A report on waste concrete as building material

1. Tribhuvan University
Institute of Engineering
PURWANCHAL CAMPUS
Dharan-8, Sunsari, Nepal
A
REPORT
ON
WASTE CONCRETE AS BUILDING MATERIAL
Submitted by:
Gaurab luitel (072-BAE-13)
Submitted to:
Department of Architecture
Date:
22 Aug 2020

2. Table of Contents
1. INTRODUCTION ................................................................................................................ 3
2. IMPORTANCE OF RECYCLING CONCRETE............................................................................ 3
3. WHY IS RECYCLING OF CONCRETE DONE? ......................................................................... 4
1. Economic accept........................................................................................................... 4
2. Environmental accept.................................................................................................... 4
3. Difficulties encountered in concrete recycling .................................................................. 4
4. SUSTAINABLE DEVELOPMENT PRINCIPLES, LIFE CYCLE THINKING AND RECYCLING CONCRETE
5
5. USE AS AGGREGATE ........................................................................................................ 6
1. As Coarse Aggregate ..................................................................................................... 6
2. As Fine Aggregate ......................................................................................................... 7
6. ANALYSIS OF RECYCLE CONCRETE.................................................................................... 7
I. Issue............................................................................................................................ 7
II. Remedies..................................................................................................................... 7
III. Potentials................................................................................................................. 8
7. HOW CAN RECYCLED CONCRETE BE USED? ....................................................................... 8
8. CONCRETE RECYCLING SCENARIO OF NEPAL..................................................................... 8
9. CONCRETE RECYCLING SCENARIO OF INTERNATIONAL ....................................................... 9
10. USE OF RECYCLE CONCRETE AS ARCHITECTURE FORM................................................. 10
11. CONCLUSION ............................................................................................................. 10
12. REFERENCES............................................................................................................. 10

3. 1.INTRODUCTION
Concrete is an excellent material to make long-lasting and energy efficient buildings.
Change in infrastructure planning and deteriorate with the time result in the
construction and demolition (C&D) (Devi, 2015). The emerging sustainable
development movement in the construction industry requires the recycling of the
waste building material that is degrading the environment.in many countries old
concrete is the major waste generated from the demolition of buildings /structures.
(Ruoyu Jina, 2015). . However, progress toward concrete recycling varies in different
countries for various reasons. These include the availability of technical
specifications, recycling technologies, and the level of government support. The
(C&D) is done due to various reasons like expansion of cities, natural disaster,
rearrangement of city, change in purpose, etc. for this reason, every year 850 tons of
waste is generated in the EU, which represent 31% of waste generated. (Devi, 2015).
The production of waste worldwide is 11 billion tons every year in which concrete
waste accounts for 50-70%. It was estimated that at least 3.79 million BTUs of
energy is Needed to produce each ton of cement. Accounting for 7% of CO2
emissions globally by the cement industry. (Ruoyu Jina, 2015). The reuse of concrete
is associated with the environmental benefit, to improve the recycling technology on
the concrete and it saves the cost of transporting concrete to landfill. If the concrete
is transformed into a hard state, then the concrete requires technology for
disintegration into its component. This technology development is still growing,
requiring new products and skills for disintegration. This type of technology is suitable
for those areas where aggregate is a shortage and for environmental conservation is
in priority. (Adeoye) .sand and aggregate used from the waste concrete have lower
strength than concrete made with similar aggregate not previously used. (Adeoye)
But it can be used as raw mineral materials in paving projects, footpaths, for
residential buildings, and pipe-bedding. It can be manufactured as concrete brick and
concrete blocks have a new construction material from construction and demolition
waste industry with better mechanical properties. (M. Contreras, 2016)
2. IMPORTANCE OF RECYCLING CONCRETE
Concrete is the world's most commonly used building material. Concrete waste is one of the
main waste sources of construction and demolition debris. Recycling the concrete and
reapplying has the economic value, as well as many other benefits. Firstly, the recycling as
aggregates of concrete waste reduces the volume of waste and protects natural resources. It
will reduce the rising pressure on landfill capacity as build-up and demolition of waste
concrete amounts increases. Second, recycled concrete aggregate (RCA) uses new
aggregates to reduce greenhouse gas emissions associated with concrete manufacturing.
Recycling concrete is of some significance, including:
• Removal of original capital and elimination of the associated environmental costs of
natural resource extraction
• Reduced shipping costs: Concrete will also be recycled on demolition sites or in urban
areas where it can be reused
• Reduced costs of disposal, as landfill tip charges, can be avoided.
• Good performance for some applications due to good compaction and density
properties ( e.g. as sub-base road)

