--- title: "Workability and slump test procedure" subject: "Concrete Technology and Masonry Structure" chapter: 3 key: "semester_5/concrete_technology_and_masonry_structure:slump-test-procedure" source: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/slump-test-procedure site: BCT Engineering --- # Workability and slump test procedure Concrete Technology and Masonry Structure · Chapter 3: Mix design of concrete and property of green concrete - Asked in: 2074 Ashwin, 1+3 marks - Video: [Slump test full procedure | concrete test | practical live on site](https://www.youtube.com/watch?v=y5AH9IQycvI) — Civil Site visit - Page: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/slump-test-procedure - Whole chapter: https://www.bctengineer.com/md/semester_5/concrete_technology_and_masonry_structure/chapter-3 ## Question Define workability and write down the procedure for performing the slump test. ## Short answer Workability is the ease of mixing, placing, compacting and finishing concrete without segregation. Slump test: clean cone on base plate, fill in 4 layers, each tamped 25 times with rod, strike off, lift cone slowly in 5-10 seconds, measure vertical subsidence to nearest 5 mm. Test completed within 2 minutes. ## Answer **Workability** is the ease with which concrete can be mixed, placed, compacted and finished without segregation (IS 6461 Part 7). #### Slump test procedure (IS 1199; IS 7320) **Apparatus**: slump cone (frustum) of 300 mm height, 200 mm bottom and 100 mm top internal diameter; tamping rod 16 mm dia, 600 mm long with bullet end; base plate (non-absorbent, smooth); scale. **Procedure** 1. Clean the mould and place it on a smooth, horizontal, non-absorbent base plate; hold it down with the foot pieces. 2. Fill the cone in **four layers**, each about one-quarter of the height; tamp each layer with **25 strokes** of the rod, uniformly distributed, penetrating into the layer below. 3. After the top layer, strike off the surface level with the top of the cone. 4. Lift the cone vertically slowly (in 5-10 seconds) without any twisting. 5. Measure the **slump**, the difference between the height of the mould and the height of the highest point of the subsided concrete, to the nearest 5 mm. 6. Complete the test within 2 minutes of sampling; if the concrete shears off or collapses, the test is repeated. Recommended slump (IS 456 cl. 7.1): 25-75 mm for lightly reinforced sections in slabs, beams, walls and columns; 50-100 mm for heavily reinforced sections; 75-100 mm for trench fill, etc. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. In the standard slump test, the cone is filled in how many layers and with how many tamping strokes each? A. 4 layers, 25 strokes B. 3 layers, 25 strokes C. 4 layers, 35 strokes D. 5 layers, 15 strokes Answer: A. IS 1199 requires four layers, each tamped 25 times. (Key point: Layers and tamping) 2. How should the cone be lifted? A. Quickly with a slight twist B. Vertically and slowly in 5-10 seconds, without twisting C. Sideways in 1 second D. After 5 minutes of rest Answer: B. The cone is lifted vertically and slowly (5-10 s) without twisting so the concrete is not disturbed. (Key point: Cone lifting) 3. How is the slump measured? A. Height of the cone B. Diameter of the spread concrete C. Difference between mould height and the highest point of subsided concrete D. Lowest point of the subsided concrete Answer: C. Slump is the mould height minus the height of the highest point of the subsided concrete. 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