1. AGGREGATE Aggregates may be NATURAL or MANUFACTURED
Natural aggregates: sand, gravel, crushed rock
Manufactured aggregates: blast furnage slag
Aggregates may also be COARSE or FINE or FILLER
Coarse aggregates: > 4.76mm
Fine aggregates: 0.075mm – 4.76mm
Filler: < 0.075mm

2. COARSE AGGREGATE properties
Strength (kekuatan) and toughness (kekerasan)
Particle shape
Porosity
Surface texture
Surface coatings
Specific gravity
Gradation

3. FINE AGGREGATE properties
Hard
Non-plastic (clean & free from organik materials)
Gradation
Salt content

4. Strength and toughness
- to prevent breakdown under traffic and subsequent loss of stability
no truly satisfactory test to measure the effective strength and toughness
Measured by abrasion test using the Los Angeles Machine

5. Particle shape
- to provide aggregate interlock and stability of mixture
Crushed aggregates give a better interlocking than rounded gravels
Rounded gravels produce a more highly stable surface mixture than crushed aggregates. (adhesi antara agregat dan aspal agregat bulat lebih baik daripada batu pecah)
Thin and elongated aggregates are being subject to size segregation in the mixing process and tend to be of low strength.

6. Porosity
- Porosity gives a proper adhesion between aggregate and bitumen
Porosity affects the economic of mixture
High porosities cause more bitumen will be absorbed into the aggregate (desired around 0.5% of bitumen is absorbed into aggregate)
High porosities generally do not affect the quality of mixture. It could be noted that if more bitumen is absorbed into aggregate this will leave a hard residue on the surface of aggregate particle and then lead to raveling and stripping.

7. Surface texture
The rougher the surface texture of aggregate gives the higher the stability and durability
A rough aggregate surface reduces the displacement under pavement loading and then increases the stability of mixture
Is important to adhesion between aggregate and bitumen. This will increase the durability of mixture

8. Surface coatings
Aggregate may be coated by clay, silt, calcium carbonat, iron oxides, gypsum and other subtances in varying thiskness and hardness.
Surface coatings has responsible for aggregate stripping due to disturb the bitumen to seal the aggregate

9. Specific gravity
Specific gravity is importand for mixture calculation such as to determine the void content of the compacted bituminous mixture
3 (Three) types of aggregate specific gravity:
Bulk specific gravity (Graviti spesifik bulk)
SSD (Saturated Surface Dry) specific gravity (Graviti spesifik kering permukaan jenuh)
Apparent specific gravity ( Graviti spesifik semu)
There is also known ‘effective specific gravity’. It is used to estimate the amount of bitumen absorbed by aggregate

10. Specific gravity
Bulk specific gravity : perbandingan antara berat kering agregat dan volume total agregat
SSD specific gravity : perbandingan antara berat agregat kondisi permukaan jenuh dan volume total agregat
Apparent specific gravity: perbandingan antara berat kering agregat dan volume kedap air agregat
Effective specific gravity: perbandingan antara berat kering agregat dan volume kedap aspal agregat

11. Volume of aggregate to calculate Specific gravity
Volume agregat tanpa pori/ solid (Vs)
Volume agregat kedap air/ impermeable (Vi)
Volume agregat rembes air/ permeable (Vp)
Volume total agregat (V)
Volume agregat rembes aspal
(V-Vs-Vi-Vp)

12. Measuring Specific gravity
Diukur
Ws= berat kering partikel agregat
γw= berat volume air
Bk= berat agregat kering
Ba= berat agregat di dalam air
Bj= berat agregat jenuh air (SSD) Vi Vp Vs Ws Bk
Bulk SG = =
(Vs+Vi+Vp)/γw
Bj - Ba Vs Ws Bj
SSD SG = =
(Vs+Vi+Vp)/γw
Bj - Ba

13. Measuring Specific gravity
Diukur
Ws= berat kering partikel agregat
γw= berat volume air
Bk= berat agregat kering
Ba= berat agregat di dalam air
Bj= berat agregat jenuh air (SSD) Vi Vp Vs Ws Bk
Apparent SG = =
(Vs+Vi)/γw
Bk - Ba
Bulk SG + App SG
Estimasi Effective SG = 2

14. Gradation Gradation is size distribution of aggregate particles
Gradation can be assessed by sieve analysis

15. Aggregate specification
Specification for aggregate is some requirements that to be fulfilled by aggregate properties to ensure the performance of bituminous mixture
For examples
Item Requirement
Apparent Specific gravity min 2.50
Absorption max 3.0%
Abrasion loss max 35%
Elongated and flat particles max 25%
Soundness loss max 12%

16. Sieving analysis ¾’ ½’ No saringan Berat tertahan (g) % tertahan
% lolos ¾’
100 ½’
89.2
4.3
95.7
3/8’
159.7
7.7
88.0
No.4
238.5
11.5
76.5
No.8
311.1
15.0
61.5
No.16
300.7
14.5
47.0
No.30
398.2
19.2
27.8
No.50
327.7
15.8
12.0
No.100
149.3
7.2
4.8
No 200
16.6
0.8
4.0
Pan
83.0
Total
2074.0
2 1/2 inch (63 mm)
2 inch (50 mm)
1 1/2 inch (37.5 mm)
1 inch (25 mm)
3/4 inch (19 mm)
1/2 inch (12.5 mm)
3/8 inch (9.5 mm)
No.4 (4.75 mm)
No.8 (2.36 mm)
No.16 (1.18 mm)
No.30 (0.6 mm)
No.50 (0.3 mm)
No.100 (0.015 mm)
No.200 ( mm)

17. Making gradation curve
No saringan
% lolos ¾’
19 mm
100 ½’
12.5 mm
95.7
3/8’
9.5 mm
88.0
No.4
4.75 mm
76.5
No.8
2.36 mm
61.5
No 10
2.00 mm
57.5
No.16
1.18 mm
47.0
No.30
0.6 mm
27.8
No.50
0.3 mm
12.0
No.100
0.015 mm
4.8
No 200 mm
4.0

18. Type of gradation
GAP GRADED
UNIFORMLY GRADED
WELL GRADED

19. Finer or coarser aggregate
Agregat semakin halus (finer)

20. Blending two aggregates (1)
Sieve no
Grad A
Grad B
Specification
Mean spec (target gradasi)
2 in
100
1.5 in 95
90 – 100
¾ in 63 85
65 – 80
72.5
No 4 25 50
30 – 45
37.5
N0.10 15 36
20 – 35
27.5
No 200 3 7
0 – 5
2.5

21. Blending two aggregates – metode grafis (2)
Hasil blending
A: B = 37 : 63
1.5 in
3/4 in
No 4
No 10
No 200
A = 37%