4. • In some situations, recycling companies provide job opportunities that would not
otherwise exist in other sectors.
• The use of recycled concrete will save natural resources by reducing the need for
mining, gravel, water, coal, oil and gas.
3. WHY IS RECYCLING OF CONCRETE DONE?
1. Economic accept
The cost of sending waste to landfill far exceeds the expense of collecting and recycling
concrete waste from a construction site to a recycler. For a new building on the same site,
the cost of using demolition materials will also be greater than that of new materials. To
what extent materials need to be sorted and other materials removed, the recycling and
processing costs may increase. Several US states have reported savings from using recycled
aggregate up to 50 percent to 60 percent compared to new aggregates. Recycling is cheaper
than recycling in Germany, Denmark and the Netherlands. For countries without recycling
systems and the plentiful recycling of natural resources can be more expensive. Based on
situations and local conditions. Concrete recycling can be cost effective.
Factors include:
● Proximity and quantity of available natural aggregates
● Reliability of supply, quality and quantity of construction and demolition
waste(availability of materials and capacity of recycling facility)
● Public perceptions regarding the quality of recycled products
● Government procurement incentives
● Standards and regulations requiring different treatment for recycled aggregate
compared to primary material
● Taxes and levies on natural aggregates and on landfill. (development)
2. Environmental accept
Around 23% of the all the emission of greenhouse gases is due to construction.so if we
recycle the concrete we can reduce the greenhouse gases emissions. Greenhouse gas
emission can be reduced when high carbon footprint material and process of production is
reduced. Recycling concrete into aggregate will not save any amount of money compared to
the natural aggregate it saves in transportation, but it saves a huge amount of natural
resources. Research indicates that over long periods concrete, particularly crushed concrete,
can carbonate and as such reabsorb CO2. (Development)
3. Difficulties encountered in concrete recycling
Cost and energy consumption are two of the key issues in concrete recycling. A case study
conducted in Australia compared cost and benefits between
1) Dumping waste concrete in a landfill and producing natural materials for new
concrete and
2) Recycling old concrete as aggregates for new concrete. The latter approach was
found to be cost-effective while also protecting the environment and achieving
construction sustainability.
However, Gull was concerned about the labor cost incurred in the extraction of waste
aggregates from demolished Buildings and the cost of using admixture to increase the
strength of concrete containing waste aggregates. Another concern lies in the quality of

