How bubble deck technology is used in construction work

Bubble Deck belongs to the original combination method of connecting air, steel and concrete in two-way structural slab. Hollow plastic balls is embedded into the slab and reinforced with steel. The end result eliminates up to 35% of concrete that contains carrying effect at the time of restoring the two-way span strength. It can be used with most of the buildings particularly open floor design : educational, commercial, hospital and other organizational buildings.

Bubble Deck contains the following properties :-

Shear strength - 80% of solid deck slab
Deflection - Similar to solid slab
Weight - 40% below solid slab
Fire Resistance – 65% of solid slab

Bubble Deck slab belongs to a biaxial voided concrete slab in which high density polythene hollow sphere substitute the incompetent concrete in the middle of concrete slab.

Materials for building up the bubble deck

Steel: The steel reinforcement of MS or HYSD is applied.

Plastic Sphere: Void sphere formed with recycled high density polyethylene. It contains adequate strength & rigidity. It does not make any reaction.

Concrete: The concrete is formed with standard Portland cement with highest aggregate size of ¾ inch.

Bubble Deck Manufactured Components: It stands for a structural vacuumed smooth slab system that reduces dead weight of a floor slab by 33% facilitating longer span among column supports and forms an entire range of other cost and construction benefits.

The system acts as an alternative of all other supporting structure like beams or walls. The entire floor slab extents in two directions directly into pre-cast or in-situ reinforced concrete column.

Benefits of Bubble Deck:

Structural:
a. Less weight
b. No beams are necessary
c. Only few columns are essential
d. Make your choice for shape
e. Bigger Span

Construction
a. Fewer work on job site
b. Light weight, less equipment is necessary
c. Simple and does not require heavy jobsite work

Economy:
a. Huge savings for materials (slabs, beams, columns, foundation), up to 50%
b. Needs fewer carrying cost
c. Requirement of concrete is reduced up to 35%
d. Lower workforce, no carpentry, no beams and workers with less skill can be employed

Environmental:
a. Less material consumption (cement, aggregate, steel)
b. Less energy consumption (throughout production, transportation and lifting on construction site)



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Published By
Rajib Dey
www.constructioncost.co
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Advantages of microsillica in concrete

Microsilica alias silica fume or condensed silica fume stands for is a mineral admixture that is formed with very fine solid glassy spheres of silicon dioxide. Most microsilica particles remain under 1 micron (0.00004 inch) in diameter, normally 50 to 100 times finer as compared to average cement or fly ash particles. Microsilica belongs to a by-product of the industrial manufacture of ferrosilicon and metallic silicon in high-temperature electric arc furnaces.

Microsilica may be suitable in managing heat formation in mass concrete. It can also be combined with fly ash to provide superior result.

If pozzolanic materials are integrated with concrete, the existent silica in these materials makes a reaction with the calcium hydroxide produced throughout the hydration of cement and develops supplementary calcium silicate hydrate (C – S – H) that enhances the strength and the mechanical properties of concrete.

Types of Microsilica: Microsilica is categorized as follow -

1. Powdered microsilica, 2. Condensed microsilica, 3. Slurry microsilica

Impacts of Microsilica on Concrete

1. Fresh Concrete

a. It decreases the scope of segregation, so it is applied as pumping aid.
b. It almost reduces bleeding, as a result finishing work commences before time.
c. Workability and uniformity of concrete reduces.

