Field live Slump Test of Concrete | Slump Test procedure of Concrete | Slump Test

The concrete slump test measures the consistency of fresh concrete before it sets. It is performed to check the workability of freshly made concrete, and therefore the ease with which concrete flows. It can also be used as an indicator of an improperly mixed batch. Slump Test: • It is the most common method for measuring the workability of freshly mixed concrete. • It is a field test. It can also be performed in laboratory. It is suitable for medium to high workability of concrete. • It is not suitable for very wet or very dry concrete. It is also not suitable for concrete containing aggregates larger than 40 mm. • Uniformity of the concrete regarding workability and quality aspects can be assessed from batch to batch by observing the nature in which the concrete slumps. • Procedure: • This test is carried out with a mould called slump cone, which is in the form of the frustum of a cone, having top diameter 10 cm, bottom diameter 20 cm and height 30 cm. • The detailed procedure is as under: • Clean the internal surface of the mould and apply oil. • Place the mould on a smooth horizontal non- porous base plate. • Fill the mould with the prepared concrete mix in 4 approximately equal layers. • Tamp each layer with 25 strokes of the rounded end of the tamping rod (of steel 16 mm diameter and 60cm long and rounded at one end) in a uniform manner over the cross section of the mould. For the subsequent layers, the tamping should penetrate into the underlying layer. • Remove the excess concrete and level the surface with a trowel. • Clean away the mortar or water leaked out between the mould and the base plate. • Raise the mould from the concrete immediately and slowly in vertical direction. • Measure the slump as the difference between the height of the mould and that of height point of the specimen being tested. • The slump (Vertical settlement) measured shall be recorded in terms of millimeters of subsidence of the specimen during the test. • When the slump test is carried out, following are the shape of the concrete slump that can be observed: • True Slump: If the concrete slumps evenly all round, it is called true slump. True slump is the only slump that can be measured in the test. The measurement is taken between the top of the cone and the top of the concrete after the cone has been removed. • Zero Slump: If there is no slump, it is called zero slump. Zero slump is the indication of very low water-cement ratio, which results in dry mixes. This type of concrete is generally used for road construction. • CollapsedSlump: If the concrete collapses, it is called collapsed slump. This is an indication that the water-cement ratio is too high, i.e. concrete mix is too wet or it is a high workability mix, for which a slump test is not appropriate. • Shear Slump: If one half of the cone slides down, it is called shear slump. The shear slump indicates that the result is incomplete, and concrete to be retested. #SlumpTestofConcrete #SlumpTest #ConcreteSlumpTest #SlumpTestprocedure #Concretetesting #Concretetechnology