5. products made of RCA since the source of old concrete was usually unknown and the
properties of RCA were different compared to virgin aggregates . In Lauritzen, the key
concerns about concrete recycling were summarized as economy, policies and strategies,
certification of recycled materials, planning of demolition projects, and most importantly,
education and information. (Ruoyu Jina, 2015)
4. OBJECTIVE
This research aims on studying process and concrete recycled used area.
1) To understand the concrete recycling and why is it done?
2) To understand used area and process of recycling.
5. SUSTAINABLE DEVELOPMENT PRINCIPLES, LIFE CYCLE
THINKING AND RECYCLING CONCRETE
Recycling concrete is not an end in itself. An evaluation of the overall benefits of recycling
concrete for sustainable development is required. It is useful to place concrete in the
context of the environmental impact of other materials. Concrete has a high environmental
impact with respect to its input materials, namely in the cement production phase.
Transportation and delivery at all stages of production is the second greatest source of
impact. It is, however, extremely durable and can bring many environmental advantages
during the use phase.
Factors to consider when comparing recycled aggregate to virgin aggregate or other building
materials include:
● Transportation costs including fuel usage and CO2 emissions
- C&D is often already located in an urban area close to or on the construction
site, whereas virgin materials are often sourced from more distant quarries and
natural areas. Conversely, transportation costs may sometimes increase when
using recycled aggregate, as it may not always be feasible to process aggregate
on-site.
● Noise, air and water pollution and the energy needs of the processing systems
to recover the concrete or use natural materials
- Systems for different materials can be compared
- Producing coarse aggregate will have less impact than further refining;
however, future use of the aggregate has to be considered.
● Land Use Impact
- Using recycled aggregate means
- Less waste goes to landfill
- Less land is disturbed as virgin alternatives can be conserved.
● Environmental impacts during the use phase
- Recycled aggregate has similar properties to regular virgin concrete. As
such, there is usually less difference in impact from this perspective during
the use phase. Compared with other building materials, the thermal mass
of concrete means that energy savings can usually be made during the
operation of a building built with concrete as less energy is needed for
heating and cooling than for many other materials.
● Useful life expectations
- The durability of concrete and recycled concrete means that its long useful
life can be a sustainability benefit compared with other materials.

6. 6. USE AS AGGREGATE
Most recycled concrete is used as aggregate in road sub base, and most commonly in
unbound form. The quality of aggregate produced depends on the quality of the original
material and the degree of processing and sorting. Contamination with other materials also
affects quality. More refined aggregate may produce a product of higher value use but may
also have a greater environmental impact in production. When well cleaned, the quality of
recycled coarse aggregate is generally comparable to new aggregate and the possibilities for
use are equally comparable, although some limitations as to strength may exist. Material
containing plasterboard can have more limited applications. Recycled aggregate accounts for
6% to 8% of aggregate use in Europe, with significant differences between countries. The
greatest users are the United Kingdom, the Netherlands, Belgium, Switzerland and Germany.
It was estimated in 2000 that ~5% of aggregate in the US was recycled aggregate.
1. As Coarse Aggregate
For road base, sub-base and civil engineering applications
It is widespread and most widely used for road foundation, pavement and sub-base
use. The Federal Highway Administration, which adopted a pro-use policy and
conducted research in the field, has encouraged its use and acceptance in the US.
Finnish research has found that recycled concrete listed in the quality and
composition accepted in the sub-base and base layers can reduce the thickness of
these layers due to the good material bearing properties. When used as a base and
sub-base, the unbound cementation material in recycled aggregates was found to
have a bonding that is superior to that of fines in new aggregates, so that the
strength is strengthened to provide a very strong foundation for new pavements. It
can also be used in asphalt mixtures. Various civil engineering projects can also make
use of coarse aggregate.
For concrete
A common misperception is that recycled concrete aggregate should not be used in
structural concrete.
Guidelines and regulations sometimes consider the physical limitations of recycled
concrete aggregate, but ideally they should also promote its use. A study by the
National Ready Mixed Concrete Association (NRMCA) in the US has Concluded that
up to 10% recycled concrete aggregate is suitable as a replacement for new
aggregate for most Concrete applications, including structural concrete.UK research
indicates that up to 20% of recycled concrete aggregate can be used for most
applications (including structural) . Australian guidelines note that up to 30%
Recycled aggregate content in structural concrete can be as high as 30% without any
significant difference in workability and strength as opposed to natural aggregates.
German guidelines note that recycled aggregate can be used for up to 45 per cent of
the total aggregate in some conditions, depending on the concrete exposure level.
As recycled concrete aggregate has cement in it, when reused in concrete it tends to
have higher water absorption and can have lower strength than new aggregate.
Sometimes more cement is needed.

