RECYCLING OF WASTE CONCRETE

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Recycling of waste concrete is done to reuse the concrete rubble as aggregates in concrete. The recycled aggregates have less crushing strength, impact resistance, specific gravity and has more absorption value as compared to fresh aggregates.

Necessity of Concrete Recycling: Millions of tonnes of waste concrete is generated every year around the world due to following reasons:

1. Demolition of old structure,
2. Destruction of buildings and structures during earthquakes and wars,
3. Removal of useless concrete from structures, buildings, road pavements etc.
4. Waste concrete generated due to concrete cube and cylinder testing, destructive methods of testing of existing structures etc.

Advantages of Concrete Recycling: Usually demolished concrete were shipped to landfills for disposal, but due to greater environmental awareness, the concrete is being recycled for reuse in concrete works. There are a variety of benefits in recycling concrete rather than dumping it or burying it in a landfill. Keeping concrete debris out of landfills saves space there. Other Benefits of Recycling of Concrete are:

• Local Product – Local Sources
• Reduces Truck Traffic
• Alternative to a Non-Renewable Resource
• Cost Savings
• No Disposal Fees
• Better Trucking Utilization (Reduced Costs)

Using recycled material as gravel reduces the need for gravel mining. There are also economic benefits. Recycled concrete is a construction material that the community does not need to pay for; those who generated the concrete waste pay a fee to have it recycled.

Fig: Process of Waste Concrete Recycling

Quality of recycled aggregate and its concrete: The strength of recycled aggregate concrete is about 10 to 15 per cent less as compared to concrete with fresh aggregate. However suitable mix designs may be made and reliable results obtained. The mix requires slightly higher quantity of cement or using admixtures to reduce water requirement. Recycled aggregate concrete can be safely used as plain concrete. With proper corrections in mix design, it can be used for R.C.C. works also.