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Evaluating the durability of two
recycled aggregates to be used in
basal drainage layer of landflills
Gonçalo Rodrigues (1, 2)
António José Roque (1)
Ana Paula da Silva (2)
(1) LNEC (2) FCTUNL
WASCON 2012, May 30 – June 1
SUMMARY
1. Introduction
2. Studied materials
3. Experimental program
4. Results and discussion
5. Conclusions
2
INTRODUCTION
Durabilty study of two recycled aggregates:
o Inert Siderurgical Aggregate for Construction (ISAC), processed from
electric arc furnace steel slag,
o Crushed concrete aggregate reclaimed from construction and demolition
waste (CCCDW).
Comparing to durability of two natural aggregates (reference material):
o Basalt (BA),
o Limestone (LIM).
Evaluating the technical feasibility of using recycled aggregates in the
construction of leachate collection and removal layer of basal
containment system of landfills.
Contribute to a Organized Market of Waste, a sustainable construction
and a reduction in natural aggregates exploitation.
WASCON 2012, May 30 – June 1 3
STUDIED MATERIALS
recycled aggregates
Electric arc furnace steel
slag (phase processing)
Inert Siderurgical Aggregate
for Construction (ISAC)
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Construction and demolition
waste (phase processing)
Crushed concrete aggregate
(CCCDW)
STUDIED MATERIALS
recycled aggregates
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WASCON 2012, May 30 – June 1
Basalt quarry
(exploitation front)
Basalt aggregate (BAS) Crushed basalt
(phase processing)
STUDIED MATERIALS
natural aggregates
6
WASCON 2012, May 30 – June 1
Limestone quarry
(exploitation front)
Limestone aggregate (LIM) Crushing of the limestone
(phase processing)
STUDIED MATERIALS
natural aggregates
7
RSU Leachate collection Pumping RSU leachate in a well
STUDIED MATERIALS
RSU leachate
WASCON 2012, May 30 – June 1 8
STUDIED MATERIALS
Location of studied materials WASCON 2012, May 30 – June 1 9
EXPERIMENTAL PROGRAM
Petrographic
analysis
Macropetrographie
Micropetrographie
Physical
characterization
Density
Effective porosity
Water absorption
Durability
evaluation
Slake durability test with water and leachate
o without previous immersion
o with previous immersion (during 15 days)
Before and after slake durability test (SDT)
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11 WASCON 2012, May 30 – June 1
RESULTS AND DISCUSSION
petrographic analysis (before SDT) ISAC
Macropetrographie
Dense material, vesicular texture, dark in
color and rough surface.
Minerals are not observable to the naked eye
Presence of small iron particles.
Micropetrographie
Material of vesicular and aphanitic texture,
and fine-grained particles.
Matrix composed of opaque minerals
(especially iron oxides) and unidentifiable
mineral species.
12 WASCON 2012, May 30 – June 1
RESULTS AND DISCUSSION
petrographic analysis (before SDT) CCCDW
Macropetrographie
Multiphase material, heterogeneous, non-
friable.
Cementitious matrix color gray and porous.
Crushed coarse and fine aggregates.
Micropetrographie
Material of complex structure composed of
three phases: cementitious matrix, transition
zone and crushed aggregates.
Fine aggregates corresponding to quartz
sand.
13 WASCON 2012, May 30 – June 1
RESULTS AND DISCUSSION
petrographic analysis (before SDT) BAS
Macropetrographie
Magmatic, compact, and melanocrata rock.
Aphanitic texture, very slightly porous.
There are no signs of alteration.
Micropetrographie
Porphyritic texture, fine-grained particles, and
composed by two stage of crystallization:
aphanitic matrix (90%) with phenocrystals of
olivine (10%).
Matrix is composed by plagioclases, opaque
minerals, olivine and pyroxene.
14 WASCON 2012, May 30 – June 1
RESULTS AND DISCUSSION
petrographic analysis (before SDT) LIM
Macropetrographie
Sedimentary, carbonate and oolitic rock.
