1. STONE MASTIC ASPHALT

2. WHAT IS SMA
Stone mastic asphalt (SMA), also called stone-matrix asphalt. It is homogeneous mixture of selected well graded aggregate , filler and bitumen in such proportions as to yield a plastic and voidless mass which Act as a very dense impermeable surfacing.
It was developed in Germany in the 1960s.

3. COMPOSITION OF SMA
COARSE AGGREGATE
FINE AGGREGATE
BINDER
FILLER
FIBRE

4. PROPERTIES OF COARSE AGGREGATE
Hard
Durable
Free from the organic mattrer
Resistance to stripping
Water absorpton should not be greater than 2%

5. GRADING OF COARSE AGGREGATE
Sieve
SMA 12.5 mm
19.0 mm
100
12.5 mm
90 – 99
9.5 mm
50 – 85
4.75 mm
28 – 40
2.36 mm
16 – 28
75 μm
8 – 11

6. PROPERTIES OF FINE MATERIAL
Water absorption of a fine aggregate of any nominal size from any source must not exceed 3.5%.
Soundness:- The weighted percent loss from a fine aggregate must not exceed 12% of the test portion.

7. PROPERTIES OF FILER
The filler shall be limestone powder passing the mm sieve .
Calcium carbonate content shall not be less than 80% by weight.

8. ADVANTAGE OF SMA Resistance to permanent deformation or rutting
Good durability due to high binder content
Good flexibility and resistance to fatigue
Good wear resistance
Good surface texture

9. DISADVANTAGE OF SMA Increased cost
Increased mixing time and time taken to add extra filler, may result in
reduced productivity.
Possible delays in opening to traffic
Initial skid resistance may be low.

10. MIX DESIGN HARDNESS NUMBER
At the time of manufacturing of 60 to 80 at 25˚c
At the time of laying 10 to 20 at 25˚c
BINDER CONTENT:
14 to 17% by weight of total mix.

11. MIX PROPERTIES Design Parameter Design Criteria Air Voids % 4.0
Voids in Mineral Aggregate,
VMA %
17 Minimum
Tensile Strength Ratio %
70 Minimum
Draindown %
0.3 Maximum

12. TENSILE STRENGTH RATIO, TSR
Checks the moisture susceptibility of the asphalt mixture.
where
S1 = average tensile strength of dry subset
S2 = average tensile strength of moisture conditioned subset

13. Tensile Strength Ratio, TSR

14. DRAINDOWN
Mass of asphalt mortar that has drained from total asphalt mass
Where:
Pi = Initial paper plate mass (grams)
Pf = Final paper plate mass (grams)
W = Mixture mass (grams)
D = % Drain-down