Recycled Aggregate Concrete in South East Asia

Performance of Recycled Aggregate Concrete:

Durability

Kevin Paine, BRE Centre for Innovative Construction Materials

Recycled Aggregate Concrete in

South East Asia

About Durability

Photo: Concrete Society

Contents

External attack

Carbonation

Chloride ingress

Aggressive ground

Internal attack

Chlorides and sulfates

Alkali-silica reaction

EXTERNAL ATTACK

The poorer the quality of the aggregate, then

the worse the performance of the concrete.

The poorer the quality of the aggregate, then

the worse the performance of the concrete.

Recycled aggregates are almost always of

poorer quality than natural aggregates.

NATURAL

StandardsNatural

Gravel

Carboniferous

Limestone

Dolomitic

LimestoneGranite Basalt

Flakiness Index BS EN 933-3 12 14 13 14 38

Shape (visual inspection) Rounded Irregular AngularIrregular

AngularAngular

Angular

Flaky

Texture (visual inspection) Smooth Rough RoughCrystalline

RoughRough

Oven dry density, kg/m3 BS EN 1097-6 2570 2680 2620 2610 2730

Loose bulk density, kg/m3 BS EN 1097-3 1520 1440 1430 1450 1460

Compacted bulk density, kg/m3 BS EN 1097-4 1610 1540 1520 1560 1560

Water Absorption, % BS EN 1097-6 1.0 0.8 2.0 0.7 1.5

Los Angeles coefficient, †, % BS EN 1097-2 25 22 25 26 20

micro-Deval value, †, % BS EN 1097-1 20 24 17 12 14

Drying Shrinkage, % BS EN 1374-4 0.03 0.039 0.03 0.016 0.031

Adapted from: Collery, D.J., Paine, K.A. and Dhir, R.K., 2015. Establishing rational use of recycled aggregates in

concrete: a performance-related approach. Magazine of Concrete Research, 67(11), pp.559–574

NATURAL RECYCLED

StandardsNatural

GravelRA-1 RA-2 RA-3 RCA


Shape (visual inspection) Rounded AngularIrregular

AngularAngular Angular

Texture (visual inspection) Smooth Rough Rough Rough Rough










NATURAL RECYCLED

StandardsNatural













Paine, K.A. and Dhir, R.K., 2010. Recycled aggregates in concrete: a performance-related approach. Magazine of Concrete Research, 62(7), pp.519–530

NATURAL RECYCLED

StandardsNatural













Silva R.V., de Brito J. and Dhir, R.K. 2015. Properties and composition of recycled aggregates from construction and demolition waste suitable for concrete productionConstruction and Building Materials 65 (2014) 201–217

NATURAL RECYCLED

StandardsNatural













Ma et al. (2019) Durability Studies on the Recycled Aggregate Concrete in China over the Past Decade: A Review. Advances in Civil Engineering, 4073130, 19pp

External surface

Adapted from: Dhir, R.K. and Paine, K.A., 2007. Performance related

approach to use of recycled aggregates. Report to WRAP

0-30%

50%

100%

RA Content, by

mass of coarse

aggregate

Initial surface absorption


Carbonation

Exposed surface

steel reinforcement

pH >12

CO2 Water

Carbonation

Exposed surface

steel reinforcement

pH >12

CO2 Water

Carbonated layerpH <9

Data points are indicative based on: Ma et al. (2019) Advances in Civil Engineering, Xiao et al. (2013) Journal of Advanced Concrete Technology

11912) 347-359 and Silva, R. V., et al (2015). Cement and Concrete Composites 62, pp.22–32

Natu

ral gra

vel

CCA RA

(where Rb = 100%) Adapted from: Paine, K.A. and Dhir, R.K., 2010. Recycled aggregates in concrete: a performance-related approach. Magazine of Concrete Research, 62(7), pp.519–530

Equal cube strength, 33 MPa

0 to 30% RCA

50% RCA

100% RCA

Higher strength achieved by up to

20 kg/m3 in cement content

Adapted from: Dhir, R K, Limbachiya. M C & Leelawat, T. (1998) Recycled concrete aggregate for use in BS 5328 designated mixes. Report to DETR, CTU/498

Chloride Ingress

Exposed surface

steel reinforcement

Depth

Cl- concentration

Threshold level

Cl- Water

Cover

Data points are indicative only.