Presence of spherical nodules and veins of
calcite.
Micropetrographie
Matrix is composed by minerals of calcite and
some cemented elements (clasts and
oolites).
There are no signs of alteration in calcite.
15 WASCON 2012, May 30 – June 1
RESULTS AND DISCUSSION
physical characteristics (before SDT)
Specimen Bulk density
b (Mg/m3)
Real density
r (Mg/m3)
Ef. porosity
Pe (%)
W. absorption
wmax (%)
ISAC 3.77 3.28 12.40 3.83
CCCDW 2.58 2.14 16.88 7.89
BAS 3.02 3.00 0.45 0.14
LIM 2.72 2.58 5.40 2.20
ISAC is denser than CCCDW.
Effective porosity of the ISAC is identical to CCCDW.
Effective porosity of the ISAC (12.40%) is influenced by the
processing of steel slag.
ISAC is denser than BAS and LIM and with Pe and wmax also higher.
CCCDW is less dense than BAS and LIM and with Pe and wmax higher.
16 WASCON 2012, May 30 – June 1
0
10
20
30
40
50
60
70
80
90
100
Mate
rial re
tain
ed
(%
)
Id1
Id2
Id5
RESULTS AND DISCUSSION
durability
W L
ISAC
W W W L L L WI WI WI WI LI LI LI LI
CCCDW BAS LIM
• Very low durability
• Very high durability
• Low durability
• High durability
•Medium high
durability
• Medium durability
Durability index is greater than 95.0% in all specimens
Recycled and natural aggregates are classified as very high durability.
Gamble
classification
17 WASCON 2012, May 30 – June 1
RESULTS AND DISCUSSION
petrographic analysis (after SDT) ISAC
Macropetrographie
Deposition of organic matter of the leachate on the surface of the
specimens, in particular in the alveolus.
Oxidized iron particles.
initial specimen specimen after SDT
(ISAC_SDTI_L)
WASCON 2012, May 30 – June 1
RESULTS AND DISCUSSION
petrographic analysis (after SDT) ISAC
Micropetrographie
Higher concentrations of opaque minerals, especially iron oxides.
initial specimen specimen after SDT
(ISAC_SDTI_L)
18
WASCON 2012, May 30 – June 1
RESULTS AND DISCUSSION
petrographic analysis (after SDT) CCCDW
Macropetrographie
Alterations in the color of the cementitious matrix as a result of
deposition of organic matter of the leachate on the surface of the
specimens.
initial specimen specimen after SDT
(CCCDW_SDTI_L)
19
WASCON 2012, May 30 – June 1
RESULTS AND DISCUSSION
petrographic analysis (after SDT) CCCDW
Micropetrographie
There are no signs of alteration.
initial specimen specimen after SDT
(CCCDW_SDTI_L)
20
WASCON 2012, May 30 – June 1
RESULTS AND DISCUSSION
petrographic analysis (after SDT) BAS
Macropetrographie
Slight alterations in color of the basalt as a result of deposition of
organic matter of the leachate on the surface of the specimens.
initial specimen specimen after SDT
(BAS_SDTI_L)
21
WASCON 2012, May 30 – June 1
RESULTS AND DISCUSSION
petrographic analysis (after SDT) BAS
Micropetrographie
Partial or total alteration of phenocrystals of olivine (alteration of the
color and partial loss of mass of the phenocrystals).
initial specimen specimen after SDT
(LIM_SDTI_L)
22
WASCON 2012, May 30 – June 1
RESULTS AND DISCUSSION
petrographic analysis (after SDT) LIM
Macropetrographie
Alterations in color of the limestone as a result of deposition of
organic matter of the leachate on the surface of the specimens.
initial specimen specimen after SDT
(BAS_SDTI_L)
23
WASCON 2012, May 30 – June 1
RESULTS AND DISCUSSION
petrographic analysis (after SDT) LIM
Micropetrographie
There are no signs of alteration.
