and restricting the amount of fines produced- and by the Dutch test NEN ... weight of the sample, rounded to the nearest whole number, is reported as the AIV.
C O R R E L A T I O N STUDY OF A G G R E G A T E S T R E N G T H TESTS
L.R.S.Kissakwai and P.N.W.Verhoef-'^ ^ ITC, Institute for Aerial Photography and Remote Sensing, Engineering Geology Section, Delft, The Netherlands; present address: P.O.Box 567, Dar-Es-Salaam, Tanzania ^ Delft University of Technology, Faculty of Mining and Petroleum Engineering, Section of Engineering Geology, P.O.Box 5028, 2600 G A Delft, The Netherlands ^ To whom correspondence should be sent
ABSTRACT On a suite of eleven aggregate samples seven aggregate strength testing procedures have been carried out. The tests have been performed according to prescribed standards and include the Aggregate Crushing Value (ACV; BS 812), Ten Per Cent Fines Value (BS 812), Aggregate Impact Value ( A I V ; BS 812), Modified Aggregate Impact Value Test ( M A I V ; Hosking and Tubey, 1969), Dynamic Crushing Value ( N E N 5185, Dutch modified version of A I V ) , Impact Crushing Value (TP Min-StB, Teil 5.1, German impact test for road aggregate), Los Angeles Abrasion test ( L A A ; A S T M C131). The aggregates have been selected to represent a range of weak to strong materials. Alternative materials such as crushed concrete and masonry bricks have been included. The aggregates have been characterised using petrographic description and their Flakiness Index, Dry Density and Water Absorption (BS 812) and Methylene Blue Adsorption value ( M B A , Stapel and Verhoef, 1989) were determined. The tests have been performed to obtain relationships between the different tests and to compare the procedures of the aggregate impact tests. Simple regression analysis has been carried out, including non-hnear equations. Those relations which seemed logical and had a high correlation factor are given in the accompanying table 2. With respect to the development of new European standards for aggregates this study indicates that the aggregate impact test ( A I V ) appears useful for general use. The A I V , furthermore, may adequately predict the value of the other aggregate tests studied. The A I V equipment can be easily transported and the test is both easy to perform and cheap. However, the modifications proposed by Hosking and Tubey (1969) -using wet aggregate and restricting the amount of fines produced- and by the Dutch test N E N 5185 -sieving with slotted sieves to obtain a uniform cuboidal shape- could improve its usefulness.
Proceedings o f t h e 2nd International Conference on Aggregates, Erlangen, Germany (to be pubhshed July 1991) ( | 4 t n ^ >> i J
SAMPLE D E S C R I P T I O N
M G : crushed building masonry. Consists of fragments of bricks, mortar, concrete, glass, wood etc. Before testing the sample was thoroughly mixed and wood fragments were removed. K L : crushed road masonry. Consists of crushed road pavement bricks. BG: crushed concrete from demohshed concrete works. L I : limestone from Nothingham (UK), road aggregate. Light grey coarse grained fossilrich boundstone, locally recrystallised with local stylolites. L I I : dark grey, layered fossil-rich limestone from Doornik, Belgium, mm-cm size fossils occur in fine grained matrix. Locally coarsely recrystaUised fine to medium grained with locally isolated 0.02 mm size quartz grains. Healed, calcite cemented, cracks occur. St: crushed river gravel from Roermond (Netherlands). Fragments of gravel derived from quartzites, quartzitic sandstones, quartz and flint. Ga: Gabbro from Krager0 (Norway). Medium to fine grained dark green metamorphic gabbro (amphibolite), consisting of amphibole, plagioclase, pyroxene, biotite, serpentine and minor opaque oxide minerals. Gr: Granite from the east coast of Scotland. Coarse grained (2-3 mm), pink coloured, biotite granite. Feldspars are mainly fresh, some alteration to chlorite and kaolinite is locally present. Bit: Basanite from Wassenach (Eifel, Germany). Dense lava, consisting for 30-40 vol.% of mm-size phenocrysts of augite, phlogopite (3%) and opaque oxides, embedded in a fine-grained matrix consisting of augite and plagioclase. Bit: Basalt from Mayen (Eifel, Germany). Dense lava, consisting of mm-size phenocrysts of augite, phlogopite and iron(hydr)oxides, embedded in a groundmass (about 70 vol.%) of plagioclase, augite and opaque minerals. Vo: Tuffaceous lava. Highly porous brown coloured aggregate from the Eifel area (Germany), mm-sized phenocrysts of augite, hauyn, plagioclase and opaque minerals occur in a groundmass of augite, plagioclase and opaque minerals.
