Benefits of fresh concrete to be vibrated

Fresh concrete that should be vibrated provides huge benefits. Freshly placed, unconsolidated concrete normally contains full of entrapped air bubbles. Concrete can attain a greater compressive strength and density with least air content mechanically i. e. with the help of high frequency (fast, repetitive) vibrations.

Thus, the concrete fulfill the present needs with regards to strength and density. The vibrator produces high frequency vibrations which are delivered to the components of the fresh concrete.

• Frictional forces among individual particles are significantly minimized.
• A flow process is formed.
• Air bubbles, excess water and paste are congested via capillary action and surface tensions are discharged and evaded to the surface.

Benefits of concrete vibration

• Superior density and consistency
• Superior compressive strength
• Superior durability (e. g. de-icing salt)
• Perfect bond with rebar, specifically in thickly reinforced sections

• Greater bond among the individually “wet” on “wet” placed layers
• Better quality exposed (fair-faced) surfaces
• Utilization of drier mixtures results in necessitating less cement.

Recognize your effective compaction diameter: For practical uses and as rule of thumb, approximate value should be taken for the operating diameter i.e. 10 times the vibrator head housing diameter.

Proper spacing should be retained while compacting large surfaces.

Proper spacing should be maintained while vibrating fresh concrete in walls.

Internal vibrators with dia (Ø) 30 (1.2”), 38 (1 ½”) and 45 mm (1.8”) should not be utilized because of poor or non-existing overlapping of the effective compaction Ø. It will result in producing a defective or inexpensive vibration method.

For superior effective compaction Ø and for more suitable, inexpensive compaction (less insertions, less time) preferably the following should be utilized :-

• Vibrators with diameters 57 or 65 mm, on the condition that the rebar allows it.
• The concrete will be compacted flawlessly due to the overlapping.

It is found that consistently and horizontally extended layers offer the superior outcomes in concrete compaction with approximately 50 cm (20”) thickness.



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Published By
Rajib Dey
www.constructioncost.co
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Applications and advantages of Slag Cement in concrete construction

Slag cement stands for a hydraulic cement that is developed when granulated blast furnace slag (GGBFS) is crushed by maintaining proper delicacy and utilized to substitute a part of portland cement. It is applied as an independently batched cementitious materials.

It belongs to a restored industrial by-product concerning an iron blast furnace. It mainly contains calcium and aluminum silicates.

Molten slag deflected from the iron blast furnace is chilled instantly. It forms glassy granules that offer required reactive cementitious characteristics when crush into cement fineness.

As soon as the slag is chilled and crushed to an utilizable fineness it is preserved and transported to suppliers. Slag cement is extensively used in ready-mixed concrete, precast concrete, masonry, soil cement and high temperature resistant building products.

The slag cement can improve the functioning of concrete for a long period as well as facilitates the designers to minimize the environmental footprint of concrete whereas assuring superior performance and better stability.

Given below, the various advantages of slag cement application:

1. Superior functionality
2. Simpler placeability and finishability
3. Greater long-standing compressive and flexural strengths
4. Lowered permeability
5. ASR mitigation properties
6. Superior stability and resilience
7. More uniform performance
8. Lighter color

Specifications and Grade:

Grade 80: Slag containing a low activity index

Grade 100: Slag with a moderate activity index

Grade 120: Slag with a high activity index

Application & dosage (% by weight) of slag

Outside flatwork ≤35%
General application 35 to 50%
Mass concrete 60 to 80%

Sulfate resistance
Type II equivalent ≥ 35%
Type V equivalent ≥ 50%
Marine/chemical/heat >50%<80%

The slag cement is used in diverse ways which range from ternary mixtures and soil stabilization etc.




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Published By
Rajib Dey
www.constructioncost.co
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Distinctive Construction Joints Details and Spot for Beams and Columns

During the need of concreting termination for the day or more than 30 minutes or so; construction joints in RCC beams and columns are necessary. In such circumstances, regular construction joints shall be provided for the reason that bond is maintained between set concrete and fresh concrete properly.

The provided images below portray proper process of construction joints to be provided in columns, beams and beam-column junction.

1. Construction Joints in Column

The figure below highlights accurate procedure of supplying construction joint in column. One thing should be kept in mind that smooth or tilted surface is not appropriate for providing construction joint in column. With parts of visible coarse aggregates the column’s top surface should be rough.

2. Construction Joints in Beams and Beam-Column Joint

The figure as following give you an idea about the typical construction joint to be provided in beams and beam column joints.

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Published By

Rajib Dey

www.constructioncost.co

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