Crushed limestone aggregates for concrete and masonry: Results...

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Crushed limestone aggregates for concrete and masonry:

Results from tests according to EN 12620, EN 13043, EN

13242, and EN 13139 standards.

Dimitris Xirouchakis, Alexis Theodoropoulos

Keywords: aggregates, European Standards, construction materials.

ΠΕΡΙΛΗΨΗ: Τα θραυστά ασβεστολιθικά αδρανή αποτελούν την κύρια πηγή αδρανών

για την βιοµηχανία παραγωγής σκυροδέµατος, κονιαµάτων, ασφαλτικών µιγµάτων και

αδρανών οδοποιίας στην Ελλάδα. Ιστορικά, οι δοκιµές ελέγχου των αδρανών και οι

εθνικές προδιαγραφές βασίστηκαν σε διεθνή πρότυπα, π.χ., ASTM International &

AASHTO. Το πλαίσιο ελέγχου και πιστοποίησης της παραγωγής αδρανών στην Ελλάδα

όπως και στην υπόλοιπη ΕΕ έχει αλλάξει µε την ενεργοποίηση των Ευρωπαϊκών

Προτύπων. Στα πλαίσια ελέγχων και πιστοποιήσεων λατοµείων του Ελληνικού χώρου

συνεχίζουµε την συλλογή και αξιολόγηση των γεωµετρικών, φυσικών, χηµικών και

µηχανικών χαρακτηριστικών θραυστών ασβεστολιθικών αδρανών από διάφορα λατοµεία

της ηπειρωτικής και νησιωτικής χώρας εκτός Ιονίων νήσων. Εδώ παρουσιάζουµε τα

αποτελέσµατα των δοκιµών αρχικού τύπου για τον έλεγχο της παραγωγής αδρανών

σκυροδέµατος και κονιαµάτων. Οι δοκιµές αφορούν υλικά µε τις κοινές εµπορικές

ονοµασίες: 1) χαλίκι 2) ψηφίδα / γαρµπίλι και 3) άµµος. Εκτός µερικών (π.χ.,

αλκαλοπυριτική αντίδραση, χηµικοί προσδιορισµοί), οι δοκιµές εκτελέστηκαν σύµφωνα

µε τα πρότυπα που αναφέρονται στα ΕΝ 12620:2002, EN 13043:2002/AC:2004, EN

13242:2002/AC:2004 και EN 13139:2002.

ABSTRACT: Crushed limestone aggregates are the main source of aggregates in the

Greek Construction industry. Historically, testing followed the ASTM International and

AASHTO standard test methods. In light of the changes across EU concerning the

implementation of EN standard test methods as well as the legal and technical framework

for construction products bearing the CE mark, we have been testing, collecting, and

evaluating limestone aggregate testing data from quarries across Greece. Here we present

an initial assessment of a small data set and the correlations observed for coarse and fine

gravel, and sand. All assessed test results were performed following EN standard

procedures referenced in ΕΝ 12620:2002, EN 13043:2002/AC:2004, EN

13242:2002/AC:2004 and EN 13139:2002 except in a few cases, e.g., Alkali-silica

reactivity and chemical analyses.

1Geologist, MSc., PhD, GeoTerra Ltd, Geomechanics & Quality Control Laboratory, 12 Anthrakorichon

Street, 142 35 Nea Ionia, [email protected]

16ο Συνέδριο Σκυροδέματος, ΤΕΕ, ΕΤΕΚ, 21-23/10/ 2009, Πάφος, Κύπρος

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2Mining – Metallurgical Engineer, MSc., A. Theodoropoulos – P. Moskofoglou Partners. – Q4U

Consulting Engineers, 14 Patission Street 14, 106 77 Athens, [email protected]

INTRODUCTION

We present the results from initial type testing of limestone aggregates according to EN

standard methods which are referenced in EN 12640, EN 13043, EN 13242, and EN

13139 standards. Specifically, we have looked at the chemical, physical, and mechanical

properties that are of interest to the construction materials industry. Our goal is to

contribute towards a critically assessed data base of limestone aggregates properties as

established with these methods in light of their widespread usage in Greece, particularly,

and elsewhere in general. We used limestone aggregate samples from quarries located in

the main land and the islands. The samples primarily represent deep and shallow sea

Mesozoic limestones (Eldridge and Fairbridge 1997) with samples from central Greece

and the islands exhibiting variable degrees of re-crystallization. Testing was mainly

performed in two ISO 17025 accredited testing laboratories located in Athens. The results

represent a self-consistent data set whereas data accuracy is secured through the inter-

laboratory testing programs of the respective laboratories.

