Construction and demolition waste as a resource for sustainable, very lowenergy buildings

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International HISER Conference on Advances in Recycling and Management of Construction and Demolition Waste

21-23 June 2017, Delft University of Technology, Delft, The Netherlands

92 Construction and demolition waste as a resource for sustainable, very

low-energy buildings

Ivana Banjad Pečur

1

, Marina Bagarić

2

, Bojan Milovanović

3

and Ivana Carević

4 1,2,3,4

University of Zagreb, Faculty of Civil Engineering, Department of Materials, Andrije

Kačića Miošića 26, 10000 Zagreb, Croatia,

E-mail: banjadi@grad.hr; mbagaric@grad.hr; bmilovanovic@grad.hr; icarevic@grad.hr

Abstract

The framework of the research presented in the paper is a project oriented to promote the use

of construction and demolition waste (CDW) as a new resource for constructing sustainable

and very low-energy buildings.

Intensive research activities have been carried out in application of recycled concrete and

recycled brick as a replacement of natural aggregate in concrete. Based on conducted

mechanical, durability and thermal testing of recycled aggregate concrete, replacement ratio

of natural aggregate by 50% was determined as optimal. Research resulted with development

of an energy and resource efficient construction product ECO-SANDWICH® - ventilated

precast concrete sandwich wall panel with integrated formaldehyde-free mineral wool

insulation. ECO-SANDWICH® wall panel is a benchmark construction product that allows

very low energy design and retrofit of buildings; therefore, it can be coupled with an exigent

need to improve energy performance of the building stock in the EU and neighbouring

countries. Storage of recycled materials from CDW in concrete and production of a new high

quality construction product can add value to CDW and contribute to closing the loop of

product lifecycles which is the basis of a circular economy. The last part of the paper presents

the first application of ventilated precast concrete sandwich wall panels produced with

recycled CDW and an overview of current research on its hygrothermal properties.

Keywords:

construction and demolition waste, recycled aggregate, energy efficiency,

precast sandwich panel, ECO-SANDWICH

®

Introduction – Why CDW?

Increasing demand on energy efficiency and natural resources conservation, caused by energy

poverty and depletion of natural resources, is strongly challenging the construction sector as

one of the top consumers. Europe has set the legal framework and established the

requirements that all Member States are obligated to fulfill regarding the energy efficiency in

building sector [1], and management of construction and demolition waste (CDW) [2]. How

to transform those ˮlimitationsˮ into opportunities and advantages? Can CDW gain added

value and be used as a resource for production of new construction products that will satisfy

all regulations, fit into concept of sustainability and ensure lower energy consumption? Can

CDW be one of factors that drive revival of European economy and construction sector? Can

CDW be a milestone in a life cycle of buildings? Those were the guiding principles in

extensive research that has been carried out within the ˮECO-SANDWICH Energy Efficient,

Recycled Concrete Sandwich Façade Panelˮ project funded by CIP-Eco Innovation.

Conducted research resulted with the development of ECO-SANDWICH

®

(ES

®

) panels with

high degree of recycled materials obtained from demolition of existing buildings and

production process of construction materials.

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93 Comprehensive approach consisting of designing out and minimizing waste from root cause,

incorporating reused and recycled materials into new enhanced construction products and

managing the end of life reuse and recycling of assets will help achieve a circular economy

[3]. Circular economy offers an opportunity to boost global competitiveness, foster

sustainable economic growth and generate new jobs [4].

Eco-sandwich

®

panel – Bank of CDW

ES

®

panel is an innovative

precast sandwich wall panel

with integrated glass wool

core insulation allowing very

low energy design and retrofit

of buildings. It consists of two

concrete layer interconnected

through

stainless

lattice

girders (Fig. 1).

a) b)

Figure 1. ES® panel: a) model, b) detail of connection with concrete slab

Innovation lays in using CDW as a resource for producing concrete layers, formaldehyde-free

core insulation and ventilation layer for preventing possibility of water vapour condensation.

The inner (self-load bearing) layer is made of recycled concrete aggregates (RCA) while the

outer façade layer is made of recycled brick aggregates (RBA). ES

®

represents possible

technological solution for fast construction of very low energy or passive house standard

buildings on a large scale, thus minimizing environmental impacts. During the project

duration, the first step was to determine the most favorable replacement ratio of virgin

aggregate with CDW in concrete mixes from the aspects of best balance between mechanical,

durability and thermal properties. The second step was to deal with market uptake of the

developed solution. Based on optimization, the replacement ratio of 50% of virgin coarse

aggregate was chosen as optimal for the ES

®

panels [5, 6].

Mechanical properties. Compressive strength of RCA concrete is classified as C30/37 and

RBA concrete as C25/30, respectively [5, 6].

Thermal properties: Mean thermal conductivity of RCA concrete is 0,858 W/mK and RBA

concrete 0,746 W/mK, respectively. When comparing it with literature values of concrete

with approx. the same density, it can be concluded that the RCA and RBA concretes have

13–27% and 29–40% lower thermal conductivity [5, 6].

