Experimental Study on Strength Analysis of Fibre Reinforced Bubble Deck Slabs With Conventional Labs

Written by S. BHAGAVATHIPERUMAL, R. SUBALAKSHMI, KEERTHANA B., JESSICA JENNY JAMES, A.RAJASHREE

This project introduces the Fibre Reinforced Bubble Deck Slab its uses and advantages, and its construction, which is economical and gives a lightweight structure. To use this technique, we have reduced the total construction material and concrete by 35%. This project deals with the reduction of a dead load of slab by introduction of high-density polythene bubble in the middle of the slab and fibres instead of steel reinforcements to increase the load-bearing capacity of the slab. By introducing the gap, it leads to 30 to 50% lighter slab which reduces the loads on columns, walls, and foundation, thus having various advantages over the traditional lab. 

Introduction

CEMENT

Cement must develop the appropriate strength. It must represent the appropriate theological behavior. Generally, the same types of cements have quite different theological and strength characteristics particularly when used in combination with admixtures and supplementary cementing materials. Ordinary Portland Cement of 53 grade available in local market is used in the investigation. The cement used has been tested for various properties as per 15: 4031 and found to be confirming to various specifications ofI S:12269. The specific gravity of cement was 3.15 and fineness was 3200 cm ^ 2/gm.

COARSE AGGREGATE: 

As coarse aggregates in concrete occupy 35 to 70% of the volume of the concrete. It may be proper to categorize the properties into two groups: exterior features of maximum size, particle shape, and textures) and interior quality (strength, density. porosity, hardness, elastic modulus, chemical mineral composition, etc.)Smallersizedaggregatesproducehigherconcreates strength: Particle shape and texture affect the workability of fresh concrete. The the transition zone between cement paste and course aggregates, rather than the properties of the coarse aggregates itself. Usually, an aggregate with a specific gravity of more than 2.55 and absorption of less than 1.5% (except for lightweight aggregates )can be regarded as being of good quality. Where aggregate strength is higher concrete strength is also higher. 

FINE AGGREGATE: 

Manufactured sand (M-Sand) is a substitute for river sand for concrete construction Manufactured sand is produced from hard granite stone by crushing Manufactured sand is an alternative for rivers and Due to fast growing construction industry, the demand for sand has increased tremendously, causing deficiency of suitable rivers and in most part of the world. Due to the depletion of good quality river sand for the use of construction, the theme of manufactured sand has been increased. Another reason for the use of MS is its availability and transportation cost Since manufactured sand can be crushed from hard granite rocks, it can be readily available at the nearby place, reducing the cost of transportation from far-off river sandbeds.

MAX COARSE AGGREGATE SIZE: 20MM, FINE AGGREGATE: MSAND.

PLASTIC BUBBLES: 

The bubbles are made using high density polyethylene materials. These are usually made with a non-porous material that does not react chemically with the concrete or reinforcement bars. The bubbles have enough strength and stiffness to support between 180mm to 450mm. Depending on this, the slab depth is 230mm to 600mm.The distance between bubbles must be greater than 1/9th of bubble diameter. The nominal diameter of the gaps may be 180, 225, 270, 315 or 360 mm. The bubbles may be of spherical or ellipsoidal in shape. 

ADVANTAGES OF FIBRE REINFORCED BUBBLE DECKS LABS:

1. Less weight than conventional labs 

2. Superiorstatics. 

3. Production and carrying out is easy 

4. Production Of Higher Quality 

5. To Carry It, light and cheap instruments are needed 

6. Less Concrete Is Needed 

7. Carbon Footprint Is Reduced. 

8. Earthquake & fireproof. 

9. Proper waste management(3-R principle)

APPLICATIONS OF BUBBLE DECKS LABS: 

It is used as a flooring slab in residential living, offices, utility, and industrial buildings. Used in offices, apartments, villas, hotels, schools, parking, hospitals, laboratories and factories. It is less catastrophic than conventional slabs, so they can be used in high-rise buildings in seismic zones. In addition to being used as flooring slab, it can be used in partition walls too and can also be used as a roof slab.