DISCUSSION

Chemistry

Chemically the samples cover the range from low quality (CaCO3 is 85,0 – 93,5%) to

highly pure limestones (CaCO3 >98,5%) (Table 1 & 2). Preliminary powder XRD data

indicate that they contain calcite (95,7 – 99,5%), dolomite (0,8 – 3,3%), and <1% iron

oxides, iron sulfides, quartz and phyllosilicate minerals. Heavy metals (Table 3) were

either not detected or detected at levels that are typical of marine carbonates globally

(Turekian and Wedepohl, 1961). Alkali-Silica reactivity analyses show that reaction

between alkalis and silica of limestone aggregates and cement in concrete should not be a

problem with the type of aggregates examined here (Table 4); all alkalinity and silica

concentration analyses fall on the field of harmless aggregates (ASTM C 289). However,

we do lack data in Greece to judge the reaction potential for alkalis and carbonate

minerals in concrete. Furthermore, polyaromatic hydrocarbons were not detected and the

radioactive decay measurements of isotopes such Ra – 226, Ra – 228, Th – 228, Th –

232, U – 238 and K – 40 are at innocuous levels (EU Council Directive

96/29/EURATOM 31/5/1996).


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Geometrical, physical, and mechanical properties

Sand sieve analyses (Fig. 1) show that the all grains pass through the 8 mm sieve with

Dmax between 4 and 8 mm, and exhibit a fairly wide range of values in between the 8 mm

and 63 µm sieves. Sand fines content is between 7 and 20%. The crushed limestone sands

examined are devoid of organic substances such as humus and fulvic acid, moreover,

their lightweight contaminants and water soluble components are negligible. The quality

of fines (MB, SE), angularity (Ecs), durability (MS), and water absorption (WA24) behavior

is presented in Table 5 and is deemed more than satisfactory. Mean apparent dry density

values for sand as well as for fine and coarse gravel confirm the mineralogy data as they

are much closer to that of pure calcite (CaCO3) 2,71 g/cm3 and much less to that of

dolomite (CaMg(CO3)2) 2,85 g/cm3 or any of the other carbonate minerals, i.e., siderite

(FeCO3) 3,87 g/cm3, magnesite (MgCO3) 3,0 g/cm

3, ankerite (CaFe(CO3)2) 3,2 g/cm

3.

We take fine gravel to mean aggregates with Dmax equal to 12,5 with a range between

12,5 and 16, mm, and coarse gravel aggregates with Dmax equal to 31,5 (Fig. 1, 3, and 4).

The physical and mechanical properties values of fine and coarse gravel are

unsurprisingly close as it can be seen in Tables 7 and 9 as these properties strongly

depend on mineralogy and rock texture. For the interested reader, we note that ASTM

and EN Los Angeles tests on the same material differ by two units with the ASTM LA

value lower than the EN LA value.

Correlations

Meaningful correlations among physical and mechanical properties of sand arise in a few

cases (Table 6). There is a positive correlation between MB and Ecs values that may

suggest that clay-size material or clays may inhibit flow of sand grains. The correlation

between ρα and Ecs was anticipated since the Ecs calculation is based on density. A close

relationship between MB and SE did not materialize in these types of aggregates as they

are generally devoid of clay-size or clay materials. However, if we include in the data set

MB and SE values from all-in aggregates which are used in road pavement construction

then the correlation becomes stronger as the data cover a greater range of values (Fig. 2).

For fine and coarse gravel, significant (i.e. correlation coefficient >|0,5|) and common in

both aggregate types correlations are observed between the following pairs of tests: MS

and VLA, MDE and LA, FI and SI (Table 7 and 9). The correlation between MS and VLA is

surprising and needs further investigation as we have not seen it in the literature.

Nonetheless, the strong relationships between these three pairs of tests suggest that it may

be advantageous to use them as discriminating constraints of aggregate quality (Fig. 5, 6,


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and 7); aggregates falling within the lower right quadrangle should have a better overall

behavior overtime. We do not find for limestone aggregates a statistically significant

relationship between either water absorption or silica content and wet Micro-Deval test

results as seen in Brennan et al. (2003) for igneous aggregates. In contrast, the data agree

with the Pétursson’s conclusions (2000) regarding the strong correlation between FI and

SI values in Icelandic, presumably, basaltic aggregates.

REFERENCES

ASTM C289, “Standard Test Method for Potential Alkali-Silica Reactivity of Aggregates

(Chemical Method)”, ASTM International, West Conshohocken, PA, (2007).

Brennan, M.J., Crawley, K., Sheahan, J.N., and Jordan, J., “Ranking the performance of

aggregates using CEN test results”, Road Materials and Pavement Design, Vol. 4, No4,

439 – 454, (2003).