For examples of actual data, see: Ma et al. (2019) Advances in Civil Engineering

and Xiao et al. (2013) Journal of Advanced Concrete Technology 11912) 347-359


Data points are indicative only.

For examples of actual data, see: Ma et al. (2019) Advances in Civil Engineering

and Xiao et al. (2013) Journal of Advanced Concrete Technology 11912) 347-359

Practical implications

Tošić, N., Torrenti, J.M., Sedran, T. and Ignjatović, I., 2020. Toward a codified design of recycled aggregate concrete

structures: Background for the new fib Model Code 2020 and Eurocode 2. Structural Concrete, (August), pp.1–23.

steel reinforcement

Suggestions to be conservative

and increase cover by 5 mm

(carbonation) or up to 10 mm

(chloride ingress) when using

recycled aggregates.

CO2 Water Cl-

Performance-

related

approach


Aggressive ground (sulfate ingress)

A much less widely

researched field.

However, in general, the

choice of cement dominates.

(As you would expect).

For example see: Zega, C. J., G. S. Coelho Dos Santos, Y. A. VillagránZaccardi, and A. A. Di Maio. 2016. “Performance of recycled concretes exposed to sulfate soil for 10 years.” Constr. Build. Mater. 102 (Jan): 714–721.

INTERNAL ATTACK

NATURAL

StandardsNatural

Gravel

Carboniferous

Limestone

Dolomitic

LimestoneGranite Basalt

Acid- soluble sulfates % BS EN 1744-1 0.1 ND ND 0.1 ND

Acid- soluble chlorides % BS EN 1744-5 0.01 0.01 0.01 0.00 0.02

Water- soluble chlorides % BS EN 1744-1 0.00 0.00 0.00 0.00 0.00



RECYCLED

Standards RA-1 RA-2 RA-3 RCA

Acid- soluble sulfates % BS EN 1744-1 0.4 0.2 0.3 0.3

Acid- soluble chlorides % BS EN 1744-5 0.1 0.1 0.11 0.1

Water- soluble chlorides % BS EN 1744-1 0.01 0.09 0.01 0.01

WASHING PLANT A B C D E G H I L M

COMPOSITION

Rb, % 1 7 1 1 1 10 0 7 7 3

Rc, % 3 15 9 4 27 13 0 11 5 5

Ru, % 96 74 89 93 68 76 100 75 84 89

Ra, % 0 1 1 2 4 1 0 7 3 3

Rg, % 0 3 0 0 0 0 0 0 1 0

Rc + Ru, % 99 89 98 97 95 89 100 86 89 94

PROPERTIES

Water-soluble chlorides, % 0.01 nd nd nd 0.01 0.01 nd nd 0.03 nd

Water-soluble sulfates, % 0.01 0.21 0.13 0.02 0.08 nd 0.01 0.12 0.34 0.01

Acid-soluble sulfates, % 0.02 0.61 0.48 0.05 0.28 0.62 0.05 0.44 1.48 0.07

Adapted from: Dhir, R K, Paine, K A, Halliday, J E. (2008) Facilitating the wider use of coarse and fine recycled aggregates from washing plants. Report to WRAP, AGG 105-003

Alkali-silica reaction

Aggregates:

Reactive silica

Cement:

Alkalis (K+, Na+)

Expansive gel in hardened concrete

Aggregates:

Reactive silica

Cement:

Alkalis (K+, Na+)

‘Gel’ formed in fresh concrete

MITIGATION

Pozzolanic SCM:

(Reactive Si, [Al])

Recycled aggregates

Unknown rock

(reactive silica?)

Unknown cement

(alkali content?)

Only way to know for sure is to test (Expensive)

Recycled aggregates

(unknown reactivity)

Cement:

Alkalis (K+, Na+)

MITIGATION

Pozzolanic SCM:

(Reactive Si, [Al])

‘Gel’ formed in fresh concrete

Final remarks

Recycled aggregates can be used to make high quality concrete that is

durable and they could potentially be used for all applications of concrete.

However, for some applications there will be necessary additional

considerations (particularly in concrete mix design) that will need to be

accounted for.

About Durability

Photo: Concrete Society

Thank You

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Recycled Aggregate Concrete in South East Asia