variation in physical and environmental properties …

VARIATION IN PHYSICAL AND ENVIRONMENTAL PROPERTIES

OF RECYCLED CONCRETE AGGREGATES FROM C&D WASTE IN

DELHI

Christian J. Engelsen (1), Harsha Meenawat (3), Arun Kumar Sharma (2), Gaurav

Bhatiani (3), Kshemendra Nath P (4), Monica S. Nodland (1)

(1) SINTEF Building and Infrastructure, Norway

(2) IL&FS Environmental Infrastructure & Services Ltd

(3) IL&FS Academy of Applied Development

(4) Resilient Energy Pvt. Ltd.

Abstract

Construction and demolition waste (CDW) is one of the biggest waste streams globally. The

heavy inorganic part (from concrete and masonry) could be processed and refined into recycled

aggregates. The Burari C&D waste recycling facility is located in the north of Delhi and is

currently one of three recycling plants operating in Delhi. In relation to the Indo-Norwegian

quality assessment program, the physical and environmental properties have been studied.

The physical, chemical and environmental properties determined over time were found to be

relatively stable during the extensive sampling periods. Most of the parameters were complying

to the requirements in IS 383. For some parameters, such as specific gravity and fines content,

small modifications in the recycling process will decrease the fine particle content to the desired

level. However, RCA with higher contents can be used in other applications like for example

concrete block production.

The contents of inorganic and organic dangerous substances were found to comply with

the strictest soil criteria (class I) in Norway. Cr(total) exceeded the criteria. However, most of

the chromium was present on the trivalent form, Cr(III), which has low solubility in the neutral

to mildly basic pH region.

Keywords: Recycled aggregates, mechanical and environmental properties

International Conference on Sustainable Materials, Systems and Structures (SMSS 2019)

280

New Generation of Construction Materials20-22 March 2019 – Rovinj, Croatia

1. INTRODUCTION

Construction and demolition waste (CDW) is one of the biggest waste streams globally. The

heavy inorganic part (from concrete and masonry) could be processed and refined into recycled

aggregates. This type of aggregates could substitute natural aggregates in a range of user

applications such as road construction, landscaping and concrete production. This will save

natural resources, decrease transportation, reduce landfilling and bind CO2 through increased

carbonation.

The revised framework for waste management in the EU [1], which was adopted in 2008,

includes a target for recovery of CDW. Within 2020, the preparing for re-use, recycling and

other material recovery of non-hazardous construction and demolition waste (excluding

naturally occurring material) shall be increased to a minimum of 70 % by weight. The target

was added during the final negotiations of the Directive text and instructions for verifying

compliance were established in 2011 [2]. Norway has implemented the WFD and must comply

to this target through the partnership of the European Economic Area. The directive is intended

to be an overall key driver for circular driven economy for C&D waste. In India, the estimates

for the annual CDW generation vary from 50-500 million tons. However, more accurate figures

could be calculated for Delhi where the generation is around 3000-4000 tons per day. Thus, it

is challenging to meet the demands for treatment and recycling.

In 2016, Central Public Works Department (CPWD) under Ministry of Housing & Urban

Affairs (MoH&UA), Govt. of India has signed a Memorandum of Understanding (MoU) with

the Foundation for Scientific & Industrial Research (SINTEF, Norway). The institutions agree

to facilitate collaboration on all aspects of waste management and building technology with

special emphasis on best available technology on recycling of construction and demolition

waste. The purpose of the MoU is to incept a 4-years institutional cooperation project between

CPWD and SINTEF on capacity building and technical support on treatment and utilisation of

construction and demolition waste in India. The Indo-Norwegian project (C&D-WIN) started

in 2017 and is supported by the Royal Norwegian Embassy New Delhi. It will continue to the

end of 2020.

In the present study, recycled concrete aggregates (RCA) produced in recycling facility in

Delhi have been assessed for variation in essential properties (density, water absorption, etc.)

over time. The aggregates produced may be suitable for bound (e.g. concrete production) and

unbound use (e.g. road construction). The study was part of the C&D-WIN project.

