Do we reject concrete which exceed lacks its slump requirement?

When the concrete slump is more than the maximum limit, and concrete durability is of high importance, it is better to reject the concrete.

What happens if concrete slump is too high?

“The higher the slump the more workable the concrete. If the slump of concrete is too low it won’t be 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”.

What is the minimum slump of concrete that can be used on site?

What is the ideal value of slump? Answer 1 In case of a dry sample, slump will be in the range of 25-50 mm that is 1-2 inches. But in case of a wet concrete, the slump may vary from 150-175 mm or say 6-7 inches.

How do you reduce slump in concrete?

Adding just 1 gallon of water per cubic yard can: • Increase slump 1 inch • Decrease compressive strength 150 to 200 psi • Waste about 1⁄4 bag of cement • Increase shrinkage by 10\% But water isn’t the only way to adjust slump. Consider adding a water reducer or superplasticizer at the site to increase slump.

What are the basis of rejection for fresh concrete?

Strength
Strength is usually the basis for acceptance or rejection of the concrete in the structure.

Does slump affect concrete strength?

It shows the flow and overall workability of freshly mixed concrete. 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.

Which slump is better for concrete?

Very dry mixes having slump 0 – 25 mm are typically used in constructing pavements or roads, low workability mixes having slump 10 – 40 mm are typically used for foundations with light reinforcement, medium workability mixes with slump 50 – 90 mm, are typically used for normal reinforced concrete placed with vibration.

What does high slump concrete require?

High slump or “flowing” concrete mixes are economical ready mix products that allow maximum flowability without sacrificing strength by adding water at the jobsite. These high slump, high strength properties are attained through the use of high range water reducing admixtures (superplasticizers).

What is the ideal slump Why?

In a true slump concrete just subsides shortly and more or less maintain the mould shape. This type of slump is most desirable. Zero Slump: If concrete maintains the actual shape of the mould, it is called zero slump which represents stiff, consistent and almost no workability.

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.

What factors affect slump?

Which factors influence the concrete slump test:

• Material properties like chemistry, fineness, particle size distribution, moisture content and temperature of cementitious materials.
• Size, texture, combined grading, cleanliness and moisture content of the aggregates,