Document [original]

Removal of asbestos as an intrusive contaminant

from concrete construction waste

Rani Kumari Thakur Jha1 | Nico Zimmermann1 | Falk Schaudienst1 | Frank Ulrich Vogdt1

Introduction

To consummate the necessity of a growing world popula-

tion, the need for urban expansion, the connection be-

tween cities, and demand for the construction of buildings,

residences, paving, urban maintenance, roads, and train

lines are the least. The existing constructions need to be

updated according to the updated and environmentally

friendly construction laws, therefore rebuilding is often ob-

served. The execution of such extensive engineering

works requires the usage of millions of tons of natural re-

sources, for example, aggregates, cement, water, wood,

and various metals to name a few. To manage the need,

exploration of natural resources reserve is carried out

however, with this large amount of natural resource ex-

traction, potential environmental impacts must be consid-

ered. At the same time, the scarcity of virgin raw materials

has enhanced the importance of recycling building mate-

rials manyfold. The fast-growing need for construction and

demolition generates huge construction and demolition

waste (C&D waste). In general, the C&D waste amounts

are more than a quarter of the total generated solid waste

[1][2].To manage huge amounts of C&D waste and to be

able to be reused back in material flow is the absolute need

of the current time.

Since the demolition of buildings and other infrastructure

produces much more waste than construction activities,

demolition projects often create 20 to 30 times as much

waste as construction projects [3], the development of

processes to effectively reuse and recycle demolition ma-

terials is important for reducing landfilled C&D waste as

well as promoting circular economy. In the context of

demolition waste, Crushed Concrete in particular is a pop-

ular recycling material. Recycling of concrete is often re-

strained due to the hazardous impurity contents, that are

hard to separate as well as to recycle. Particularly, asbes-

tos contamination came into focus after law enforcement

and as an impact of various studies worldwide. Asbestos

is found in various mineral products such as wall reinforce-

ments, spacers, and tile adhesives, and poses unusually

difficult to detect and separate as they form a strong bond

with concrete.

As asbestos is categorized as carcinogenic and thus dan-

gerous for human health therefore a ban is imposed on

asbestos use since 1993 in Germany. The complete exclu-

sion of asbestos must be observed in any new construc-

tion, as well as the rejection of asbestos in any of its fi-

brous configurations from the recycling route of concrete

is mandatory. Eliminating asbestos in concrete recycling

will result in increased concrete recycling with a better cir-

cular material flow cycle.

Using the deconstruction of the quay wall as an example,

this paper presents different life cycle assessments for

practicable sustainable options that focus on the potential

CO2 footprint of the entire process from detection to the

ORIGINAL ARTICLE

Abstract

The construction industry is the world's largest and fastest-growing industry due to

the increase in population, standards of living, and the higher demand for infra-

structure. This fast growth generates huge amounts of construction and demolition

waste (C&D waste), which amounts to more than 25% of the total generated waste,

which has become a serious environmental challenge that needs to be addressed.

The asbestos content in C&D waste poses a health risk and is entitled to special

care, however, disposal of asbestos as hazardous waste is the only option by law.

The present paper suggests the selective demolition of asbestos-containing demol-

ished waste rubble to be disposed of in compliance with all local and state regula-

tions and proposes non-asbestos rubble fraction to be recycled as an alternative

sustainable management option that mitigates different adverse environmental im-

pacts of the presently used conventional C&D waste management method.

Keywords

Asbestos, life cycle assessment, concrete waste, recycling, global warming potential

Correspondence

Dr. Rani Kumari Thakur Jha

Technische Universität Berlin,

Geb.TIB 13b, Sekr. TiB1-B3,

Gustav-Meyer-Allee 25,13355

Berlin, Germany

Email: r.thakur.jha@tu-berlin.de

1 Technische Universität Berlin,

Berlin, Germany

Proceedings

in civil engineering

https://doi.org/10.1002/cepa.2871 wileyonlinelibrary.com/journal/cepa

ce/papers 6 (2023), No. 6

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in

any medium, provided the original work is properly cited

1004

removal of asbestos and recycling of concrete. The appli-

cation of Life Cycle Assessment in the building sector has

improved a lot in recent years [4]. The increased interest

is due to the comprehensiveness of the LCA method for

considering many aspects of the environmental impacts of

a building [5]. This paper uses the ReThiNK EPD app (de-

veloped by Kiwa Deutschland) to quantify the potential

CO2 footprint and other environmental impact factors.

Material and method

2.1 Life cycle assessment

There are different ways to gauge the amount of pollution

emitted during every step of the life cycle of a building,

however, the current paper focuses on the demolition and

end-of-life stage in the construction industry. The Life Cy-

cle Assessment (LCA) is an internationally standardized

methodology for environmental assessment, applied to

evaluate the environmental impact of a product or system

[6][7].

This methodology can be used for modeling and simulation

of waste management scenarios, in the present paper the

ReThiNK app [8] is used for the assessment, while the re-

quired data for the life cycle inventory is either from the

literature, the lab-scale experiments or surveying the re-

cycling facilities [9][10].