2. MATERIAL AND METHODS

2.1 Description of the feedstock material and sampling procedure

The sampling of RCA was conducted at Burari C&D waste recycling plant in Delhi. This

plant has installed the wet recycling processes (CDE Aggmax ™ system). In addition, the plant

has a dry processing support line for feedstock that contains mostly concrete rubble. The

sampling was conducted in the period of November 2017 to February 2018. The feedstock

material contained largely concrete and concrete masonry units intermixed with some soil.

Small fractions of bricks and ceramics could be found occasionally. These quantities were

initially evaluated to have low influence on the final RCA properties due to their relative small

share.


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The sampling represented a daily production shift by collecting sub-samples from the

conveyer belts every 1-2 hour during the whole working shift, i.e. 5 sub-samples. These samples

were mixed and homogenised to one daily bulk sample. The sampling program was developed

by SINTEF who was present at site together with Bureau Veritas during the sampling period.

A total of 4 daily bulk samples were prepared and analysed during the sampling period at

Bureau Veritas in Delhi and at SINTEF and ALS Laboratory in Norway.

2.2 Physical properties determined in RCA

The cement paste content was assessed for all samples since the mortar content in RCA often

represents the weaker bonding in the interfacial transition zone (ITZ) between the RCA particle

and the cement paste [3]. It has been shown earlier that the acid soluble content can serve as an

indicator for the cement paste content in RCA [4]. Hence, the acid soluble content was

determined according to the procedure described in [4]

In addition, the following properties determined according to Indian standard IS 2386 [5] will

be presented:

- Classification of coarse RCA

- Particle grading

- Shape of coarse aggregates (combined elongation and flakiness index)

- Specific gravity and water absorption

- Aggregate abrasion value of coarse aggregates, by Los Angeles (LA)

2.3 Chemical and environmental properties of RCA

The RCA samples were reduced in volume by splitting, quartering, crushing and

pulverization. The reduction of the laboratory samples to test samples and to final test portions

was conducted according to NS-EN932-2 and NS-EN 15002.

The presence of following organic and inorganic substances was determined in the RCA

samples; polychlorinated biphenyl (ΣPCB-7), polycyclic aromatic hydrocarbon (ΣPAH-16),

BTEX (benzene, toluene, ethylbenzene, xylene), total hydrocarbons (THC), total organic

content (TOC), As, Cd, Cr(total), Cr(VI), Cu, Pb, Hg and Ni.

GC-MS with selective ion monitoring (SIM) was used to determined ΣPCB-7, ΣPAH-16 and

BTEX. THC were analyzed using GC with flame ionization detector. Heavy metals were

analyzed by Inductively coupled plasma (ICP). In addition, the acid soluble contents of sulphate

and chloride were determined according to EN 1744-1 and IS 14959-P-2, respectively.

3. RESULTS AND DISCUSSION

3.1 Acid soluble content

The acid soluble content is shown in Table 1 and was found to be in the region of 19-33%.

These contents were considered to be slightly higher than what normally can be found in only

concrete rubble [4]. The presence of different types of mortar from masonry usually contribute

to increase the cement paste content. Furthermore, the acid soluble contents were inorganic in


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nature as the TOC levels were less than 1%, as will be shown in chapter 3.4. Hence,

considerable amounts of cement paste were present in the RCA. In addition, it can be seen that

the cement paste is accumulating more in the finest particle size, i.e. in RCA 0/3 mm. It is

emphasised that these recycled aggregates were produced from a dry process line. In a wet

recycling process, a significant amount of the cement paste can be removed by washing and

scrubbing.

Table 1: Acid soluble content given weight % as the arithmetic mean of 3 replicates

Daily sampling number RCA 0/3 mm RCA 3/10 mm RCA 10/20 mm

1 not determined 26 not determined

2 27 25 23

3 32 29 19

4 33 29 27

3.2 Particle grading and classification of coarse aggregates

The sieving analysis revealed that the RCA 10/20 mm was entirely according to the

requirements in IS 383 [6]. Regarding the samples RCA 0/3 mm and RCA 3/10 mm, the content

of particles less than 75 µm was typically higher than the criteria of 10% and 1%, respectively.

Decreasing the fines content by for example a washing step will most likely result in compliance

with IS 383 for RCA 0/3 mm (Zone-II) and RCA 3/10 mm.

The classification of coarse aggregates (3/10 mm and 10/20 mm) showed that only small

amounts of clay masonry was found in all tested samples. The content of concrete, mortar and

unbound masonry was in the region of 40-50%. Furthermore, bitumen, glass, metal, wood and

gypsum were not found.

