Development of Eco-Friendly Bricks with Industrial By-Product

. Use of fly-ash bricks than conventional clay bricks is an environmentally friendly alternative. Fly-ash bricks are cost-effective, strength, crack resistance, low maintenance, durable and eco-friendly. In this project to increase the strength of the fly-ash bricks, nylon fibres are used. Nylon fibres are synthetic fibres which is recycled from nylon waste. Similar to plastics, nylon waste is also produced in large amount which causes environmental pollution. So, to reduce this impact of nylon fibres are used in fly-ash bricks to increase its mechanical properties. The major goal is to improve the fly-ash brick mechanical properties of the fly-ash by conducting Compression Strength test, Water Absorption test and Efflorescence test. Hence result has been studied of fly-ash bricks reinforced with nylon fibres has shown promising results in all areas, suggesting that it could be used in load bearing walls, foot paths, pavements.


Introduction
Bricks are the most commonly used building material.Now a days different types of bricks such as concrete blocks, fly-ash bricks, burnt clay bricks, engineering bricks and sand lime bricks are been used in constructions.Among these bricks, fly-ash bricks are widely used because of its cost, high strength and durability.Fly-ash bricks (Fig. 1) are made from industrial waste material such as fly-ash, which is a by-product of coal-fired power plants.Hence these bricks represent sustainability at the highest level.The manufacturing process of fly-ash bricks involves mixing of fly-ash, cement, sand and water in a predetermined ratio.The goal of this research to increase the strength and durability of the bricks by incorporating waste synthetic fibres.Nylon fibres reduces micro cracking and also increases compressive and tensile strength.Improper disposal of waste nylon causes pollution and also contaminates soil which also affects the ground water table.So recycled nylons are made into fibres and incorporated in fly-ash bricks which can be used in construction.Hence these bricks facilitate environmentally friendly approach and sustainability.

Materials Used 2.1 Cement
Cement (Fig. 2) is one of the most important binding agents used for building materials.Generally, it is made up of limestone, clay or sand, bauxite and iron ore.Cement mixed with water causes a chemical reaction and forms a paste that sets and hardens to bind the structure of building materials.

Fly-ash
Fly-ash (Fig. 3) is most commonly used as a pozzolan in plain cement concrete.Fly-ash is the finely divided residue that results from the combustion of pulverized coal.These are used in the area of Portland cement concrete, soil road base stabilization, grouts, structural fill etc.They are classified as Class C or Class F based on its chemical composition.

Manufactured Sand
Manufactured sand or M-Sand (Fig. 4) is artificial sand produced from crushing hard stones into small sand sized angular shaped particles, washed and finely graded to be used as construction aggregate.It is an alternative to River Sand for construction purpose.

Nylon Fibres
Nylon fibres (Fig. 5) are formed from recycled nylon waste and acts as reinforcing agents that improve the bonding capacity of the cement matrix in bricks, making them to more resistant to external forces such as wind, earthquakes and heavy loads.Hence these synthetic fibres provide cost-effective and practical solution for the construction industry, as it improves quality, longevity and the strength of the bricks.

Methodology
The following is a methodology (Fig. 6) for producing fly ash bricks reinforced with nylon fibres: Fig. 6.Methodology of producing fly-ash bricks reinforced with nylon fibres

Collection of Materials
The raw materials for manufacturing fly-ash bricks such as cement, sand, fly-ash, water and nylon fibres are collected.These are mixed in the desired mix proportion.Water is added to form a uniform mixture.

Mixing of Materials
The fly-ash and sand are mixed together first, then cement is added to the mix.Water is added in the pan mixer to obtain uniform slurry.The mixed slurry is added with nylon fibres in the appropriate percentage and mixed thoroughly to ensure even distribution of the fibres.

Moulding
The mixed slurry is poured into the brick mould which is generally made of metal or plastic.Then the moulds are vibrated to ensure the uniformity settlement of the slurry.

Curing
The moulded bricks are then kept in a chamber for a period of 24 to 48 hours.During this time, the bricks undergo a chemical reaction and gains strength.

Drying & Finishing
After the curing process, the bricks are removed from the moulds and kept under the sun for a period of 7 to 10 days.After the bricks have dried, they are polished to give a smooth finish.The bricks are then ready to be used in constructions.

Mix Proportion
The mix proportion of fly-ash brick is in the proportion of 40%,20%,40% and the water content is found by trial and error.The fibres are added in the ratio of 1.5%,2%,2.5%.The size of the brick is 230x110x80mm.The mix proportion table 1

Compression Test
Fig. 7 shows the graph which demonstrates the compression strength of different percentage of nylon fibres used in fly-ash bricks.

Fig. 7. Compression Strength graph
Compression strength increases, as the percentage of fibre increases.The highest strength is given by the 2.5% of fibre added to the fly-ash brick.

Water Absorption
Fig. 8 shows the graph which demonstrates the water absorption of different percentage of nylon fibres used in the fly-ash bricks.

Efflorescence Test
There is no white precipitate formed therefore, the degree of efflorescence is zero.

Conclusion
The purpose of the project is to increase the strength of the fly-ash brick by reinforcing nylon fibres.The results indicate that addition of nylon fibres have increased the compression strength which in turn increases micro cracking resistance.The highest compression strength is given by the fly-ash brick reinforced with nylon fibres of 2.5%.Increase of fibre, increases compression strength in contrast water absorption also increases.This increase in water absorption may affect the durability of the bricks.So, to avoid these hydrophobic materials can be used which stabilizes to prevent water attack to obtain a durable and efficient fly-ash brick.

Table 1 .
is given below Mix proportion table Water Absorption graphWater absorption increases, as the percentage of fibres increases.The highest water absorption is given by the fly-ash brick reinforced with nylon fibres of 2.5%.