2.2 Goal and Scope

The present study aims to quantify different environmen-

tal impact factors in the process of recycling the demolition

waste produced, to assess impact categories for the two

scenarios: selective demolition of asbestos-containing

segment followed by wrecking the whole structure and re-

cycling the non-asbestos part whereas the asbestos parts

end up in controlled landfills; compared with asbestos con-

tained construction that demolished at once and ends up

at landfill that deal with hazardous waste: the scenarios

are pictorially described in Fig.1. The focal point is the se-

lective demolition to restrict asbestos content to go further

in material flow.

2.3 System Boundary

In the first step of LCA, the boundaries of systems are de-

fined to identify inputs and outputs, to consider all pro-

cesses, the input data on energy flows and material flows,

and output data related to specific issues. In the present

work, the system boundary falls into the end-of-life cate-

gory, which comprises the demolition phase and evalua-

tion of the recycling possibilities.

2.4 Inventory analysis

The inventory phase is collecting all sorts of information

using surveys, calculations, and analyzing comparatively

with studies from literature, for all the sectors involving

materials, energy, and fuels. After data inventory collec-

tion and data normalization to the functional unit, the en-

vironmental impact was evaluated.

The designated demolition company and recycling facility

were interviewed, and a survey was carried out, moreover,

machine specifications and construction guidelines for spe-

cific asbestos-containing parts used were referenced for

the literature data needed for the analysis.

2.5 Life cycle impact assessment

Life cycle impact assessment is the phase in the LCA aim-

ing at understanding and evaluating the magnitude and

significance of the potential environmental impacts of a

product system. The life cycle of a product ranges from

resource extraction via material processing, manufactur-

ing, and product use or service delivery, to recycling, and

the disposal of any remaining waste [11]. In the present

paper Global warming potential, ozone layer depletion,

acidification of soil and water, eutrophication, and human

toxicity are the environmental impact factors that are

taken into account and assessed in the case of demolition

and disposal or recycling of asbestos-contained construc-

tion.

Result and Discussion

Fig. 1 illustrates the two different scenarios with their sys-

tem boundaries addressed and discussed in this paper.

Scenario 1 depicts the demolition of a concrete structure

that contains asbestos, after the inspection, the majority

of dismantled concrete rubbles were landfilled in different

landfill sites as per their hazardous nature. Whereas the

second scenario describes the demolition of asbestos-con-

tained parts after inspection that is disposed of in a con-

trolled landfill designated for hazardous wastes leaving the

non-asbestos concrete rubbles to be further recycled and

reused.

Traditional demolition practices in which all building mate-

rials are mixed create a waste stream that is difficult and

costly to recycle, in contrast, the separation of materials

at the demolition site through selective demolition or other

means is often the most effective way to ensure a clean,

uncontaminated product [12]. Since carcinogenic asbestos

is involved in the present work, precise separation is

obliged and proper handling is imposed by the law.

Figure 1 System boundaries for the scenarios

3.1 Global Warming Potential

Global warming potential, abbreviated as GWP, is a term

used to describe the relative potency of a greenhouse gas,

taking into account how long it remains active in the at-

mosphere.

Fig: 2 shows the global warming potential of both ad-

dressed scenarios, as calculated with the help of ReTHiNK

web-based LCA software.

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Figure 2 Global warming potential

The global warming potential for scenario 1 is 68,190876

kg CO2eq whereas for scenario 2 it is 87,7916149 kg

CO2eq. It is evident that the recycling of a non-asbestos

fraction of the demolished waste contributes an additional

amount of GWP, however, a more circular material can be

achieved with the recycling and reuse of non-asbestos de-

molished waste rubble i.e in scenario 2.

3.2 Ozone layer depletion

The ozone-depleting potential is a measure of how much

damage a chemical can cause to the ozone layer compared

with a similar mass of trichlorofluoromethane (CFC-11).

CFC-11, with an ozone-depleting potential of 1.0, is used

as the base figure for measuring ozone-depleting Potential

[13]. landfilling of huge C&D waste has an adverse effect

on ozone layer depletion as one of the foremost environ-

mental impacts. With a huge percentage of the pollution

that can be attributed to the construction industry on a

global scale reaching 50% in landfill waste, ozone deple-

tion, and climate change gases, it is pivotal that the con-

struction and demolition industry move forward in imple-

menting preventive measures to decrease catastrophic

effects [14].

Fig.3 shows the ozone layer depletion potential of both

scenarios assessed in the present paper. Scenario 1 has

the value of 1,32E-05 Kg CFC-11 Equivalent while scenario

2 has a little high potential of 2,72E-05 Kg CFC-11 Equiv-

alent. The slight increase in the second scenario is given

the fact of the additional recycling process.

Figure 3 Ozone layer depletion

With a little high ozone layer depletion potential Scenario

2 limits landfill activities by choosing to recycle non-asbes-

tos concrete rebel fraction to be reused further in the

building industry, leaving behind only the asbestos part to

be landfilled in a controlled, designated facility, and thus

scenario 2 is a better situation to opt and practice.