3.3 Other important physical and chemical properties

Based on previous analysis (cement paste content and classification), some variation

between the sampling periods was found. The impact of this variation on the other important

properties are shown in Figure 1. Water absorption and specific gravity were found to be

relatively stable, except for one sample. The results also showed the expected difference

between the three different particle sizes, i.e. highest density and lowest water absorption for

the coarsest fraction. Furthermore, the combined elongation and flakiness, aggregate abrasion

(by LA) and the acid soluble sulphate content were evaluated to be relatively stable over the

sampling periods. The acid soluble chloride content varied but at a low concentration level.

Some chloride results in the sampling period 2, were found to be around and insignificantly

above the IS 383 criteria of 0.04 %. Except for the specific gravity of RCA 0/3 mm, the results

complied to IS 383.

It is emphasised that part removal of the fines will lead to lower chloride content and

increased specific gravity, in particular for the RCA 0/3 mm fraction. Decreasing the fines

content without installing a washing step, may be conducted by installing a by-pass or reduce

the entering of overflow materials into the recycling process.


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Figure 1: Variation in time of important properties of RCA

3.4 Environmental assessment

Results from the analyses of organic substances and heavy metals in the samples are given

in Table 2. Except for Cr(total), the results obtained complied with the Norwegian soil quality

criteria (class 1) issued in the Norwegian Pollution Control Regulation. These criteria were

originally developed for handling of polluted soil. However, they are currently being used to

assess the environmental ability to recycle C&D waste. RCA complying to class 1 can normally

be used without restrictions above groundwater and not directly placed into sea water or fresh

water resources. Regarding the Cr(total) and Cr(VI) concentrations, only small quantities of the

1,20

1,40

1,60

1,80

2,00

2,20

2,40

2,60

2,80

1 2 3 4

Spe

cifi

c gr

avi

ty (

g/c

m3)

Sampling period number

Specific gravity

10/20 mm

3/10 mm

0/3 mm

IS 383 minimum0,0

2,0

4,0

6,0

8,0

10,0

12,0

1 2 3 4

Wa

ter

ab

sorp

tio

n (%

)


Water absorption

10/20 mm3/10 mm0/3 mmIS 383

05

1015202530354045

1 2 3 4

Ind

ex (%

)


Combined elongation and flakiness

10/20 mm

3/10 mm

IS 383

0

20

40

60

80

100

1 2 3 4

LA (%

)


Ressistance to fragmentation (LA)

10/20 mm3/10 mmIS 383 for wearing surfaces (30%)IS 383 no wearing (50%)

0,000,100,200,300,400,500,600,700,800,90

1 2 3 4

SO3

(%)


Acid soluble sulphate

10/20 mm 3/10 mm

0/3 mm Norwegian limit

0,000,010,010,020,020,030,030,040,040,05

1 2 3 4

Cl (

%)


Acid soluble chloride

10/20 mm3/10 mm0/3 mmIS 383


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latter were determined. Hence, most of the chromium content were likely on the trivalent form

Cr(III). This chemical form has low solubility compared to the highly soluble hexavalent

chromium, often seen as oxyanions (e.g. CrO42-) [7].

Table 2 Content of inorganic and organic substances determined in the RCA samples

