“Green concrete or Eco Concrete is the same as normal concrete, but it’s made from waste material or eco-friendly material”
Sometimes, we relate this concrete with his name green concrete, but there is no relation between its colors. Green concrete has the same color that has by normal concrete. Green concrete may be made by adding eco-friendly materials, so it also is known as environmentally friendly concrete.
Green concrete is very cheap to produce because for making we use waste products such as a partial substitute for cement and aggregates. The use of concrete in the construction industry is growing at a faster rate and with the development of urban society and its need boosts demand for construction materials. The Cement and aggregates are the main constituents of concrete and the continuous mining reduced the source of availability. This scenario created the problem of a shortage of construction materials in recent times. To fulfill the shortage, there is a need to find a replacement to some extent.
Nowadays, the construction industry is looking for alternative material and the solution is known as “Green Concrete”. Green concrete is a new type of concrete in the field of the sustainable construction industry. It is a revolutionary concept of making concrete in the construction industry. Green concrete was first developed by Dr. WG. in Denmark in the year 1998.
Why Use Green Concrete:
Nowadays, the word “Green” does not only represent the green color but is also a symbol of saving the environment which is surrounding us.
- To Reduce Co2 Emission:
In conventional concrete, we use a material whose production process involves the emission of a large amount of co2 in the environment. Whereas green concrete uses waste eco-friendly material which emits too low co2 in the environment.
- To Decrease the Demand for Conventional Material:
As discussed above the construction industry growth is too fast in recent year and consumption of concrete is also increased to a large extent. Because of this and limited source of mining leading to a shortage of conventional construction material like cement, aggregate. Therefore to reduce the demand for regular construction material the green concrete is a better alternative.
- To Recycle and Reuse the Materials:
As construction of any structure involve a huge amount of materials and also it produces a large amount of construction waste. This waste never utilized for any other work. So, the green concrete has the idea to recycle and reuse this waste material for making concrete.
Green Concrete Materials:
Green concrete materials are the Waste materials such as blast furnace slag, fly ash, silica fume, recycled glass, and wood ash are used as an alternative for cement in the production of green concrete. Recycled concrete materials, waste plastic, demolition waste, recycled glass aggregate, foundry sand, and stone crusher waste have used an alternative for aggregate in the production of green concrete.
Alternative Material of Cement:
- Ground Granulated Blast Furnace Slag:
The Ground Granulated Blast furnace slag is the waste material in the production of steel and iron in the factory. The 0-80% replacement of GGBS in different grades of concrete gives more compressive strength and flexural strength The GGBS addition in concrete about 40% of replacement gives 9% more strength in 7 days and increasing of 6% strength with 30% replacement attains in 28 days.
- Fly Ash:
Fly ash is the finely divided residue that results from the combustion of pulverized coal and it waste material of coal-based electrical power generation plant. Concrete with high compressible strength and fracture toughness is possible by replacing cement with fly ash by weight as the results shown by Grzegorz Ludwik Godlewski (2018) from the tests on three groups of fly ash content 0%, 20%, and 30%.
- Silica Fume:
Silica fume is one of by-product in the manufacturing process of silicon and ferrosilicon and consists of spherical particles with an average particle diameter of 150 nm.
A mix of silica fume and marble waste powder was used as a replacement for cement and sixteen concrete cubes were tested by Ali Kodabakhshian (2018) to examine durability. The results indicated that the mix improved strength and durability. Cement excessive use reduces and decreases harmful environment effect and it resulted in a 30% cement consumption reduction.
- Recycled Glass:
Concrete blocks, self-compacting concrete, and architectural mortar were produced by using recycle waste glass as per overview by Tung-Chai Ling (2013) on current management and recycling of waste glass in Hong Kong.
- Date Palm Ash:
Concrete specimens with date palm ash-based mortar with 10%, 20% and 30% replacement of cement were tested by Walid Al- Kutti (2019). This study result indicates that there is an overall improvement in the quality of concrete by a 10% dosage of palm ash.
Alternative Materials of Aggregate:
- Foundry Sand:
It is quality silica sand, clean, uniformly sized used in foundry casting processes. The sand is used to make molds or patterns used for ferrous (iron and steel) and non-ferrous (copper, aluminum, brass) metal castings.
