What Is Slump Test – Procedure , Result & Calculation
WHAT IS THE CONCRETE SLUMP TEST?
Concrete is a versatile and widely used construction material known for its strength and durability. However, achieving the desired consistency in concrete is crucial to ensure its workability and performance. One of the most common methods used to measure the consistency of a concrete batch is through a test known as the concrete slump test. This test provides valuable insights into the flow characteristics of the concrete and helps identify any potential issues or defects before the concrete is used in construction projects.
Factors affecting Slump Cone Test
The following factors influence concrete Slump value:
1. Quality of Fine aggregate, Coarse aggregate, its texture, grading size, moisture content, and shape of it.
2. water-cement (w/c) ratio can also affect the slump value of concrete
3. Air content and void ratio of concrete.
4. Use of various types of admixtures such as Superplasticizer, Plasticizer admixture, and the sequence of them mixing.
5. Time is also a crucial factor in concrete mixing.
Equipments Required for Concrete Slump Test
1. Mold for slump test i.e. The equipment used for the slump cone test includes a slump cone, a non-porous base plate, a measuring scale, and a tamping rod.
2. The test mold is in the shape of a frustum of a cone with a height of 30 cm.
3. Slump cone with a bottom diameter of 20 cm and a top diameter of 10 cm.
4. The tamping rod is of steel 16 mm diameter and 60cm long and rounded at one end.
Procedure for Concrete Slump Cone Test
1.At frist Clean the internal surface of the mould than apply oil.
2. Position the mold on a smooth, horizontal, non-porous base plate.
3. Fill the mould with the prepared concrete mix in 4 approximately equal layers.
4. Compact each layer by tamping with 25 strokes using the rounded end of the tamping rod. Tamp uniformly across the cross-section of the mold. Ensure that the tamping penetrates into the underlying layer for subsequent layers.
5. Remove the excess material and level the surface with a trowel.
6. Clean away the mortar or water that leaked out between the mold and the base plate.
7.Lift the mold from the concrete immediately and slowly in a vertical direction.
8. Measure the slump by calculating the difference between the height of the mold and the highest point of the tested specimen.
Slump Value Observation:
The slump, which refers to the vertical settlement, should be measured and recorded in millimeters as the subsidence of the specimen during the test.
Results of Slump Test on Concrete
The slump for the given sample is _______ mm. When conducting the slump test, various shapes of concrete slumps can be observed, including the following.
1. True Slump
The true slump is the only type of 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, as shown in the images.
2. Zero Slump
Zero slump is an indication of a very low water-cement ratio, resulting in dry mixes. This type of concrete is frequently utilized in road construction projects.
3. Collapsed Slump
This indicates that the water-cement ratio is too high, meaning the concrete mix is excessively wet or has high workability. In such cases, a slump test is not suitable.
4. Shear Slump
The shear slump indicates an incomplete result, requiring the concrete to be retested.
What is a slump test?
A slump test is a widely used method in the construction industry to evaluate the consistency and workability of freshly mixed concrete.
1. Slump Value is 0 – 25 mm Used for Road Construction
2. Slump Value is 10 – 40 mm Used for Foundations with light reinforcement
3. Slump Value is 50 – 90 mm Used for Normal reinforced concrete placed with vibration
4. Slump Value is > 100 mm Used for High workability concrete