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AN INVESTIGATION ON PROCESSING AND PROPERTIES OF RECYCLED AGGREGATE CONCRETE Das A. 1* , Alauddin M. 2 & Hossain B.M. 2 1 Asst. Professor, Department of Civil Engineering, Southern University Bangladesh (SUB), Chittagong, <[email protected]> 2 Student, Department of Civil Engineering, Southern University Bangladesh (SUB), Chittagong, <[email protected]> 3 Student, Department of Civil Engineering, Southern University Bangladesh (SUB), Chittagong, <[email protected]> ABSTRACT A significant amount of natural resource can be saved if the demolished concrete is recycled for new construction. In addition to the saving of natural resources, recycling of demolished concrete will also provide other benefits, such as the creation of additional business opportunities, saving the cost of disposal, saving money for local government and other purchasers’ etc. Recycled aggregate is comprised of crushed, graded inorganic particles processed from the materials that have been used in the constructions and demolition debris. The objective of this thesis is to achieve the target strength of concrete by using recycled aggregate fully or partially with the natural fresh stone. Local sand (FM value 1.83) is used as fine aggregate. In this investigation, demolished concrete blocks are collected from demolished head of the Pile and broken into pieces as aggregates as per ASTM C33. In this study, ACI 211-91 is used for mix design & conducted compressive strength test for 72 cubes (100mm x 100mm x 100mm) with different mix ratios. The test Result has revealed that maximum 65%-84% of target strength can be achieved from recycled aggregate. Keywords: Recycle Aggregate; Fresh Aggregate; Concrete Compressive Strength; Slump test; INTRODUCTION The generation of huge amounts of construction waste is anticipated due to the demolition of older structures such as power stations built more than 30 years ago. On the other hand, the reuse of construction waste is highly essential from the viewpoint of Life Cycle Assessment (LCA) and effective recycling of construction resources. In order to promote the reuse of construction waste, it is necessary to achieve three basic concepts: (1) assurance of safety and quality, (2) decrease of environmental impact, and (3) increase of cost effectiveness of construction. This paper outlines the development of a recycling system, application of recycled aggregate concrete produced by the aggregate replacing method, which is effective in reducing both cost and environmental impact from the viewpoint of LCA for concrete waste generated by the demolition of large-scale buildings such as powerhouses. Global Construction industry growth is substantial in size. In a report of global insight, it is predicted that construction expenditure has been increased about 1400 billion US dollar from the year 2008 to 2013. These figures indicate a tremendous growth in the construction sector almost one and a half times in the coming 5 years. The construction industry Worldwide is a conspicuous consumer of the raw material of many types and thus large material inventories are required to sustain the growth. Also proportionately related are the issues of cost that is rising since material inventory is becoming scarce and material has to be procured from distant places. Among the various raw materials used in construction, aggregates are important components for all the construction activities and the demand in 2007 has seen an increase by five percent, to over 21 billion tones, the largest being in developing 1st International Conference on Research and Innovation in Civil Engineering (ICRICE 2018), 12 –13 January, 2018, Southern University Bangladesh (SUB), Chittagong, Bangladesh ISBN: 978-984-34-3576-7

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Page 1: AN INVESTIGATION ON PROCESSING AND PROPERTIES OF …€¦ · tested for absorption capacity, specific gravity, moisture content, unit weight, and FM. The specific gravity and absorption

AN INVESTIGATION ON PROCESSING AND PROPERTIES OF

RECYCLED AGGREGATE CONCRETE

Das A.1*, Alauddin M.2 & Hossain B.M.2

1 Asst. Professor, Department of Civil Engineering, Southern University Bangladesh (SUB),

Chittagong, <[email protected]> 2 Student, Department of Civil Engineering, Southern University Bangladesh (SUB), Chittagong,

<[email protected]> 3 Student, Department of Civil Engineering, Southern University Bangladesh (SUB), Chittagong,

<[email protected]>

ABSTRACT

A significant amount of natural resource can be saved if the demolished concrete is recycled for new

construction. In addition to the saving of natural resources, recycling of demolished concrete will also

provide other benefits, such as the creation of additional business opportunities, saving the cost of

disposal, saving money for local government and other purchasers’ etc. Recycled aggregate is

comprised of crushed, graded inorganic particles processed from the materials that have been used in

the constructions and demolition debris. The objective of this thesis is to achieve the target strength of

concrete by using recycled aggregate fully or partially with the natural fresh stone. Local sand (FM

value 1.83) is used as fine aggregate. In this investigation, demolished concrete blocks are collected

from demolished head of the Pile and broken into pieces as aggregates as per ASTM C33. In this study,

ACI 211-91 is used for mix design & conducted compressive strength test for 72 cubes (100mm x

100mm x 100mm) with different mix ratios.