TESTS P E R F O R M E D
Aggregate Crushing Value (ACV) test (BS 812, Part 3: 1975) The A C V test gives a relative measure of the resistance of an aggregate to crushing under a gradually applied compressive load. About 2 kg of surface dry standard aggregate sample in the size range of 14 to 10 mm, compacted in a prescribed way in a 150 m m diameter steel cylinder, is subjected to a load transmitted at a constant rate through a piston in a compression test machine until a total load of 400 k N is achieved in 10 minutes. The crushed sample is then sieved on sieve size 2.40 mm, and the fraction passing the sieve is calculated as the percentage of the initial sample weight. The average of two tests, rounded off towards the nearest whole number, is reported as the A C V . A low A C V indicates a rock resistant to crushing.
Ten Percent Fines Load (BS 812, Part 3: 1975) This test is a modification of the A C V test. When values of A C V exceed 30%, the sensitivity of the A C V test is impaired by the filling of pore spaces between particles with crushed fine material, produced in the course of the test. The 10% fines test was designed to overcome this problem. The Ten Percent Fines value represents the load required to produce 10% fines. The test is performed with the same apparatus as the A C V test, but with a maximum load which produces a percentage of fines between 7.5 and 12.5%. Two determinations are required and the load which gives 10% fines is calculated and reported.
Aggregate Impact Value (AIV) test (BS 812, Part 3: 1975) A surface dry standard size (14 - 10 mm) aggregate sample is placed in a cylindrical cup of prescribed dimensions and compacted. The sample is subjected to 15 blows of a hammer (13.5 - 15 kg, diameter 100 mm) falling freely over a height of 380 mm, while the time interval between the blows is maintained to be at least 1 second. After 15 impact blows the sample is sieved on a BS 2.40 mm sieve and the fraction passing is determined. The average of two determinations, expressed as the ratio of the initial weight of the sample, rounded to the nearest whole number, is reported as the A I V .
Modified Aggregate Impact Value (MAIV) test (Hosking and Tubey, 1969) As in the A C V test, when values of A I V exceed 26%, the sensitivity of the test is impaired due to the filling of pore spaces between particles with crushed fines. The procedure is similar to that of the A I V test, but the number of hammer blows is limited to obtain a yield of between 5 to 20 % fines. The sample is saturated first and tested while surface dry. After testing the sample is oven dried for 12 hours at 100 - 110 °C before sieving. The M A I V is obtained by multiplying the percentage finer than 2.40 mm by 15/x, where x is the number of hammer blows applied.
Dynamic Crushing Value (Dutch AIV) test (NEN 5185, draft 1988) The Dutch version of the A I V test uses the British Standard apparatus and a similar procedure, except that a different sample size is chosen (11.2 - 8 mm). Furthermore, the shape of the aggregate particles is controlled by use of slotted sieves S8 and S5.6 with slot widths of 8 and 5.6 mm and slot lengths of 40 and 30 mm respectively. The sample is sieved on the slotted sieves and the fraction passing S8 and retained on S5.6 is used for the test. The resulting aggregate particles have a cuboidal shape. After the test the fraction of fines passing the 2.0 mm sieve is expressed as the percentage of the total weight of the sample. The average of two test results, rounded to the nearest whole number, is given as the Dynamic Crushing Value (dynamische verbrijzelingswaarde).