7. 2. As Fine Aggregate
Fine aggregates can be used in place of natural sand. However, the mortar content can
affect workability, strength and shrinkage due to high water absorption, which could
increase the risk of settlement and dry shrinkage cracking. Fine aggregates also often
contain plaster from C&DW and it is more costly, both economically and environmentally, to
clean the material. Fine aggregates can be a good fill for sub-grade corrections as they can
act as a drying agent when mixed with sub-grade soil. Fine aggregates can be used in sub-
base and in all-in aggregate uses. Given the impact of extraction of sand from rivers and
seas, alternative sources are of increasing importance and use may increase as a result of
this.
Reuse in original form
Reuse of blocks in original form, or by cutting into smaller blocks, has even less
environmental impact; however, only a limited market currently exists. Improved building
designs that allow for slab reuse and building transformation without demolition could
increase this use. Hollow core concrete slabs are easy to dismantle and the span is normally
constant, making them good for reuse. Some examples of varied uses include:
● Recycled concrete from construction and road rubble has been found to be a good
material for artificial reefs. The irregular surfaces and pore spaces of crushed
concrete provide good protection to small oysters from predators
● Thailand uses concrete waste to make paving blocks, pots and benches for
community use.
7. ANALYSIS OF RECYCLE CONCRETE
I. Issue
● Availability of material
● Processing infrastructure
● Public attitudes
● Laws, regulations and industry accepted standards
● Environmental impacts
● Physical properties
● Leaching
The quality of recovered aggregate is largely dependent on the quality of the original
concrete and any exceptional conditions the concrete may have endured in its first
life. In a Dutch study, some leaching of bromine and chromium was found in some
recycled concrete. In Japan, it has been noted that hexavalent-chromium and lead
can be found in concrete waste as they are originally contained in cement.
(Development)
II. Remedies
● Available of the material from the cities, old buildings in all countries that can be
used as the raw material for the next building.
● C&D on-site waste management plans are needed. This plan requires a huge amount
of economy that can be done by the C&DW, this will lead to fast economic and
environmentally friendly demolition.

8. ● The misconception that recovered concrete is of lower quality. New materials are
perceived as being of better quality. Properly demolished and separated in the
original raw material can have a good amount of strength, compression sometimes
higher.
● Processing technology for recovery of concrete should consider possible air and
noise pollution impacts as well as energy consumption, although there is little
difference to natural aggregates processing because it is done in the mines if we
place the buffer and insulation that can be reduced. (Development)
III. Potentials
● Aggregate levies and the costs of transportation for natural aggregates could be
higher. Overall project costs will be minimized as C&DW charges fewer landfill taxes
/ fees because the waste is recycled instead of landfilled.
● C&D appears to be located in large cities close to building and growth projects.
Sometimes, virgin materials need to be transported over wider distances.
● Once infrastructure has been built, mobile sorting units can provide good returns
and dedicated facilities can.
● Growing environmental issues resulting in greater demand for environmentally
friendly goods and material reuse.
● Positive recycling laws, landfill taxes and green procurement policies by large users
can all promote recycled concrete use. (Development)
8. HOW CAN RECYCLED CONCRETE BE USED?
● As aggregate (coarse and fine)
● As blocks in original or cut-down form
● “Recycled aggregate” is used in this report to mean aggregate made from old
concrete.
9. CONCRETE RECYCLING SCENARIO OF NEPAL
Figure 1 Manohara River Bank, Near Sankhmul used as dumping for concrete