3.3 Acidification of soil and water

Soil acidification is a process where the soil pH decreases

over time and effect adversely soil and subsoil. The pro-

cess is accelerated by human activities, unconscious agri-

cultural activities, uncontrolled waste management, and

dated landfilling actions to name a few.

Fig.4 shows the soil and water acidification potential of

both scenarios assessed in the present work. Scenario 1

has the value 0,45689576 Kg SO2 Equivalent, whereas a

small increased value of 0,68325713Kg SO2 Equivalent is

for scenario 2. Scenario 2 comprises a recycling activity

and therefore it has a slight increase in acidification po-

tential, however, in scenario 1 almost all the concrete rub-

ble ends up in landfill sites that deal with asbestos and

other hazardous material. It has been reported that more

than 50% of construction and demolition waste is depos-

ited in landfill sites, which forms a real environmental chal-

lenge for every country, that needs to be addressed [15].

Figure 4 Acidification of soil and water

The enormous requirement of land for landfill purposes for

growing demolition waste is a previously pointed problem,

in addition, the probability of high pH leachate leaching

from these landfill sites is another threatening issue to

handle over time. Therefore, it is beneficial to recycle con-

crete rubble to enhance circularity rather disposing at a

landfill site.

3.4 Eutrophication

An overabundance of nutrients, primarily nitrogen, and

phosphorus in a water body leads to a process called eu-

trophication that has harmful health and environmental ef-

fects.

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Figure 5 Eutrophication

The eutrophication potential is presented in Fig. 5. The eu-

trophication potential for scenario 1 is 0,10328768 Kg PO4

Equivalent whereas for scenario 2 it is 0,14671303 Kg PO4

Equivalent. The difference in eutrophication potential for

both scenarios is negligible even though the second sce-

nario steps up substantially in circularity and as a result,

the asbestos-free material flow can be achieved.

3.5 Human toxicity

The human toxicity potential (HTP), is used to weigh emis-

sions inventoried as part of a life-cycle assessment, a cal-

culated index that reflects the potential harm of a unit of

chemical released into the environment. As asbestos ex-

posure has carcinogenic potential and is thus banned from

a major fraction of the developed world, quantifying the

human toxicity associated with both scenarios is needful

to perform.

Figure 6 Human toxicity

Fig.6 illustrates the human toxicity (cancer) potential for

scenario 1 is 4,91E-07 CTUh while a slight increase is evi-

dent for scenario 2 and the value is 5,92E-07CTUh. The

slight increase in toxicity potential resulting from the var-

ious activities involved in recycling and transporting the

nonasbestos demolished

fraction, however, the recycling of non-asbestos fraction

i.e, the asbestos-free material flow orients well with the

aim of the present work as well as satiate the growing

need for production of energy incentive construction ma-

terials.

Conclusion

Life cycle assessment with the help of the ReTHiNK app of

asbestos-containing concrete demolition waste was done

and demonstrated based on the primary data collected, for

five main environmental impact categories. The study

demonstrates two different scenarios, where in the first

the major fraction of demolished waste ends up in a con-

trolled landfill while the second one fosters the recycling

of non-asbestos fraction and landfill only the asbestos-

contaminated rubble. The five environmental impact fac-

tors that are assessed in the present study are slightly in-

creased for the second scenario, however, the increased

value corresponds to the recycling activity which facilitates

better circularity in a bigger perspective.

The removal of carcinogenic asbestos content from the

material flow can be achieved by selective demolition and

disposal in compliance with all local and state regulations

followed by the recycling of non-asbestos C&D waste con-

tributes significantly to achieving sustainable development

through the following gains:

• Reducing the demand for primary materials by re-

placing them with secondary recycled (asbestos-

free) materials.

• Cut down energy consumption that corresponds

to primary materials extraction, transport, and

production energy costs, and reuses waste that

can otherwise be lost to landfills and may lead to

the severe environmental problem over an ex-

tended period such as toxic leachate leaches to

soil, or water. Consequently, the land used, and

several long-term adverse environmental effects

can be avoided by limiting the landfilled waste

quantity.

• Although landfills will continue to be an important

disposal option, especially for the asbestos-con-

tained fraction until the proper recycling tech-

nique is developed and practiced for the same, the

recycling of C&D waste will reduce the possible

environmental risk by minimizing the amounts

going to landfilling.

Acknowledgement

We are grateful for the BMBF, which has supported us fi-

nancially within the framework of the FONA strategy. We

would also like to express our special thanks to the follow-

ing companies and project partners: Kluge Sanierung

GmbH; Buhck Umweltservices GmbH & Co. KG and

WESSLING GmbH, who supported the work by providing

data on their demonstration project. We would like to ex-

tend our gratitude to Kiwa Deutschland for developing and

providing ReTHiNK: a web-based LCA and EPD tool.

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