Moores, E.M., Fairbridge, R.W., “Encyclopedia of European and Asian regional

geology”, Springer, (1997).

European Aggregates Association Annual Report,

http://www.uepg.eu/uploads/documents/pub-15_en-uepg_-_ar2007_en.pdf, (2007)

EN 12620, “Aggregates for concrete”, (2008).

EN 13043, “Aggregates for bituminous mixtures and surface treatments for roads,

airfields and other trafficked areas”, (2002).

EN 13139, “Aggregates for mortar”, (2002).

EN 13242, “Aggregates for unbound and hydraulically bound materials for use in civil

engineering work and road construction”, (2008).

Harrison, D.J., “Industrial Minerals: Limestone”, British Geological Survey Technical

Report WG/92/29, (1993).

Lorenz, W. and Gwosdz, W., “Manual of the Geotechnical Assessment of Mineral

Construction Material”, Geologisches Jahrbuch Sonderhefte, Reihe H, Heft SH 15,

Hannover, (2003).

Pétursson Pétur, “Testing of the aggregate bank with two CEN methods, MDE and FI”,

Public Roads Administration, Report E-38, Reykjavic, (2000).


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Turekian, K.K. and Wedepohl, K.H., “Distribution of the Elements in some major units

of the Earth's crust”, Geological Society of America, Bulletin 72: 175-192, (1961).

US Geological Survey Minerals Yearbook, http://minerals.usgs.gov/minerals/pubs,

(2007).


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Table 1. Bulk chemistry data

Parameter Unit n µ s min max

SO4 -2 (water-soluble) wt%

2 nd

Cl- wt%

5 0,001 0,001 0,000 0,002

SO3 -2 (acid-soluble) wt%

2 nd

PbO wt% 7 0,001 0,000 0,001 0,001

ZnO wt% 11 0,001 0,002 0,000 0,010

P2O5 wt% 11 0,073 0,112 0,030 0,295

FeO wt% 5 nd

Fe2O3 wt% 16 0,074 0,056 0,01 0,28

Na2O wt% 16 0,040 0,005 0,03 0,05

K2O wt% 15 0,008 0,006 0,00 0,02

SiO2 wt% 16 1,220 0,792 0,22 6,03

Al2O3 wt% 16 0,080 0,064 0,02 0,19

MgO wt% 16 0,657 0,633 0,15 2,66

CaO wt% 16 54,0 1,4 50,9 55,4

CO2 wt% 16 42,9 0,9 40,5 43,6

H2O wt% 16 0,12 0,03 0,07 0,19

Moisture wt% 16 0,75 1,60 0,07 5,31

Sum 99,9 99,2 100,9

Table 2. Carbonate and equivalent sodium content


Loss on ignition % 16 43,2 1,2 41,4 46,9

CaCO3 % 16 96,1 2,3 90,8 99,0

CaO in CaCO3 % 16 99,7 1,4 95,4 100,1

Να2Οeq % 16 0,05 0,01 0,03 0,06

Symbols: (n) number of measurements, (µ) average, (s) standard deviation, (min)

minimum value, (max) maximum value, (nd) not detected.


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Table 3. Heavy metals concentration


Co mg/kg 16 0,4 1,2 nd 3,8

Ni mg/kg 14 9,1 13,3 nd 33,5

Cr mg/kg 14 8,4 5,6 nd 22,0

Cd mg/kg 14 0,0 0,2 nd 0,6

Pb mg/kg 14 1,1 2,3 nd 5,8

Sb mg/kg 14 0,1 0,2 nd 0,8

As mg/kg 14 0,4 0,4 nd 1,1

Hg mg/kg 14 0,0 0,0 nd nd

Table 4. Alkali-Silica reactivity data

Parameter unit n µ s min max

Sc mmol/l 16 19,0 41,7 0,3 132,0

Rc mmol/l 16 956,4 31,2 16,0 1040,0

Silica concentration (Sc). Alkalinity (Rc).

Figure 1. Range (solid lines) and mean (heavy solid line) of sand sieve analyses.


