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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Some useful methods for enhancing ground condition

The civil engineers should be well aware with the ground improvement methods since the stability of the structure mainly depends on the good quality of soil.

The following methods are undertaken for the enhancement of the ground :-

Replacement of soil, Precompression of soil, Densification of soil, Reinforcement of Techniques, Grouting techniques, Stabilization using admixture, Geo textiles, Electro osmosis method.

Replacement of soil: Under this method, the unacceptable soil is uncovered and they are replaced with compacted fill. It is a standard method to rectify the issues with compressible soils. Evacuation and substitution is normally judicious just over the ground water table.

Pre-compression of soil: It is particularly suitable in soft clay and sandy or mud soils since the static weight of the fill motivates them to consolidate, thus making both settlement and strength properties superior.

Pre-compression offers the following benefits:

1. The method provides a long track record of success.
2. Any grading contractor will be able to execute the work.
3. The cost is moderately low, provided that soil for preloading is instantly available.

Densification of soil: The stability and firmness of the soil remains greater when the particles are stuffed in a dense configuration. It is very suitable for making the characteristics of the soil better.

It can be done in the following manners : VIBRO TECHNIQUES and DYNAMIC COMPACTION

Reinforcement of Techniques: The shear strength under the structures is raised with the utilization of stone columns. The method comprises of developing vertical holes in ground which are stuffed with compacted crushed stone, gravel and sand or a mixture.

Grouting Methods

PERMEATION GROUTING - Stopping leaks in below-grade structures, Stopping leaks in below-grade utilities, Excavating support of non-corrosive soils

JET GROUTING: Jet grouting applies a special pipe that is provided with horizontal jets to inject grout into the soil at high pressure.

Stabilization with admixture: SOIL STABILIZATION: It is the method of engineering characteristics of soil with the inclusion of some binding agents to join the soil particles. Soil stabilization is categorized as follow :-

1. Mechanical stabilization
2. Chemical stabilization

Geo textiles: Geotextiles stand for permeable fabrics manufactured products and there are other materials like polyester, poly-ethylene, polypropylene and poly vinyl chloride, nylon, fiber glass and different mixtures of these.

Electro osmosis method: The electro osmosis method is utilized to improve the shear strength and decrease the compressibility of soft clay and sandy soils underneath foundation, electro osmosis with or without electrochemical hardening is taken into consideration only for special occasions where the substitute of piling cannot be embraced.



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Published By
Rajib Dey
www.constructioncost.co
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