Aggregate Impact Crushing Value (German AIV) test (TPMin-StB-Teil 5.2.1.4,1982) and German Shape Factor (Idem, Teil 6.1.1.2) The German aggregate impact test is of different design and procedure. The aggregate sample consists of a mkture of 3 fractions; 50 weight% 8/10 mm, 25 weight% 10/11.2 mm and 25 weight% 11.2/12 mm. About 1 to 1.5 kg of this mixture is placed in a mould on which a stamp exerts a load of 1 k N . The sample is subjected to 10 blows of a 50 kg hammer, falling freely from a height of 370 mm. After the blows, the sample is sieved on a set of sieves, allowing the fraction retained on 8, 5, 2, 0.63, 0.2 and passing 0.2 mm to be weighed. The weight percentage passing of the sieves is calculated summed and divided by 5 to give the average percentage passing, which is the Impact Crushing Value (Schlagzertrümmerungswert, SZ8/i2)- The average of three determinations is reported, rounded to 0.1. For this test the shape factor of the sample has to be reported, as the weight percentage of particles with a length/width ratio > 3. A special calliper is used for its determination and about 300 particles have to be measured.
Flakiness Index (BS 812, section 105.1: 1985) Particles are classified as flaky when they have a thickness less than 0.6 of their nominal size (mean of the limiting sieve sizes of the size fraction in which the particle occurs). Flaky particles are known to influence the results of A C V and A I V tests. The Flakiness Index is found by separating the flaky particles and expressing their mass as a percentage of the mass of the sample tested. Not less than 200 particles should be passed through a special designed slotted gauge. For this study the flakiness index was determined for the aggregate size fraction 14/10mm.
Los Angeles Abrasion Test (LAA; ASTM C131-81) For this study a grading of 2.5 kg 19/13.2 mm plus 2.5 kg 13.2/9.5 mm was used. The aggregate sample was placed with 11 steel balls (each 4585 g) in the steel drum (diameter 711 mm). The drum rotates, a shelf plate picks up the sample and the balls, carrying them around until they are dropped on the opposite site of the drum, creating an impact crushing effect. The contents then roll with the drum, creating an abrading and grinding action until they are dropped on the opposite site again. The drum rotates with 30 revolutions per minute. After 100 revolutions the sample is discharged f r o m the drum and sieved on a 1.7 mm sieve. The weight of the sample retained on the sieve, W^oo, is recorded after which the whole sample is replaced in the drum and rotated for another 400 revolutions. Similarly the retained weight W500 is determined. A uniformity factor and the L A A value are calculated as foUows: t^^=(^0-^100)/(^0-^500)
Z^=100*(W^o-^50o)/^o %
Dry Density and Water Adsorption (BS 812) The volume of about 100 g of aggregate sample was determined by weighing the water saturated submerged mass and the dry mass, f r o m which also the dry density ( M d r y / V ) and Water Adsorption ( W A = 100*(Msat-Mdry)/Mdry % ) were calculated. For the porous lava aggregate samples the volume was determined by the water displacement method, after submerging the sample in heavy oil or melted wax to blind the pores.
Methylene Blue Adsorption Test (Stapel and Verhoef, 1989) This test was used to determine the presence of swelling clay minerals or other water adsorbing substances in the aggregates. A representative portion of the aggregate was ground to a size smaller than 0.15 mm. A suspension of 2 g of the rock powder was titrated with a methylene blue solution. Using the spot method the amount of methylene blue adsorbed was determined and expressed in g methylene blue per 100 g sample. When the M B A value exceeds 0.7 g/ lOOg swelling clays are hkely to be present and the aggregate is considered marginally sound. Above a value of 1 g/lOOg the aggregate is regarded unsound. Two determinations per sample were done.