Fire resistance. ES

®

can withstand exposure to fire 90 min, which classifies its fire

resistance as EI90 [8]. Detailed results of mechanical, durability and thermal testing are

published elsewhere [5, 6]. They are also visible in ES

®

Declaration of Performance,

accompanied with CE mark.

Application of ES

®

: The

first application of innovative

ES

®

panels is a 3-storey

family house (A+ energy

class) constructed in 2016

within

socially-supported

housing program in City of

Koprivnica,

Republic

of

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94 Only in Europe, over 750 million m

3

of concrete is produced annually, which rounds up to 4

tons of concrete per capita [7]. Having in mind that aggregate accounts for 60-80% of the

volume and 70-85% of the weight of concrete, it’s clear that there is a tremendous potential

for incorporating CDW into concrete, thus reducing the amount of disposed CDW and

excavated raw materials. In case of ES

®

panels total amount of 1759 kg of aggregate was

used per 1 m

3

of concrete, of which 879.5 kg was recycled aggregate. At European level, that

would mean hundreds of billions of kg of recycled aggregate per year. In that sense, buildings

can be considered as materials bank.

Current Research of ES

®

– How it actually performs?

The question arises whether, properties at material level are sufficient to predict performance

of construction product at large scale in real environment? Particularly in case of new

innovative product. Building envelope can be considered as building ˮskinˮ which is exposed

to loads from the exterior and interior environment and tries to achieve hygrothermal balance.

This so called hygrothermal performance implies a combined heat, air and moisture transfer.

Moisture and heat transfer reflects by temperature and moisture content variations within the

characteristic layers of envelope. It is important to highlight that 75-90% of all construction

damage is caused by moisture [9]. Künzel et al. [10] emphasize the necessity of knowing the

hygrothermal properties of concrete since the moisture is a key factor influencing the

pathology and energy behavior of concrete elements. Currently, there is a lack of knowledge

on hygrothermal performance of recycled aggregate concrete at material level and ventilated

precast sandwich panels at large scale level. To gain a better insight, a program of

experimental monitoring on hygrothermal performance of a building envelope constructed

with ES

®

panels in Koprivnica is designed (Fig. 3).

Figure 3. Scheme of hygrothermal monitoring system in Koprivnica

Conclusion

Buildings offer a great opportunity to incorporate a large amount of CDW, acting as a

materials bank. This can result with significant reduction of CDW disposal, raw materials

excavation, environmental footprint, giving a CDW added value and development of new,

more sustainable construction products. Additionally, it can also be one of triggers for

construction sector in terms of new jobs and market expansion. Practical application resulting

from scientific research is the key towards stronger economy and a more competitive market.

ES

®

panel is an example of possible ways of embedding circular economy thinking into the

built environment. Next step ahead is obtaining information on real-time hygrothermal

performance which can give directions how to design smart buildings, i.e. optimizing and

improving building performance in-time by taking into account envelope behavior.

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95 References

[1] European Parliament, 2010. Council of the EU: Directive 2010/31/EU of the European

Parliament and of the Council of 19 May 2010 on the energy performance of buildings

(recast), OJEU L153/13

[2] European Parliament, 2008. Directive 2008/98/EC of the European Parliament and of the

Council of 19 November 2008 on waste and repealing certain Directives, OJEU L312/3

[3]

BRE

Buzz,

http://brebuzz.net/2017/03/03/buildings-as-materials-banks-enabling-a-circular-way-of-building/ ; visited 21

st

March 2017

[4] European Commission, 2015. Communication from the Commission to the European

Parliament, the Council, the European Economic and Social Committee and the Committee

of the Regions, Closing the loop – An EU action plan for the Circular Economy, COM(2015)

614 final

[5] Alagusic, M.; Milovanovic, B.; Banjad Pecur, I., 2016. ‘’Recycled aggregate concrete –

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Advances in Cement and Concrete Technology in Africa Proceedings 2nd International

Conference, Dar el Salaam, pp. 253-262

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nearly zero-energy buildings’’, Magazine of Concrete Research, 2015 67(11), pp. 575-584

[7] Bjegović, D., Štirmer N., Serdar M., 2010. ‘’Ecological Aspects of Concrete Production’’,

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[8] Banjad Pečur, I.; Gabrijel, I.; Milovanović, B.; Carević, I., 2014. ‘’ Ispitivanje na požar

novog inovativnog predgotovljenog fasadnog elementa’’, Proceedings of 4th International

Scientific Conference on Safety Engineering and 14th International Conference on Fire and

Explosion Protection, Novi Sad, pp. 46-54

[9] Milovanović, B., Mikulić, D., 2011. ‘’Assessment Method for Combined Heat, Air and

Moisture Transfer in Building Component’’, Energy Management in Cultural Heritage,

Dubrovnik

[10] Künzel, H. M., Holm, H. A., Krus, M., 2008. ‘’Hygrothermal Properties and Behaviour

of Concrete’’, WTA-Almanach, pp. 161-181