The test Result has revealed that maximum 65%-84% of target strength can be achieved from recycled

aggregate.

Keywords: Recycle Aggregate; Fresh Aggregate; Concrete Compressive Strength; Slump test;

INTRODUCTION

The generation of huge amounts of construction waste is anticipated due to the demolition of older

structures such as power stations built more than 30 years ago. On the other hand, the reuse of

construction waste is highly essential from the viewpoint of Life Cycle Assessment (LCA) and

effective recycling of construction resources. In order to promote the reuse of construction waste, it is

necessary to achieve three basic concepts: (1) assurance of safety and quality, (2) decrease of

environmental impact, and (3) increase of cost effectiveness of construction. This paper outlines the

development of a recycling system, application of recycled aggregate concrete produced by the

aggregate replacing method, which is effective in reducing both cost and environmental impact from

the viewpoint of LCA for concrete waste generated by the demolition of large-scale buildings such as

powerhouses.

Global Construction industry growth is substantial in size. In a report of global insight, it is predicted

that construction expenditure has been increased about 1400 billion US dollar from the year 2008 to

2013. These figures indicate a tremendous growth in the construction sector almost one and a half times

in the coming 5 years. The construction industry Worldwide is a conspicuous consumer of the raw

material of many types and thus large material inventories are required to sustain the growth. Also

proportionately related are the issues of cost that is rising since material inventory is becoming scarce

and material has to be procured from distant places. Among the various raw materials used in

construction, aggregates are important components for all the construction activities and the demand in

2007 has seen an increase by five percent, to over 21 billion tones, the largest being in developing

1st International Conference on Research and Innovation in Civil Engineering (ICRICE 2018), 12 –13 January, 2018, Southern University Bangladesh (SUB), Chittagong, Bangladesh ISBN: 978-984-34-3576-7

Page 2: AN INVESTIGATION ON PROCESSING AND PROPERTIES OF …€¦ · tested for absorption capacity, specific gravity, moisture content, unit weight, and FM. The specific gravity and absorption

countries like China, India, etc. Keun- Hyeok Yang has reported construction industry’s global

requirement of natural aggregate Around 8 - 10 billion tons annually after the year 2010. (1 p. 6)

METHODOLOGY (SECTIONS)

When recycled aggregate concrete is applied to buildings, road base etc., the quality required is generally equivalent to natural aggregates such as gravel and sand.

Experimental Methods

The overall experimental program consisted of two stages: 1) a comprehensive study of the properties

of new concrete made with recycled aggregate that is prepared by crushing partially hydrated old concrete; 2) a study of the effect of recycled fines only on the properties of new concrete. This paper presents the results of stage 1 of the study. Demolished concrete blocks are collected from the structural members of the demolished buildings. The collected concrete samples were have been broken into pieces mechanically in particular sizes as 5 mm to 20 mm FM of which is 4.20. The aggregates are tested for absorption capacity, specific gravity, moisture content, unit weight, and FM. The specific gravity and absorption capacity are determined as per ASTM C128, (2 p. 6) unit weight as per ASTM C29. The FM, water absorption and specific gravity of sand used in this investigation were 1.83, 3.95%, and 2.55, respectively. After investigation of aggregates, concrete cube specimen of size 100 mm x 100 mm x 100 mm in are made for evaluation of compressive strength at 7, 21, 28 and 60 days as per ASTM

C39. W/C ratios of recycled aggregate concrete are 0.65, 0.61 and 0.52. In addition, W/C ratios of fresh aggregate concrete were 0.48, 0.45 and 0.39. Cement content of concrete 185 kg/m3 as per (3 p. 6) for all cases. Then the specimens are cured under water continuously. The compressive strength of concrete was measured at 7, 21, 28 and 60 days by using Universal Testing Machine (UTM). The failure surfaces of concrete were also checked carefully after crushing of the concrete cube. About 72 concrete cubes were investigated for 6 cases as summarized.

