Sand Equivalent: Fact or Fiction
J.S Lowe, Winstone Aggregates
Dr D.J Wilson, The University of Auckland
Prof. P.M Black, The University of Auckland
Contents
Overview of common NZ cleanliness tests
Sand Equivalent
Initial Findings from Experimental Programme
Conclusions
Recommendations for further work
Current New Zealand tests to classify the
cleanliness of fine aggregates and sand
Limit the amount of -75um material
Sand Equivalent
Developed 1954 by Hveem
Methylene Blue or Clay Index
Developed 1967 by Jones
Plasticity Index
Developed 1911 by Atterberg
When are the tests applied to classify the
cleanliness of fine aggregates and sand
Typically:
• All NZ Specifications limit the 75um Material
• All commonly adopt Sand Equivalent
• Clay Index less popular not used in concrete industry
• Plasticity Index mainly used in roading applications
No tests adapted specifically for uniqueness of NZ Rock
sources
SE testing to establish the cleanliness >$2m/annum
Local aggregates are often dismissed due to non
compliance with National NZ Specifications
Sand Equivalent (SE)
• Quickest of current tests taking approx 30 mins
• Settling Test
• Not directly measuring clay content, gives a potential
• Simple and relatively cheap
• Accuracy and repeatability concerns
Initial Findings : Sand Equivalent Versus Clay Index
Clay Index NZS 4407
6
5
4
3
2
1
0
20
25
30
35
40
45
50
55
Sand Equivalent NZS 4407
• Single quarry source & multiple products
• Sample size = 90
• Lower CI with increasing SE
• 37% of samples ≥40 (Sand Equivalent)
• 87% of samples ≤3 (Clay Index)
60
65
70
Initial Findings: Sand Equivalent versus Clay Index
6
• Sample size = 197
• 24% of samples ≥40 (Sand Equivalent)
• 74% of samples ≤3 (Clay Index)
Clay Index NZS 4407
• Multiple Quarries and Products
5
4
3
2
1
0
Clay Index NZS4407
20
25
30
35
40
45
50
55
Sand Equivalent NZS 4407
10
8
6
4
2
0
20
30
40
50
Sand Equivalent NZS4407
60
70
60
65
70
Comparison with % passing 75um
• Single quarry source & multiple products
Clay Index NZS 4407
6
• Sample size = 90
• 37% of samples ≥40 (Sand Equivalent)
• 87% of samples ≤3 (Clay Index)
5
4
3
2
1
0
• 63% of samples ≤7 (% Passing 75um)
20
25
30
35
40
45
50
55
Sand Equivalent NZS 4407
Sand Equivalent
70
60
50
40
30
20
0
5
10
% Passing 75um
15
20
60
65
70
Sand Equivalent v Clay Index
80
Number of Tests 400
Number of Companies 3
70
Number of Rock Types 2
Number of Quarries 8
Sand Equivalent
60
50
40
30
20
10
0
1
2
3
4
5
Clay Index
• Multiple Quarries and Products
• Sample size = 400
• 24% of samples ≥40 (Sand Equivalent)
• 74% of samples ≤3 (Clay Index)
6
7
8
9
10
60
50
40
Sand Equivalent
Greywacke Pap7 (Dry & Washed)
Sand Equivalent
100
Number of tests = 61
90
80
70
30
20
10
0
16
0
/2
01
/2
3
/0
03
9/
01
/2
0
/2
0
/2
01
/2
2
/0
2
/0
03
2/
23
16
02
9/
0
/2
0
/2
0
/2
01
/2
1
/0
1
/0
1
/0
02
2/
26
19
12
01
/2
0
/2
0
/2
0
/2
00
/2
2
/1
2
/1
2
/1
01
5/
29
22
15
12
8/
0
/2
0
/2
0
/2
00
/2
1
/1
1
/1
1
/1
12
1/
24
17
10
0
/2
0
/2
00
/2
0
/1
0
/1
11
3/
27
20
10
0
0
10
10
0
0
10
10
10
0
09
09
09
9
9
09
09
09
9
09
09
Date
10
100
16
0
/2
01
/2
3
/0
03
9/
01
/2
0
/2
0
/2
01
/2
2
/0
2
/0
03
2/
23
16
02
9/
0
/2
0
/2
0
/2
01
/2
1
/0
1
/0
1
/0
02
2/
26
19
12
01
/2
0
/2
0
/2
0
/2
00
/2
2
/1
2
/1
2
/1
01
5/
29
22
15
12
8/
0
/2
0
/2
0
/2
00
/2
1
/1
1
/1
1
/1
12
1/
24
17
10
0
/2
0
/2
00
/2
0
/1
0
/1
11
3/
27
20
10
0
0
10
10
0
0
10
10
10
0
09
09
09
9
9
09
09
09
9
09
09
Date
9
Number of tests = 61
90
8
70
7
60
6
50
5
40
4
30
3
20
2
10
1
0
0
Clay Index
80
Sand Equivalent
Greywacke Pap7 (Dry & Washed)
Sand Equivalent
Clay Index
•AQA Technical Committee 1980
•Don Ferguson
Greywacke Pap7 - SE Settlement Curves
Pukekawa Settlement Curve Pap5
400
450
400
350
350
300
Settlement (mm)
250
200
250
150
100
200
50
0
1
150
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Time (mins)
21
Time (mins)
Otaika Settlement Curve (Pap 5)
Flat Top Settlement Curve (Gap25)
450
450
400
400
350
350
300
Height of Column (mm)
300
250
200
250
200
150
150
100
100
50
50
0
1
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
15
16
17
18
19
20
21
Time (mins)
21
Time (mins)
Greywacke TNZ40 - SE Settlement Curves
Greywacke Gap65 - SE Settlement Curves
400
400
350
350
Settlement (mm)
300
300
Settlement (mm)
Height of Column (mm)
Settlement (mm)
300
250
250
200
200
150
1
150
2
3
4
5
6
7
8
9
10
11
12
13
Settlement Time (mins)
1
2
3
4
5
6
7
8
9
10
11
12
13
Settlement Time (mins)
14
15
16
17
18
19
20
21
14
18
19
20
21
Pap7 Settlement Curve
450
400
350
Settlement (mm)
300
250
200
150
100
50
0
1
6
11
16
21
26
31
36
41
Time (mins)
46
51
56
61
66
71
76
81
Greywacke Settlement Curves (washed pap 7)
450
400
350
Height of Column (mm)
300
250
200
150
100
50
0
1
2
3
4
5
6
7
8
9
10
11
12
Time (mins)
13
14
15
16
17
18
19
20
21
A suggested approach?
• Steady State Sand Equivalent
Allow full settlement to occur
•Normalised Clay Index
CIn = CI ( P x Wp )
Wci
Where:
CIn = normalised clay index
CI = clay index (NZS 4407:1991)
P = Percentage passing 75um (from particle size distribution)
Wp = Weight of sample (from particle size distribution)
Wci = Weight of sample (clay index)
Conclusions
Percentage of fines in NZ aggregate products does
not appear excessive
Evidence to suggest that using Sand Equivalent as
primary test method is not maximising the use of
NZ aggregates
Clay Index and Sand Equivalent give differing
levels of conformance for same sample
Specifications can create testing and consistency
issues for aggregate industry
Specifications are reliant on adopted test methods
for aggregates
Further work
•Relate results to specific swelling clays using
XRD data.
•Analysis of the ultrafines.
•Comparison of SEss to CIn.
• Develop SE and CI Prediction Models.