Table of Contents
- 1 What does the slump test on concrete determine?
- 2 How is slump related to workability?
- 3 What affects the slump of concrete?
- 4 How does slump affect concrete strength?
- 5 In which concrete slump test is used to for testing properties of fresh concrete?
- 6 What are the limitations of slump test?
- 7 What happens when concrete slump is too high?
- 8 How does a high slump or low slump affect concrete?
What does the slump test on concrete determine?
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.
Concrete workability, quantified by concrete slump, is an important property of a concrete mixture. Concrete slump is generally known to affect the consistency, flowability, pumpability, compactibility, and harshness of a concrete mix.
What happens if concrete fails the slump test?
If the slump test fails, then we should reject that concrete. If the water-cement ratio is high, then the workability of concrete is increased. Still, the durability of concrete is decreased due to excessive water, which forms voids in the concrete and reduce the strength of the concrete.
What affects the slump of concrete?
Even with no change in water content, other variations in aggregate grading, fines content (cement and supplementary cementitious materials), entrained air content, and especially water-reducing admixtures, can have a major effect on slump and slump loss.
How does slump affect concrete strength?
Slump is the measure of concrete consistency and fluidity. It shows the flow and overall workability of freshly mixed concrete. Simply put, the higher the slump, the wetter the mix. Slumps that are above average will cause reduced strength, durability, and permeability of the concrete.
How do you determine a slump?
Place a straight edge, preferably the tamping rod, across the slump mold base, with one end suspended over the pile of concrete. Using a tape or ruler, measure the distance from the bottom of the straight edge to the displaced center of the slumped concrete. Record your results to the nearest 1/4 of an inch.
In which concrete slump test is used to for testing properties of fresh concrete?
Slump test is one of the tests that are performed in the fresh state concrete at the site once the concrete truck is arrived. Slump test is carried out in accordance with ASTM C143 in US and EN 12350-2 in Europe. And other countries will define the slump test procedures according to their own standards.
What are the limitations of slump test?
Limitation of Slump Test It is not suitable for a concrete in which maximum size of aggregate exceeds 40 mm. There are chances of many shapes of slump to occur and it is difficult to decide which is the correct value. The slump occurs only in case of plastic mixes.
Why do Slump tests fail?
For concrete with a high slump value, the test may be repeated since improper test procedure may have caused the failure, or the concrete in the mixer should be allowed to revolve for a maximum of 10 minutes to see whether the concrete falls within the specified slump range.
What happens when concrete slump is too high?
Simply put, the higher the slump, the wetter the mix. Four-inch (4”) slump is very common with normal weight concrete and is a good for pumping. Slumps that are above average will cause reduced strength, durability, and permeability of the concrete.
How does a high slump or low slump affect concrete?
Slump is a measurement of the workability or consistency of concrete. The higher the slump, the more workable the concrete. If the slump of concrete is too low, it won’t shape very easily. If it is too high, you run the risk of having the gravel, sand and cement settle out of the mixture, making it unusable.