2. Hardened Concrete: The inclusion of microsilica enhances the following characteristics of hardened concrete -

a. Improves compressive strength that leads to improve flexural and tensile strength.
b. Bond strength
c. Abrasion resistance
d. Lessens permeability; consequently, it safeguards reinforcement steel against corrosion.
e. Impact and cavitations resistance.
f. Sulphate Resistance
g. Heat Reduction
h. Chemical Resistance

Properties of Microsilica:

1. Microsilica belongs to a grey; almost white to black powder.
2. Spherical particles remain under 1mm in diameter.
3. The mass density of microsilica is dependent on the degree of densification and differs from 130 to 600 kg/m3.
4. The specific gravity of microsilica differs among 2.2 to 2.3

Benefits:

a. Minimizes thermal cracking resulting from the heat of cement hydration.
b. Enhance the strength to resist against sulphate and acidic waters.
c. Minimizes the growth of temperature in preliminary stage.
d. Silica fume is cheap; therefore, it is inexpensive.
e. It minimizes the entire slab weight and cost.
f. Inclusion of microsilica reduces efflorescence caused by the refined pore structure and increased consumption of the calcium hydroxide.



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Published By
Rajib Dey
www.constructioncost.co
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How concrete strength is impacted with different factors

The strength of concrete is impacted by various factors. The details are given below :-

Concrete porosity: Air and water are the useful substances to fill up voids in concrete. Air voids belong to pores in concrete. When concrete is blended it contains air trapped in the mix. The vibrators are used to clear out the air at the time of pouring walls.

If the concrete is less porous, it’s strength will be increased and calculated with compressive strength. The most crucial source of porosity in concrete refers to the proportion of water to cement in the mix, called the ‘water to cement ratio’.

Factors water/cement ratio: It is described as the mass of water divided by the mass of cement in a mix. As for instance, in a concrete mix if there are 400kg cement and 240litres(=240kg) of water, the water/cement ratio will be 240/400=0.6. The water cement ratio is shortened as ‘w/c ratio’ or just ‘w/c’. In mixes where the w/c is in excess of roughly 0.4, all the cement can, in theory, react with water to develop cement hydration products. If the w/c ratios are greater, it follows that the space occupied by the supplementary water over w/c=0.4 will persist as pore space filled with water, or with air when the concrete becomes dry.

As a result, when the w/c ratio become higher, the porosity of the cement paste in the concrete also upsurges. With the higher porosity, the compressive strength of the concrete will reduce.

Stability of aggregate: It is inevitable that when the aggregate in concrete is feeble, the concrete also becomes feeble. Rocks like chalk that contain low intrinsic strength, are not appropriate to be utilized as aggregate.

Aggregate-paste bond: The strength of the bond among the paste and the aggregate is vital. When no bond exists, the aggregate practically reproduces a void and the strength of concrete is decreased.

Cement-related parameters: Various parameters pertaining to the formation of the individual cement minerals and their ratios in the cement can impact the rate of strength growth and the final strengths gained.

To get more information, click on the following link www.onlinecivilforum.com

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Published By

Rajib Dey

www.constructioncost.co

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Benefits of concrete covers blocks in RCC work

This construction video tutorial will guide you to make concrete cover block or rebar spacer at a reasonable cost.

A rebar spacer belongs to a object that fastens the reinforcing steel or "rebar" in reinforced concrete structures since the rebar is amassed in place before the pouring of final concrete. The spacers are remained in place for the pour to set the reinforcing in place, and turn into a permanent part of the structure.

When RCC work is going on, implanting steel in concrete (called as cover) is a vital process for resisting rebar from decaying as well as arranging fire protection to the rebar. If the proposed cover is not arranged, the rebar will start to decay in due course of time and will lead to collapsing of the structure beforehand. So, cover blocks can extend the life of the structure considerably without incurring so much expenses.

The exact amount of cover is set by the application and the environment (e.g., is the RCC under water, etc.)

In India, following are considered as the standard size for the covers :

Slab : 20 mm
Beam : 25 mm
Column : 40 mm
Foundation : 50 mm

Concrete covers ensure the accurate position of steel, thus allowing in the practical application of the theoretical specifications of concrete construction. The cover of the steel concerning a specific construction component (for instance in a concrete slab or a beam) should be usually constant inside the element.

The application of covers can be beneficial to the areas where high earthquake activity along with corrosive environment (like proximity to salt water of sea) occurs.

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Published By
Rajib Dey
www.constructioncost.co

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