T E S T CONDITIONS Before testing the aggregates were crushed, if necessary, to obtain the required size gradation and thoroughly mixed to homogenise the samples. The aggregates were tested in their "as received" moisture condition, but for the M A I V and the Dutch A I V test. For the Modified A I V test the samples were saturated for 24 hours under vacuum and tested while surface dry. For the Dutch A I V test the samples were oven dried for 24 hours at
105 °C and tested after cooling to room temperature. REGRESSION ANALYSIS The following relations were used for regression analysis of the data: Y=a+bX
Y-aX''
l/Y-a+bX
Y-a+blnX
REFERENCES A M E R I C A N SOCIETY FOR TESTING M A T E R I A L S . 1982. Resistence to degradation of small-size coarse aggregate by abrasion and impact i n the Los Angeles machine. A S T M designation C131 - 81. Annual book of A S T M Standards, Part 14, Concrete and Mineral Aggregates, pp 91 - 94. A M E R I C A N SOCIETY FOR TESTING M A T E R L \ L S . 1982. Resistence to degradation of large-size coarse aggregate by abrasion and impact in the Los Angeles machine. A S T M designation C535 - 81. Aimual book of A S T M Standards, Part 14, Concrete and Mineral Aggregates, pp 348 - 349. BRITISH STANDARDS INSTITUTION. 1972. Methods for Testing aggregates, Part 3. Methods for determination of mechanical properties. BS812 : Part 3 : 1975. COLLIS, L and FOX, R.A. (editors). 1985. Aggregates: Sand, gravel and crushed rock aggregates for constmction purposes. Engineering Geology Special Pubhcation No. 1, The Geological Society. London. FORSCHUNGSGESELLSCHAFT F Ü R STRASSEN- U N D V E R K E H R S W E S E N ( G E R M A N Y ) . 1982. Schlagprüfung an Splitt 8/12". Technische Prüfvorschriften für Mineralstoffe i m Strassenbau, TPMin-StB, Teil 5.2.1.4. FORSCHUNGSGESELLSCHAFT F Ü R STRASSEN- U N D V E R K E H R S W E S E N ( G E R M A N Y ) . 1982. Kornform mit der Kornform-Schieblehre. Technische Prüfvorschriften für Mineralstoffe i m Strassenbau, TPMin-StB, Teil 6.1.1.2. HOSKING, J.R. and T U B E Y , L.W. 1969. Research on low grade and unsound aggregates. RRI Report L R 293. Road Research Laboratory, Ministry of Transport, Crowthorne, U K . N E D E R L A N D S N O R M A L I S A T I E INSTITUUT. 1988. Breuksteen en vergelijkbare steenmaterialen - Bepaling van de dynamische verbrijzehngswaarde. (draft; januari 1988). Ontwerp N E N 5185. Delft, Netherlands. STAPEL, E.E. and V E R H O E F , P. 1989. The use of the methylene blue adsorption test in assessing the quality of basaltic tuff rock aggregate. Engineering Geology, 26, pp 233 246. T U R K , N . and D E A R M A N , W.R. 1989. A n investigation of the relation between Ten percent Fines Load and Crushing Value Tests of aggregates. Bull. I.A.E.G., 39, pp 145 154.
Test Sample
AC V (%)
Ten % fines (kN)
AI V (%)
MAI V (%)
Dutch AIV (%)
Germa n AIV (%)
LAA (%)
Dry Density (Mg/m3)
W A (%)
MB A (%)
Flakin. Index (%)
German Shape Factor (%)
M G crushed building masonry
36
60
40
60
41
39.0
53.8
1.92
10.1
0.15
16
12.0
K L crushed road masonry
24
160
24
24
25
27.7
25.9
2.10
6.4
0.15
24
10.0
B G crushed concrete
24
110
26
30
29
28.1
30.9
2.32
6.3
0.15
10
1.6
L I Limestone
21
160
21
17
19
23.3
24.5
2.61
0.6
0.15
5
4.4
G a Gabbro
15
260
14
16
12
16.8
17.1
3.15
0.6
0.30
20
5.9
V o Tuffaceous Lava
32
100
26
32
20
23.5
29.4
2.33
8.2
0.15
18
12.2
St crushed gravel
14
300
16
17
16
22.8
17.5
2.58
0.9
0.22
23
5.3
L I I Limestone
20
200
16
16
16
21.6
17.3
2.69
0.7
0.38
18
19.8
G r Granite
20
230
20
22
18
23.4
22.1
2.62
0.5
0.30
22
9.6
Bit Basanite
20
200
16
15
16
17.9
17.1
2.82
7.0
0.15
27
14.0
Bit Basalt
12
340
11
9
10
14.5
17.1
2.82
1.9
0.15
20
9.8
I'able 1. Kesuits of the aggregate tests.