initial specimen specimen after SDT
(LIM_SDTI_L)
24
25 WASCON 2012, May 30 – June 1
RESULTS AND DISCUSSION
physical characteristics (after SDT)
Specimen b (Mg/m3) r (Mg/m3) Pe (%) wmax (%)
ISAC_SDT_W 3.98 3.58 10.00 2.88
ISAC_SDT_L 3.71 3.28 11.65 3.77
ISAC_SDTI_W 3.77 3.28 12.32 3.77
ISAC_SDTI_L 3.78 3.29 12.61 3.90
CCCDW_SDT_W 2.62 2.22 15.34 6.93
CCCDW_SDT_L 2.63 2.27 13.59 5.99
CCCDW_SDTI_W 2.65 2.24 15.27 6.82
CCCDW_SDTI_L 2.62 2.27 13.59 6.00
BAS_SDT_W 3.01 2.99 0.48 0.16
BAS_SDT_L 3.01 3.00 0.38 0.13
BAS_SDTI_W 3.04 3.02 0.45 0.15
BAS_SDTI_L 3.00 2.99 0.41 0.14
LIM_SDT_W 2.74 2.57 6.15 2.41
LIM_SDTI_L 2.72 2.57 5.33 2.09
LIM_SDT_W 2.72 2.59 4.70 1.82
LIM_SDTI_L 2.72 2.56 5.99 2.38
3.7
7
3.2
8
12.4
0
3.8
3
2.5
8
2.1
4
16.8
8
7.8
9
3.0
2
3.0
0
0.4
5
0.1
4
2.7
2
2.5
8
5.4
0
2.2
0
No significant quantitative changes have occurred on physical
characteristics of the specimens after SDT tests.
The use of water and leachate had no significant influence on physical
characteristics of the specimens.
The exception was observed for the porosity accessible to water (Pe)
and water absorption under vacuum conditions in CCCDW_SDT_L and
CCCDW_SDTI_L specimens. Pe and wmax decreased of about 3.3% and
2.0%, respectively, relating to these properties in CCCDW specimen.
These differences most likely have resulted from the deposition of
organic matter of the leachate on surface of the specimens,
particularly in the pores accessible to water.
RESULTS AND DISCUSSION
physical characteristics
CCCDW specimen
(before SDT)
CCCDW_SDTI_L specimen
(after SDT)
WASCON 2012, May 30 – June 1 26
WASCON 2012, May 30 – June 1
CONCLUSIONS
According to Gamble classification, either the recycled aggregates (ISAC and CCCDW), or the natural aggregates (BAS and LIM), belong to the category of materials of very high durability, even when subjected to mechanical and chemical conditions more aggressive than those provided in the SDT test proposed by ISRM.
Previous immersion of specimens in tap water and in the acidified RSU leachate for 15 days and carrying out three slake-durability cycles did not affect the durability of the materials studied, except, though insignificant, in the case of CCCDW_SDTI_L specimen.
The results of petrographic study (macro- and microscopic) and physical characterization are consistent with the classification achieved for the four types of aggregates, recycled and natural, since no significant changes occurred in their initial petrography and physical properties.
The results obtained with the recycled aggregates, CCCDW and ISAC, as well as the natural ones, BAS and LIM, have showed their technical feasibility to be used in the proposed application, as well as in the most of the transportation infrastructure and geotechnical works, from the point of view of durability.
27
ACKNOWLEDGEMENTS
The authors would like to thank to:
Demotri Company (Ambigroup Group), for providing crushed
concrete aggregate;
Iron and Steel Company, for providing Inert Siderurgical
Aggregate for Construction;
Alves Ribeiro Company, for providing basalt aggregates;
Agrepor Company, for providing limestone aggregates;
Amarsul Company (AdP Group), from providing RSU leachate.
WASCON 2012, May 30 – June 1 28
THANK
YOU ALL!
WASCON 2012, May 30 – June 1 29