Research Program

Materials collection

Fresh aggregate Demolished aggregate

Fine aggregate Cement

Test of the materials properties

Mix design

Mix ratio

Casting and curing of cubes

Compressive strength test

Compare and evaluation

Conclusion

1st International Conference on Research and Innovation in Civil Engineering (ICRICE 2018), 12 –13 January, 2018, Southern University Bangladesh (SUB), Chittagong, Bangladesh ISBN: 978-984-34-3576-7

Page 3: AN INVESTIGATION ON PROCESSING AND PROPERTIES OF …€¦ · tested for absorption capacity, specific gravity, moisture content, unit weight, and FM. The specific gravity and absorption

RESULTS AND DISCUSSIONS

General

Benefits of recycled aggregate (RA) in concrete can be described in environmental protection and

economical terms. The application of recycled aggregate in construction activities has been practiced

by developed countries and also of some Asian countries. This paper reports the results of an

experimental study on the mechanical properties of recycled aggregate concrete (RAC) as compared to

natural aggregate concrete (NAC). The 100% of RA used in the concrete mix to replace the natural

coarse aggregate in concrete number 100 x 100 x 100 cube mm were cast with target compressive

strength is 21, 28 and 32 MPa within 7, 21, 28 and 60 days curing period.

Table: Finesse Modulus of fine & coarse aggregate. (4 p. 6)

Fine Aggregate F.M

Local Sand 1.33

Sylhet Sand 2.34

Combined (Local &

Sylhet)

1.83

Coarse Aggregate F.M

Recycled 4.20

Fresh 5.70

Table: Unit weight, specific gravity, absorption capacity, moisture content of fine aggregate. (4

p. 6)

Fine

Aggregate

Unit Weight

(kg/m3)

Specific

Gravity

Absorption

Capacity, %

Moisture Content,

%

Local Sand 1606 2.55 3.95 2.70

Sylhet Sand 1500 2.54 3.09 2.06

Table: Unit weight, specific gravity, absorption capacity, moisture content of course

aggregate. (4 p. 6)

Coarse

Aggregate

Unit Weight

(kg/m3)

Specific

gravity

Absorption

capacity, %

Moisture content,

%

Recycled 1235 2.14 8.64 1.70

Fresh 1628 2.73 0.70 2.06

1st International Conference on Research and Innovation in Civil Engineering (ICRICE 2018), 12 –13 January, 2018, Southern University Bangladesh (SUB), Chittagong, Bangladesh ISBN: 978-984-34-3576-7

Page 4: AN INVESTIGATION ON PROCESSING AND PROPERTIES OF …€¦ · tested for absorption capacity, specific gravity, moisture content, unit weight, and FM. The specific gravity and absorption

Graphical Representation

Fig. Comparison of concrete compressive strength Recycle Aggregate Concrete (RAC) vs. Fresh

Aggregate Concrete (FAC) between Curing Periods M 21

Fig. Comparison of concrete compressive strength Recycle Aggregate Concrete (RAC) vs. Fresh

Aggregate Concrete (FAC) between Curing Periods M 28

Fig. Comparison of concrete compressive strength Recycle Aggregate Concrete (RAC) vs. Fresh

Aggregate Concrete (FAC) between Curing Periods M 32

7.5

15.6 16.3 17.611.9

20.7 20.922.6

0.0

5.0

10.0

15.0

20.0

25.0

7 21 28 60

Co

mp

ress

ive

Str

eng

th (

MP

a)

Curing Period (days)

Compressive Strength RAC vs FAC-21 MPa

Recycled Concrete

Fresh Concrete

11.2

17.8 18.0 19.616.0

23.0

27.7 28.2

0.0

5.0

10.0

15.0

20.0

25.0

30.0

7 21 28 60

Co

mp

ress

ive

Str

eng

th

(MP

a)

Curing Period (days)

Compressive Strength RAC vs FAC-28 MPa

Recycled Concrete

Fresh Concrete

13.5

21.1 22.4 22.918.1

31.6 31.9 32.1

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

7 21 28 60

Co

mp

ress

ive

Str

eng

th (

MP

a)

