Spanner Ensure that the correct halves of the for each of the three layers in a 150 mm mould a float Protect the cube moulds at all times from Tamping bar Mixing tray moulds are used and that the corner lifting high and lowtemperature (especially pins are correctly located For very high workability Concrete you may Wipe clean the mould sub-zero temperatures) and drying winds Brush and mould oil Damp cloth edges Curing tank Sampling .

7 Cube making Thoroughly remix the sample as described not need the minimum number of tamps Complete the Sampling and cube making Hide hammer and storage certificates for the slump test certificates Storing cubes BS EN 12390-2. The cubes should be removed from the moulds Lift off carefully Step 4 Check the temperature range daily using the maximum/minimum thermometer at between 16 and 72 hours after casting. Remember new cubes Place the cubes in the curing tank Step 1 easily damaged are Clean and reassemble the moulds Keep a record of the readings unless handled carefully Record the maximum/minimum overnight Step 5 Step 6. storage temperatures on the certificate Step 3 For despatch to test laboratory, wrap the Step 2 Mark each cube with its Check that the water temperature is wet cubes in damp cloths, and then plastic controlled at 200C 0C.

8 2 and the cubes are identification number on two of its bags and pack in trays Slacken all nuts cast sides covered by water Part the sides of the mould, tapping gently Make sure the power supply is not Attach the certificates for Sampling , switched off day or night testing, cube making and storage to the with the hide hammer package along with the order for testing SAFETY alkali burns some of which, don't cause If Concrete does contact your skin, wash Lifting Fresh Concrete is heavy, with a The first rule of working with Concrete is pain immediately or dermatitis. immediately and thoroughly with clean barrow load weighing over 100 kg. So water. If your eyes are affected, seek medical to be protected. The longer the skin is in contact with the help immediately. carrying just a small volume may cause physical injury. Follow Health & Safety Ensure that the personnel are wearing Concrete , the worse the injury will be.

9 So, adequate safety equipment. protect yourself by wearing safety goggles, The water in the curing tank is highly regulations so that you can place, compact and finish the work before it All advice or information from The Concrete centre is intended for use in the UK only by those who will evaluate the significance and limitations of its contents and take waterproof gloves, a sturdy jacket, alkaline so ensure that gloves are used when responsibility for its use and application. No liability (including that for negligence) for any loss resulting from such advice or information is accepted by The Concrete centre or If fresh Concrete touches the skin, it can cause waterproof trousers and long boots. handling cubes in the tank. sets without straining yourself. its subcontractors, suppliers or advisors. Readers should note that the publications from The Concrete centre are subject to revision from time to time and should therefore ensure that they are in possession of the latest version.

10 British Ready Mixed Concrete Association and published by The Conrete centre on behalf of BRMCA . Produced and printed by The Book on the Wall Company, Kent Edited by A F G Lewis TCC/03/39 May 2008.