METHODOLOGY

1. Literature review 

2. Material testing 

3. Mixdesign 

4. Casting 

5. Curing 

6. Testingofspecimen 

7. Resultanddiscussion 

8. Conclusion

MATERIAL TESTING

The materials such as cement, fine aggregate, and coarse aggregate which are used in the concrete mix are tested. The test taken for cement is consistency and setting time of cement, for fine aggregate is a specific gravity and fineness modulus test. 

MIX DESIGN

Mix design has been calculated by using the codal provisions is10262-2019 and the result for the test is taken in the material testing such as water absorption, fineness modulus, specific gravity, setting time, consistency, etc. The grade of concrete is M30. Steel fibers are incorporated into the concrete mixture.

CASTING

After calculating the mix proportion, the concrete is prepared using the material cement, coarse aggregates, and fine aggregate along with the required water content (determined from the water-cement ratio). The mold is prepared and properly fabricated. Then the concrete is casted in the prepared mold layer by layer with compensation. Bubbles are incorporated into these labs. The Fibre Reinforced Bubble Deck slabs have been casted in moulds of dimension 1ft X 1ft. 

CURING

After the final setting time of concrete is completed, then the mold which has been cast is de-moulded. After the removal of slabs, the concrete specimen is immersed in the curing tank to attain the optimum strength. The slabs are then tested on 7,14 and 28th day of curing

TESTING OF SPECIMENS

The test conducted on the bubble deck slab is a compressive strength test. This test shall be taken for 7 days, 14 days, and 28 days curing respectively

PROPERTIES OF CEMENT

Cement is a fine powder used for bonding between components of concrete. In this project the cement would be Ordinary Portland cement (OPC) of 43 grade. Cement should be stored in proper place to avoid the formation of floc.

Fig 2. Cement

MANUFACTURED SAND

Manufactured sand (M-Sand) is a substitute of river sand for concrete construction. Manufactured sand is produced from hard granite stone by crushing. M-Sand is an alternative for river sand. Due to fast-growing construction industry, the demand for sand has increased tremendously, causing a deficiency of suitable river sand in most parts of the world. Due to the depletion of good quality river sand for the use of construction, the use of MSand has increased . Another reason for the use of MSand is its availability and transportation cost. Since manufactured sand can be crushed from hard granite rocks, it can be readily available at nearby places, reducing the cost of transportation from far-off river sand beds. 

PROPERTIES OF M-SAND 

It is used as a filler material to fill the gap i.e., the porosity of concrete is reduced. It also has high tensile strength that results from its refined structure.  

• Specific gravity -2.5 
• Water absorption -0.6%

 Fig.3.Manufactured Sand 

Steel fibers has been increasingly used in civilian and military structures, because of its superior properties compared to normal concrete, such as its higher tensile strength, better strain capacity, improved energy absorption ability, and improved toughness. Additionally, it provides exceptional control of long-term drying shrinkage cracking and load stability at the floor joints, where it is most needed. We have used crushed mechanical lathe scrap sand and incorporated this into our concrete mixture. This has been used to promote a better waste management system and the 3-R principle (Reduce-Reuse-Recycle) 

Fig 4. Lathe Scraps

RESULT OF THE EXPERIMENT COMPRESSIVE STRENGTH

Testing was done with the UTM after curing for 28 days. Dimensions of the block for testing were 0.5m × 0.5m × 0.1m. Its weight when measured was 20.43 Kg. It can be noted that the weight of the bubble deck slab is lighter in weight than the conventional slab. The maximum load on the slab was observed as 655KN. 

Compressive strength of the block = Ultimate Load/Slab Area

Table 1- Compressive Strength Values of Fibre Reinforced Bubble Deck Slabs

Graph - 1 Fibre Reinforced Bubble Deck Slabs 

Graph - 2 Fibre Reinforced Bubble Deck Slabs

Table 2 - Compressive Strength Values of Bubble Deck Slabs 

Graph - 3 Bubble Deck Slabs 

Graph - 4 Bubble Deck Slabs 

Graph-5 Compressive Strength of all 3 Slabs (Comparison)  

Graph-6 Comparison of Compressive Strength Values of all the 3 slabs