Substance Total concentration (mg/kg)a

RCA 0/3 RCA 3/10 RCA 10/20 Soil criteriab

As 4.8 - 4.9 3.8 - 6.1 3.4 - 5.6 8

Cd 0.10 - 0.18 < 0.05 - 0.12 0.07 - 0.12 1.6

Cr(total) 120 - 147 100 - 165 117 - 160 50

Cr(VI) 0.9 - 1.6 0.3 - 1.0 < 0.20 - 0.6 2

Cu 25 - 31 18 - 39 19 - 31 100

Pb 19 - 20 15 - 23 14 - 19 60

Hg 0.011 - 0.027 < 0.01 - 0.02 < 0.01 1

Ni 21 - 23 21 - 24 21 - 25 60

Zn 59 - 68 48 - 56 48 - 82 200

Sum PCB-7 n.d. - 0.02 n.d. n.d. 0.01

Sum PAH-16 0.06 - 0.09 n.d. - 0.9 n.d. 2

Benzen < 0.010 < 0.010 - 0.02 < 0.010 0.01

Toluene < 0.040 < 0.040 < 0.040 0.3

Enthylbenzen < 0.040 < 0.040 < 0.040 0.2

Xylene < 0.040 < 0.040 < 0.040 0.2

THC > C5-C6 < 2.5 < 2.5 < 2.5 7

THC > C6-C8 < 7.0 < 7.0 < 7.0 7

THC > C8-C10 < 10 < 10 < 10 10

THC > C10-C12 < 10 < 10 < 10 50

THC > C12-C16 < 10 < 10 < 10

THC > C16-C35 10 - 130 40 - 150 27 - 46 100

Sum > C12-C35 10 - 130 40 - 150 27 - 46 100

TOC 8000 - 9000 2000 - 7000 4000 - 5000 - a n.d. = not detected b Soil criteria for sensitive land use issued in Norwegian Pollution Control Regulation

4. RECOMMENDATIONS

The results suggest that the output from Burari to be broadly compliant with IS 383.

Hence, efforts should be made by all stakeholders to increase the usage of recycle materials.

Furthermore, two important issues need consideration. Firstly, replicating success of Burari in

other cities with particular emphasis on lessons learnt, so as not to reinvent wheel after almost

a decade of operational experience with CDW facilities. Secondly, ensuring financial viability

of CDW facilities will require emphasis on continuous product testing, standardization and

certification through independent channels to enhance confidence among the construction


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contractors. This study is a step in this direction. Burari should take steps, as suggested, to

further enhance quality of its output to serve more advanced needs and collaborate with large

and sophisticated construction companies.

5. CONCLUSION

The results show that relatively stable physical, chemical and environmental properties were

determined during the extensive sampling periods. Most of the parameters were complying to

the requirements in IS 383. For some parameters like specific gravity and fines content, small

modifications in the recycling process could easily decrease the fine particle content to the

desired level. However, RCA with higher contents of fines have shown excellent properties, in

for example, concrete block production.

The contents of inorganic and organic dangerous substances were found to comply with the

strictest soil criteria (Class I) in Norway. Although the Cr(total) exceeded the criteria, most of

the chromium was present on the trivalent form, Cr(III), which has low solubility in the neutral

to mildly basic pH region.

ACKNOWLEDGEMENTS

The authors are grateful to Nivedita Borthakur and Aanchal Susheen for assistance in sampling and

data entry. The study is part of the Indo-Norwegian project on "Treatment and recycling of C&D

waste in India" supported by the Royal Norwegian Embassy New Delhi.

REFERENCES

[1] WFD (Waste Framework Directive), 2008. Directive 2008/98/EC of the European Parliament and

of the Council of 19 November 2008 on waste and repealing certain Directives. OJ L 312,

22.11.2008.

[2] Arm, M., Wik, O., Engelsen, C.J., Erlandsson, M., Hjelmar, O. and Wahlström, M., How does the

European recovery target for construction & demolition waste affect resource management?, Waste

Biomass Valor 8 (2017) 1491–1504.

[3] Ng, S. and Engelsen, C.J., 2018. Construction and Demolition wastes, In: Waste and Supplementary

Cementitious Materials in Concrete: Characterisation, Properties and Applications. Editors: Rafat

Siddique and Paulo Cachim, Elsevier publication.

[4] Engelsen, C.J., van der Sloot, H.A., Wibetoe, G., Stoltenberg-Hansson, E., Petkovic, G. and Lund,

W., 'Release of major elements from Recycled Concrete Aggregates and geochemical modelling',

Cement and Concrete Research, 39 (5) (2009) 446-459.

[5] IS 383, Indian Standard - Methods of test for aggregates for concrete, 1967 (reaffirmed 2007),

Bureau of Indian Standards 2007.

[6] IS 2386, Indian Standard – Coarse and fine aggregate for concrete - Specifications, 2016 (third

revision), Bureau of Indian Standards 2016.

[7] Engelsen, C.J., van der Sloot, H.A., Wibetoe, G., Justnes, H., Stoltenberg-Hansson, E., Lund, W.,

'Leaching characterisation and geochemical modelling of minor and trace elements released from

recycled concrete aggregates', Cement and Concrete Research 40 (12): 2010: 1639-1649.


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