9. Cities like Kathmandu valley are growing day by day, new construction and
demolition are taking place in different parts of the valley.
Old construction is done by using brick and surkhi . Due to the modernization in
place of old material, concrete is used for low maintenance, its versatility, resistance,
ease of handling, accessibility, aesthetics, and other factors. With the time pass this
material will destroy property.so to make it sustainable without degrading the
environment and reusing again and again concrete there should be a concrete
recycling plant. That can be accessible by all in Kathmandu valley. Then the problem
of concrete will not be.
Figure 1 concrete recycling process
In figure 1, concrete is thrown in the back of the river that is degrading water life, the
aesthetic of the city, creating a dumping area in the river bank. Instead, concrete can
be sent to a recycling plant shown in figure 2 that can be used as the road sub base
or can be ground and split into cement raw material (clinker) and recycling aggregate
that can be used as again as the concrete for building.
10. CONCRETE RECYCLING SCENARIO OF INTERNATIONAL
Significant potential remains for increasing the use of coarse recycled aggregate in
concrete. In some countries, notably Germany, Switzerland and Australia, concrete
containing recycled aggregate is now being marketed. For example, Boral “green”
concrete is premixed concrete using recycled aggregate that has been used in a
number of building projects in Australia, including the world leading green building
Council House 2, a 10-storey office block in Melbourne.
A notable example from Germany is the Waldspirale complex containing 105
residential dwellings designed by Friedensreich Hundertwasser in Darmstadt.

10. Completed in 2000, the building makes use of recycled aggregate in the concrete.
Zürich’s largest school in Birch has led the way for the use of recycled aggregate in
concrete in Switzerland. In Spain, Horcimex used recycled aggregate content in the
structural concrete for a housing project in Madrid. To the extent that recycled
aggregate is used in concrete,
It tends to be mainly in ready-mix concrete. Some examples from France exist for use in pre-
cast concrete; however, the CSI is not currently aware of any widespread use
11. USE OF RECYCLE CONCRETE AS ARCHITECTURE FORM
● The most common down cycling use is of shredded or pebbled concrete as
aggregate, or filler in roadbed construction, retaining walls, and earthworks.
(blander, 2019)
● Base for new asphalt clearing: Through a cycle called rubblization, old solid asphalt
can be broken set up and utilized as a base layer for black-top asphalt laid over it.
● Bed establishment material for channels containing underground utility lines: Utility
channels are stove secured with rock to help waste, and squashed solid makes a
decent, reasonable substitute for rock.
● Aggregate for blending new concrete: Crushed cement can replace a portion of the
new total utilized in prepared blend concrete.
● Controlling stream bank disintegration: Larger parts of squashed cement put along
weak stream banks can help control disintegration.
● Landscaping mulch: When appropriately squashed and very much arranged, ground
cement can supplant waterway rock or different rock utilized as ground covers and
mulch.
● Fill for wire gabions: Wire confines (gabions) loaded up with squashed rock can
make enhancing and useful security screen dividers or holding dividers. (Rodriguez,
n.d.)
12. CONCLUSION
This study points out concrete can be reused and restored. The ultimate target for "zero
landfill" concrete should be set. It should be noted, however, that cement producers can
only play an indirect role in promoting concrete recycling (concrete is the main downstream
cement product) and a target of "zero landfill" concrete. The goals of this study include
encouraging dialogue and developing awareness about concrete recycling. Cement
producers in the concrete, aggregate and building industries may be especially concerned
with the work of the subsidiaries. Cement producers may also promote recycling efforts by
way of this article. (Development)
13. REFERENCES
Adeoye, A. a. (n.d.). Recycling Of Concrete Waste Material from Construction Demolition.
Akure: American Journal of Engineering Research (AJER).
blander, a. (2019). Retrieved from metropolis:
https://www.metropolismag.com/architecture/recycling-demolition-building-materials/
development, w. b. (n.d.). recycling concrete.

11. Devi, Y. G. (2015). An Innovative Study on Reuse of Demolished Concrete Waste. Thiruvalla,
Kerala, India: Journal of Civil & Environmental.
M. Contreras, S. T. (2016). Recycling of construction and demolition waste for producing
new. brazil: Elsevier Ltd.
Rodriguez, J. (n.d.). Ways to Recycle and Reuse Concrete. Retrieved from the balance small
business: https://www.thebalancesmb.com/recycling-concrete-how-and-where-to-reuse-
old-concrete-844944
Ruoyu Jina, Q. C. (2015). Investigation of concrete recycling in the U.S. construction industry.