Transcript AGGREGATE - Indonesian Computer University

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
COARSE AGGREGATE
properties
Strength (kekuatan) and toughness (kekerasan)
Particle shape
Porosity
Surface texture
Surface coatings
Specific gravity
Gradation
FINE AGGREGATE
properties
Hard
Non-plastic (clean & free from organik materials)
Gradation
Salt content
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
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.
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.
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
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
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
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
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)
Measuring Specific gravity
Diukur
Vi
Vs
Ws= berat kering partikel agregat
Vp
γw= berat volume air
Bk= berat agregat kering
Ba= berat agregat di dalam air
Bj= berat agregat jenuh air (SSD)
Ws
Bulk SG =
Vs
SSD SG =
Bk
=
(Vs+Vi+Vp)/γw
Bj - Ba
Ws
Bj
=
(Vs+Vi+Vp)/γw
Bj - Ba
Measuring Specific gravity
Diukur
Ws= berat kering partikel agregat
γw= berat volume air
Bk= berat agregat kering
Ba= berat agregat di dalam air
Vi
Vs
Bj= berat agregat jenuh air (SSD)
Vp
Ws
Apparent SG =
Bk
=
(Vs+Vi)/γw
Bk - Ba
Bulk SG + App SG
Estimasi Effective SG =
2
Gradation
Gradation is size distribution of aggregate particles
Gradation can be assessed by sieve analysis
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%
Sieving analysis
2 1/2 inch (63 mm)
No
saringan
Berat tertahan (g)
% tertahan
% lolos
2 inch (50 mm)
¾’
0
0
100
1 1/2 inch (37.5 mm)
½’
89.2
4.3
95.7
1 inch (25 mm)
3/8’
159.7
7.7
88.0
3/4 inch (19 mm)
No.4
238.5
11.5
76.5
1/2 inch (12.5 mm)
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.8 (2.36 mm)
No.100
149.3
7.2
4.8
No.16 (1.18 mm)
No 200
16.6
0.8
4.0
No.30 (0.6 mm)
Pan
83.0
4.0
No.50 (0.3 mm)
Total
2074.0
100
3/8 inch (9.5 mm)
No.4 (4.75 mm)
No.100 (0.015 mm)
No.200 (0.0075 mm)
Making gradation curve
100
No saringan
%
lolos
¾’
19 mm
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
90
100
80
% Lolos
70
60
50
40
30
No.30
0.6 mm
27.8
No.50
0.3 mm
12.0
20
No.100
0.015 mm
4.8
10
No 200
0.0075 mm
4.0
0
0.001
0.01
0.1
1
Sieve size
10
100
Type of gradation
100
90
80
% Lolos
70
60
GAP GRADED
50
40
UNIFORMLY
GRADED
30
WELL GRADED
20
10
0
0.001
0.01
0.1
1
Sieve size
10
100
Finer or coarser aggregate
100
90
80
% Lolos
70
Agregat semakin
halus (finer)
60
50
40
30
20
10
0
0.001
0.01
0.1
1
Sieve size
10
100
Blending two aggregates (1)
Sieve no
Grad A
Grad B
Specification
Mean spec
(target
gradasi)
2 in
100
100
100
100
1.5 in
100
95
90 – 100
95
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
Blending two aggregates – metode grafis (2)
B = 63%
% Agg B
100
100
1.5 in
90
90
80
A: B = 37 : 63
80
3/4 in
70
60
60
50
50
No 4
40
40
No 10
30
30
20
20
10
10
No 200
0
0
10
20
30
40
50
% Agg A
A = 37%
60
70
80
90
0
100
% Lolos Agg B
70
% Lolos Agg A
Hasil blending