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Table 5. Sand physical and mechanical characteristics

Parameter

Unit n µ s min max

Methylene blue MB g/kg 18 0,5 0,3 0,2 1,2

Sand equivalent SE % 18 69 6 52 81

Flow coefficient Ecs sec 17 21 8 14 38

Apparent dry density ρα Mg/m3

18 2,697 0,054 2,522 2,743

Water absorption (24 h) WA24 % 18 0,9 0,1 0,5 1,1

Mg2SO4 test MS % 17 3,4 2,1 0,2 7,4

Lightweight contaminators LPC % 16 0,210 0,524 0,000 1,990

Water-soluble constituents WS % 15 0,084 0,154 0,000 0,570

Dry bulk density (loose) ρb Mg/m3

18 1,603 0,101 1,372 1,754

Table 6. Correlation coefficient matrix for sand properties

MB SE Ecs ρα WA24 MS LPC WS ρb

MB 1,00

SE -0,23 1,00

Ecs 0,86 -0,10 1,00

ρα -0,61 0,19 -0,78 1,00

WA24 -0,07 -0,27 0,15 -0,21 1,00

MS 0,40 -0,24 0,39 -0,25 0,20 1,00

LPC 0,34 0,06 0,49 -0,36 -0,23 0,03 1,00

WS -0,13 -0,23 -0,16 0,12 -0,42 0,33 -0,11 1,00

ρb -0,01 0,08 0,28 -0,36 0,28 0,20 -0,30 0,32 1,00


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Figure 2. Sand Equivalent (SE) and Methylene Blue (MB) relationship among sand from

crushed limestone aggregates for use in concrete and road base construction. The heavy

solid line is a simple linear fit to the data with solid lines on either side marking the 95%

confidence limits of the prediction ability of the equation for this type of aggregates only.

Figure 3. Range (solid lines) and mean (heavy solid line) of fine gravel sieve analyses.


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Table 7. Fine gravel physical and mechanical properties

Parameter

unit n µ s min max

Apparent dry density

ρα Mg/m3 18 2,704 0,022 2,643 2,746


Mg2SO4 test MS % 17 2,9 2,0 0,4 7,4

Resistance to fragmentation LA % 18 28,3 4,4 21,0 42,0

Resistance to wear (wet) MDE % 18 17,5 6,9 8,5 32,6

Shape Index SI % 17 13,5 7,8 5,1 29,5

Flakiness Index FI % 18 14,6 5,8 7,7 24,2

Resistance to thermal shock VLA

16 2,3 1,4 1,0 4,6

Dry bulk density (loose) ρb Mg/m3 18 1,393 0,056 1,328 1,505

Table 8. Correlation coefficient matrix for fine gravel properties

ρα WA24 MS LA MDE SI FI VLA ρb

ρα 1,00

WA24 0,37 1,00

MS -0,14 -0,13 1,00

LA -0,22 -0,13 0,06 1,00

MDE 0,16 -0,17 -0,03 0,59 1,00

SI -0,01 -0,20 -0,43 0,18 0,19 1,00

FI 0,23 0,12 -0,15 0,08 -0,10 0,62 1,00

VLA 0,00 0,07 0,95 -0,18 -0,16 -0,55 -0,12 1,00

ρb -0,42 0,64 0,64 0,23 -0,26 -0,53 -0,11 0,52 1,00


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Figure 4. Range (solid lines) and mean (heavy solid line) of coarse gravel sieve analyses.

Table 9. Coarse gravel physical and mechanical properties

Parameter

unit n µ s min max

Apparent dry density

ρα Mg/m3 18 2,698 0,025 2,611 2,727


Mg2SO4 test MS % 17 2,8 2,2 0,1 7,4

Resistance to fragmentation LA % 18 28,6 5,3 17,0 42,0

Resistance to wear (wet) MDE % 18 18,9 7,3 9,9 32,6

Shape Index SI % 16 13,4 5,7 6,0 22,2

Flakiness Index FI % 18 12,1 4,8 4,8 23,6

Resistance to thermal shock VLA 15 1,9 1,4 0,2 4,6

Dry bulk density (loose) ρb Mg/m3 18 1,378 0,050 1,281 1,466


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Table 10. Correlation coefficient matrix for coarse gravel properties

ρα WA24 MS LA MDE SI FI VLA ρb

ρα 1,00

WA24 -0,21 1,00

MS -0,31 0,04 1,00

LA 0,02 0,37 0,27 1,00

MDE 0,22 0,17 0,07 0,56 1,00

SI 0,54 -0,44 -0,24 0,15 0,36 1,00

FI -0,03 -0,30 0,14 0,10 0,09 0,65 1,00

VLA -0,11 -0,30 0,76 -0,12 -0,34 -0,26 0,25 1,00

ρb -0,33 -0,20 0,47 0,13 -0,16 -0,32 -0,15 0,53 1,00

Figure 5. Resistance to fragmentation vs. Resistance to wear values. Heavy solid lines

represent the respective means.


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Figure 6. Flakiness index vs. Shape index. Heavy solid lines represent the respective

means.

Figure 7. Magnesium sulfate vs. Thermal Shock Resistance values. Heavy solid lines

represent the respective means.


Crushed limestone aggregates for concrete and masonry: Results...

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