Curing Period (days)

Compressive Strength RAC vs FAC-32 MPa

Recycled Concrete

Fresh Concrete

1st International Conference on Research and Innovation in Civil Engineering (ICRICE 2018), 12 –13 January, 2018, Southern University Bangladesh (SUB), Chittagong, Bangladesh ISBN: 978-984-34-3576-7

Page 5: AN INVESTIGATION ON PROCESSING AND PROPERTIES OF …€¦ · tested for absorption capacity, specific gravity, moisture content, unit weight, and FM. The specific gravity and absorption

Fig. Comparison of concrete compressive strength Recycle Aggregate Concrete (RAC) between

Curing Periods M21, M28, M 32

Fig. Comparison of concrete compressive strength Fresh Aggregate Concrete (FAC) between

Curing Periods M21, M28, M 32.

DISCUSSION

Concrete specimen made with the aggregate got from demolished concrete has achieved

65-84% of the strength for which it has been supposed to be designed. On the other hand,

concrete prepared from fresh aggregate showed the better performance regarding strength.

Concrete made with 100% recycled aggregates is weaker than concrete made with fresh

aggregates at the same concrete mix design. Strength reduction was 20%-30% of design

strength.

The workability of RAC is lower than FAC because the rate of the absorption capacity of RA is

higher than FA.

7.5

15.6 16.317.6

11.2

17.8 18.019.6

13.5

21.122.4 22.9

0.0

5.0

10.0

15.0

20.0

25.0

7 21 28 60

Co

mp

ress

ive

Str

eng

th (

MP

a)

Curing Period (Day)

Compressive Strength of Recycled Aggregate Concrete-

M21, 28, 32 Mpa

M 21

M 28

M 32

11.9

20.7 20.922.6

16.0

23.0

27.7 28.2

18.1

31.6 31.9 32.1

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

7 21 28 60Co

mp

ress

ive

Str

eng

th (

MP

a)

Curing Day

Compressive Strength of Fresh Aggregate Concrete - M21,

28, 32 Mpa

M 21

M 28

M 32

1st International Conference on Research and Innovation in Civil Engineering (ICRICE 2018), 12 –13 January, 2018, Southern University Bangladesh (SUB), Chittagong, Bangladesh ISBN: 978-984-34-3576-7

Page 6: AN INVESTIGATION ON PROCESSING AND PROPERTIES OF …€¦ · tested for absorption capacity, specific gravity, moisture content, unit weight, and FM. The specific gravity and absorption

CONCLUSION

Based on the laboratory investigations, the following conclusions are made:

1. Concrete strength from 17.5 ~ 23.0 MPa can be obtained using recycled coarse aggregate.

2. The water requirement for all the mixes is different and especially for mixing with recycled

coarse aggregates, so workability is poor then fresh aggregate concrete.

3. The density of concrete is another important factor. The results indicates that all the concrete

mixes with recycled aggregate have less density as compared to fresh aggregate concrete.

4. Recycled aggregate is not suitable where higher strength of concrete is required.

REFERENCE

1. Influence of Type and replacement Level of Recycled Aggregate on concrete Properties.

Yang, Keun -Hyeok, Chung, Heon -Soo and Ashour, Ashraf F. June 2008, ACI Materials

Journal, pp. V.105,No.3.

2. Standard Test Method for Relative Density (Specific Gravity) and Absorption of Fine

Aggregate. American Society for Testing and Materials, ASTM. West Conshohocken, PA,

2015, ASTM International, pp. DOI: 10.1520/C0128-15.

3. Mixture Proportioning. ACI Committee,211-91. 1991, Standard Practice for Selecting

Proportions for Normal, Heavyweight, and Mass Concrete (Reapproved 2009), p. 38.

4. Aziz, Dr M. A. ENGINEERING MATERIALS . Dhaka : s.n., 1995.

5. Sustainable Development of Concrete Technology. Mohammed, Dr. Tarek Uddin.

Dhaka : Dept. of Civil Engineering (UAP).

1st International Conference on Research and Innovation in Civil Engineering (ICRICE 2018), 12 –13 January, 2018, Southern University Bangladesh (SUB), Chittagong, Bangladesh ISBN: 978-984-34-3576-7