Treated foundry sand was used as an alternative for fine aggregate with the various percentages by weight and tests were conducted by Gurumorthy (2019) for water absorption, sorptivity, and rapid chloride permeability. Concrete made with 30% additive foundry sand showed better durability.
- Waste Plastic:
Marshall stability analysis was performed by Shubham Bansal (2017) on samples with partially replacing optimum bitumen content by waste plastic with 4%, 6%, 8% and 10% and crumb rubber with 5%, 10%, and 15%. Waste plastic resulted in a 16% increment in strength while rubber material resulted in a 50% increment in strength.
- Demolition Waste:
Precast concrete building blocks made with recycled demolition waste aggregate were tested by Marios Soutsos (2011). The laboratory test results showed that there was no reduction in strength.
- Farming Waste:
Farming waste from bamboo, corn, wheat, olive, sisal, and seashell can be used to produce concrete with improved performance. However, these waste have to be given appropriate treatment methods as indicated by Kim Hung Mo (2016).
Application of Green Concrete:
- It is used in the construction of bridges
- It is widely used in the building Construction
- It is used in the construction of Column
- It can be used in the Road Construction
- Environmental Benefits of Green Concrete:
- Durable Concrete and Long Life:
This concrete is cable to gain strength quicker compared to normal concrete and has a lower rate of shrinkage than concrete made only from Portland cement. Structures built from green concrete have better fire resistance, as it can withstand temperatures of up to 2400°F. Green concrete also has better corrosion resistance which is important with the effect pollution has had on the environment. Acid rain greatly reduces the durability of traditional building materials.
All of those factors contributing to increasing the durability of green than one made with ordinary concrete. Similar concrete ingredients and mixtures have been found in ancient Roman structures. This material was also found to be used in Ukraine in the 1950s and 1960s. it has been over 50 years later, those Ukrainian buildings are still standing.
- Reduces Energy Consumption:
When you use fly ash as a replacement of cement and it means you are saving energy. It is because cement production involves a large amount of energy. The raw materials that are used in the manufacturing of Portland cement require huge amounts of coal or natural gas to heat. Fly ash is already one of a byproduct of another industrial process, so you are not expending much more energy to use it to create green concrete. Another advantage of green concrete is that reduces the energy consumption in a building as it is more resistant to temperature changes, thus saving heating and cooling costs.
- Reduces Carbon Dioxide Emissions:
The main component of ordinary cement is pulverized limestone, clay, and sand which are heated to a high temperature. This process is emitting around 5 and 8% of all Carbon Dioxide emissions worldwide. The manufacturing of green concrete can lead to a reduction of carbon emission by up to 80%. As a part of saving the global environment, switching completely to green concrete for construction will help considerably.
Green Concrete Advantages and Disadvantages:
Green Concrete Advantages:
- There is no need to change the manufacturing process of concrete for green concrete.
- It is made from waste and recycled materials like fly ash, GGBS (Ground Granulated Blast Furnace Slag, artificial aggregates, etc. in the concrete.
- It decreases CO2 emission and helps in reducing the environmental pollution.
- It has good thermal and acid resistance.
- It solves the problem of recycling and disposal space required for industry waste material as it is made from residue waste material.
- It is most suitable for mass concrete work as it produces less heat of hydration.
- Green concrete compressive and split tensile strength is better with some materials compared to conventional concrete.
- It contributes to reducing the consumption of cement overall.
- It is economical compared to conventional concrete.
- It offers better workability than conventional concrete.
Green Concrete Disadvantages:
- Structures made with some types of green concrete have comparatively less Life than structures with conventional concrete.
- Compressive strength may vary with the change of green materials.
- Water absorption is high.
- Its Shrinkage and creep properties are high compared to conventional concrete.
- Flexural strength is less in green concrete
Expert Verdict or Opinion:
There is significant scope in the use of waste materials to produce green concrete.
Replacing regular concrete material with the waste materials and by-products gives an opportunity to manufacture economical and environment-friendly concrete.
Partial replacement of concrete materials like cement and aggregate with waste material and admixtures shows better compressive and tensile strength, improved sulphate resistance, decreased permeability and improved workability.
But, the Construction industry required faster construction and quick availability of materials. Making green concrete material availability is a big problem.
Source: Bhushan Mahajan (civiconcepts)