X
ACV
Ten % fines
AIV
MAIV
Dutch AIV
Y-13.331n(X)-18.78
Y-2.46X'0.72
German ATV
LAA
Y ACV
Y«exp(3.74-O.0037X) r = 0.97;se = 2.1
Ten % fines
Y = exp(6.64-0.069X)
Y = 1.03X-1.30 r = 0.92;se = 3.1
Mod. AIV
Y = exp(1.7 + 0.06X) r=0.92;se = 5.2
Dulch AIV
Y = X-1.58 r = 0.H3;sc = 5.0
German AIV
Y = 0.74X + 7.44 r = 0.81;se = 4.1
LAA
Y = L30X-3.53 r = 0,87;sc = 5.7
r»0.93;se"2.8 Y=exp{6.43^.06X) r=0.95;sc = 34.6
r = 0.97;se = 20.9 AIV
Y-0.84X+4
r = 0.95;se = 2.7
r = 0.92;se = 4.2 Y = -15.101n(X) + 97.96 r-0.9O;.sc-4.1 Y = -10.831n(X) +79.34 r = 0.85;se = 3.7 Y = 663X"-0.65 r = 0.93;se = 3.6
r=0.86;sc = 4.1
Y=3095X"-0.95
Y=5433XM.18
r=0.92;se = 47.2 Y - 0 3 6 X + 7.76
Y = -14.681n(X) +96.55
Y = 1959X"-0.88
r»0.92;se = 3.1
r»0.97;se"2.1
Y = 0.79X + 7.03 r = 0.95;se = 2.1 Y = exp(2.22 + 0.(mX) r = 0.98;se = 1.4
r = 0.96;se = 2.2
r = 0.93;se = T l
r = 0.97;se = 3.6
r-0.96;se-2.4
Y = 0.89X + 3
Y = 1.68X-6.46
Y = 1.68X-11.61
Y = X-1.80
r = 0.90;sc = 44.4
Y-0.6X + 6.4
r = 0.92;se = 2.8
r-0.81;sc=4.4 Y = exp(6.7(M).07X) r=0.85;se = 59.1 Y-1.15X-6.21 r-0.95;se»=2.6 Y = 1.92X-21.72 r=0.92;sc=5.8 Y-L28X-9.96 r-0.97;se-2.1
r»0.93;se-3.3 Y = 0.44X+13
Y-0.89X+0.68
Y-18.05ln(X>35.11 r=0.90;sc-3.4 Y = 11575XMJ4 r = 0.93;se=45.4 Y = 21.841n(X)^7.74 r»=0.98;se-lJ Y = 1.24X-7.29 r=0.98;se = 3.2 Y-0.76X+L44 r-0.95;sc-3.0
Y = 0.74X + 8.86
Y = 0.56X+9.70
r = 0.97;se = 1.6
r=0.92;6c-2.8
Y = 0.77X + 6.76
Y = 1.20X + 0.90
r=0.98;se = 2J
r=0.94;se = 3.7
Y = 1.50X-10.80 r = 0.92;se=4.6
Table 2. Matrk showing the regression equations with Y = dependent variable and X = independent variable; r=regression coefficient; se = standard deviation of estimate. A C V = aggregate crushing value; 10 % fines = ten per cent fines value; A I V = aggregate impact value (all according to BS-812, 1975). M A I V = modified aggregate impact value (Hosking and Tubey, 1969); Dutch A I V (Dynamische verbrijzehngswaarde: N E N 5185, draft 1988); German A I V (Schlagzertrümmerungswert SZg/jz: TPMin-StB Teil 5.2.1.4, 1982). L A A = L o s Angeles Abrasion test (ASTM C131-81).
50
r
10 r-n r \
20
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20
20
20
20
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10
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1
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10
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4
30
20
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IQ
I I I I I I
10 20 3 0 Aggregote Crushing Value (.ACV) {%)
I I I
I I
a
fto
I I I I
SZ8/1 2=0.74xACV+7.44
SZ8/l2=0.79xA!V+7.03 3D
' I
%
r=0.95
n=11
00
se = 4
r=0.81 30
30
30
> 20
20
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£
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10
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10
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t I
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10 20 30 Aggregate Crushing Volue (ACV) {%)
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to
20
400
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20 1 1
1
1
1
1 1 1
60
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1 111 1 1 1 1 1 1 1 1 1 11 1 11 11 11 ) 1 T
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•
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r=0.98 •
40
40
r=0.92
H200
3 2001
•
300
Px = 3095xWod.AI\r°-" n=11
se = 2
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100
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